In civil engineering works, the partial or complete replacement of natural coarse aggregate (NCA) by recycled concrete aggregate (RCA) is most often associated with inferior mechanical properties including bond to embedded steel bars. The main objective of this paper is to evaluate the efficiency of styrene-butadiene rubber (SBR) polymeric latexes to compensate such losses. Two RCA quality types were tested in different concrete mixtures prepared with 320 or 440 kg/m3 cement; the SBR addition rates varied from 1% to 4% of cement mass. Test results have shown that SBR can remarkably improve RCA concrete compressive and splitting tensile strengths, particularly when curing is realized in air conditions at 23 3 °C and 50% relative humidity. The bond stress vs. slip curves remained fundamentally similar to those observed with NCA concrete. Yet, the initial stiffness was considerably accentuated with SBR additions together with improved responses of ascending curves and increased ultimate bond strengths.
SELF-COMPACTING CONCRETE USING RECYCLED COARSE AGGREGATEPRIYANSHUSINHA14
National Conference on Advances in Civil & Mechanical Engineering 2020 is an initiative by GSIT, Karwar to bring the students, researchers and faculties on a common platform to share their work for the benefit of mankind. It is a professional group contributing its mite for the headway of new domains of knowledge in the fields of civil & Mechanical Engineering. NCACME is the second followed the first one was conducted in 2017 with a huge response leading to the publication of 46 papers in International Journals.
An Experimental Investigation on Strength Behavior of Concrete by Replacing N...ijsrd.com
Concrete is one of the most widely used construction material in the world. Destruction of concrete structure due to natural calamities like earthquake, tsunami or by the bombardment, it has became a major problem in finding place for dumping the concrete debris particularly in urban areas. This paper deals with the study of strength of concrete incorporating Recycled Aggregate concrete. The main objectives of this investigation is to find out up to what percentage the Natural Coarse Aggregate (N.C.A) can be replaced by R.C.A in the concrete mix and to find out the extra quantity of cement to be added for each percentage replacement by R.C.A to achieve its target mean strength A series of test were carried out to determine the compressive strength, split tensile strength, flexural strength with and without recycled aggregates. Natural coarse aggregates in concrete were replaced with 0%, 20%, 40%, 60%, 80% and 100% of crushed concrete coarse aggregate. For the strength characteristics, the result showed a gradual decrease in compressive strength, split tensile strength, flexural and modulus of elasticity as the percentage of recycled aggregate is increased.
Study on Compressive Strength of Pervious Concrete for Utilisation as PavenentIRJET Journal
This document summarizes a study on the compressive strength of pervious concrete for use as pavement. Pervious concrete allows water to flow through it due to interconnected pores. The study investigated replacing cement and natural aggregates in pervious concrete mixes with demolition waste and fly ash. Specimens with different proportions of these materials were tested. The compressive strength of M25 grade pervious concrete was found to range from 4MPa to 20MPa. The study aimed to determine the extent to which demolition waste and fly ash could replace cement and aggregates without compromising strength and other properties.
This document summarizes a study on using recycled concrete aggregate in concrete. It discusses that recycled aggregate can reduce environmental impacts from construction waste and lower costs. The study tested the compressive strength, split tensile strength, and flexural strength of concrete with 20%, 40%, and 60% replacement of natural coarse aggregate with recycled aggregate. The 40% replacement mix achieved the highest strengths. The study concluded that recycled aggregate concrete can meet design requirements and is a sustainable construction material option.
Applications of high performance lightweight concrete in a floating barge gateUTHM
This document discusses the application of high performance lightweight concrete (HPLC) in a floating concrete barge gate with a 100-year service life. HPLC was used due to its high strength, workability, low permeability and high durability properties which are essential for the long service life. The HPLC mix design incorporated lightweight aggregate, a low water-cement ratio of 0.38, and corrosion inhibitors to enhance chloride resistance. Chloride diffusion modeling predicted the concrete would resist chloride penetration for over 100 years. Additional protection at construction joints included PVC waterstops and hydrophilic resin injection to prevent water and chloride ingress.
A Study on Strength Properties of Concrete Made with Waste Ready-Mix Concrete...IRJET Journal
This document presents a study on the strength properties of concrete made with waste ready-mix concrete as coarse aggregate and partial replacement of cement by ground granulated blast furnace slag (GGBS). Various mixes were designed to replace natural coarse aggregate with recycled coarse aggregate at percentages of 20%, 40%, and 60%. Cubes and cylinders were cast and tested to determine the compressive and split tensile strengths of the mixes at 28 days. The results showed that concrete with recycled coarse aggregate and GGBS replacement achieved comparable strength to conventional concrete. Finite element analysis was also conducted to validate the experimental results. The study concludes that waste ready-mix concrete can effectively be used as coarse aggregate in concrete production.
This document summarizes the mix design study for the Badovli RCC Dam in Iran. Laboratory tests were conducted to determine the optimum mix proportions to achieve the target compressive strength of 120 kg/cm2 at 180 days. Aggregates from local borrow areas were tested and found suitable. A mix with 160 kg/m3 of cement, 40%/40%/20% ratio of fine to coarse aggregates, and a w/c ratio of 0.72 achieved a Vebe density of 2470 kg/m3 and compressive strengths exceeding the target. The mix design was found to meet requirements for the RCC dam body.
ENHANCEMENT OF SEISMIC PERFORMANCE OF STRUCTURES USING HyFRCIEI GSC
Presentation on ENHANCEMENT OF SEISMIC PERFORMANCE OF STRUCTURES USING HyFRC by Needhi Kotoky Under the supervision of Dr. Anjan Dutta and Dr. Sajal K. Deb Department of Civil EngineeringIndian Institute of Technology Guwahati
SELF-COMPACTING CONCRETE USING RECYCLED COARSE AGGREGATEPRIYANSHUSINHA14
National Conference on Advances in Civil & Mechanical Engineering 2020 is an initiative by GSIT, Karwar to bring the students, researchers and faculties on a common platform to share their work for the benefit of mankind. It is a professional group contributing its mite for the headway of new domains of knowledge in the fields of civil & Mechanical Engineering. NCACME is the second followed the first one was conducted in 2017 with a huge response leading to the publication of 46 papers in International Journals.
An Experimental Investigation on Strength Behavior of Concrete by Replacing N...ijsrd.com
Concrete is one of the most widely used construction material in the world. Destruction of concrete structure due to natural calamities like earthquake, tsunami or by the bombardment, it has became a major problem in finding place for dumping the concrete debris particularly in urban areas. This paper deals with the study of strength of concrete incorporating Recycled Aggregate concrete. The main objectives of this investigation is to find out up to what percentage the Natural Coarse Aggregate (N.C.A) can be replaced by R.C.A in the concrete mix and to find out the extra quantity of cement to be added for each percentage replacement by R.C.A to achieve its target mean strength A series of test were carried out to determine the compressive strength, split tensile strength, flexural strength with and without recycled aggregates. Natural coarse aggregates in concrete were replaced with 0%, 20%, 40%, 60%, 80% and 100% of crushed concrete coarse aggregate. For the strength characteristics, the result showed a gradual decrease in compressive strength, split tensile strength, flexural and modulus of elasticity as the percentage of recycled aggregate is increased.
Study on Compressive Strength of Pervious Concrete for Utilisation as PavenentIRJET Journal
This document summarizes a study on the compressive strength of pervious concrete for use as pavement. Pervious concrete allows water to flow through it due to interconnected pores. The study investigated replacing cement and natural aggregates in pervious concrete mixes with demolition waste and fly ash. Specimens with different proportions of these materials were tested. The compressive strength of M25 grade pervious concrete was found to range from 4MPa to 20MPa. The study aimed to determine the extent to which demolition waste and fly ash could replace cement and aggregates without compromising strength and other properties.
This document summarizes a study on using recycled concrete aggregate in concrete. It discusses that recycled aggregate can reduce environmental impacts from construction waste and lower costs. The study tested the compressive strength, split tensile strength, and flexural strength of concrete with 20%, 40%, and 60% replacement of natural coarse aggregate with recycled aggregate. The 40% replacement mix achieved the highest strengths. The study concluded that recycled aggregate concrete can meet design requirements and is a sustainable construction material option.
Applications of high performance lightweight concrete in a floating barge gateUTHM
This document discusses the application of high performance lightweight concrete (HPLC) in a floating concrete barge gate with a 100-year service life. HPLC was used due to its high strength, workability, low permeability and high durability properties which are essential for the long service life. The HPLC mix design incorporated lightweight aggregate, a low water-cement ratio of 0.38, and corrosion inhibitors to enhance chloride resistance. Chloride diffusion modeling predicted the concrete would resist chloride penetration for over 100 years. Additional protection at construction joints included PVC waterstops and hydrophilic resin injection to prevent water and chloride ingress.
A Study on Strength Properties of Concrete Made with Waste Ready-Mix Concrete...IRJET Journal
This document presents a study on the strength properties of concrete made with waste ready-mix concrete as coarse aggregate and partial replacement of cement by ground granulated blast furnace slag (GGBS). Various mixes were designed to replace natural coarse aggregate with recycled coarse aggregate at percentages of 20%, 40%, and 60%. Cubes and cylinders were cast and tested to determine the compressive and split tensile strengths of the mixes at 28 days. The results showed that concrete with recycled coarse aggregate and GGBS replacement achieved comparable strength to conventional concrete. Finite element analysis was also conducted to validate the experimental results. The study concludes that waste ready-mix concrete can effectively be used as coarse aggregate in concrete production.
This document summarizes the mix design study for the Badovli RCC Dam in Iran. Laboratory tests were conducted to determine the optimum mix proportions to achieve the target compressive strength of 120 kg/cm2 at 180 days. Aggregates from local borrow areas were tested and found suitable. A mix with 160 kg/m3 of cement, 40%/40%/20% ratio of fine to coarse aggregates, and a w/c ratio of 0.72 achieved a Vebe density of 2470 kg/m3 and compressive strengths exceeding the target. The mix design was found to meet requirements for the RCC dam body.
ENHANCEMENT OF SEISMIC PERFORMANCE OF STRUCTURES USING HyFRCIEI GSC
Presentation on ENHANCEMENT OF SEISMIC PERFORMANCE OF STRUCTURES USING HyFRC by Needhi Kotoky Under the supervision of Dr. Anjan Dutta and Dr. Sajal K. Deb Department of Civil EngineeringIndian Institute of Technology Guwahati
A Feasibility Study on Mechanical Properties of Concrete with Graphene OxideIRJET Journal
This study investigated using graphene oxide (GO) to improve the mechanical properties of concrete. GO was added at concentrations of 1% and 2% by weight of cement to concrete mixes. Specimens of both concrete cubes and cylinders were cast and tested after 28, 56, and 90 days of curing. The concrete containing GO showed improved compressive and split tensile strengths compared to normal concrete without GO. The study demonstrated the feasibility of using GO to enhance the mechanical properties of concrete.
IRJET- Effect of Styrene-Butadiene-Rubber(SBR) Latex on Compressive Stren...IRJET Journal
The document studies the effect of styrene-butadiene rubber (SBR) latex on the compressive strength of high-performance concrete (HPC) made with artificial sand and ordinary Portland cement (OPC). Concrete cubes were prepared with 0%, 1%, 2%, 3%, 4%, and 5% SBR latex by weight of cement and tested at 7, 14, and 28 days. Test results showed that the 3% SBR latex mix achieved the highest compressive strength of 53.9 MPa at 28 days, while the plain HPC reached 42.33 MPa. Similarly, the flexural strength was highest at 3.6 MPa for the 3% SBR latex mix compared to 3.52 MPa for
This document summarizes a study on the durability and strength properties of high performance self-compacting concrete with ground granulated blast furnace slag (GGBS) and silica fumes. Seven concrete mixes were prepared with different replacement levels of GGBS (10-30%) and silica fumes (3-9%). Tests were conducted to evaluate the workability, mechanical strength, and rapid chloride permeability of the hardened concrete at various ages. The results showed that the addition of GGBS and silica fumes improved the density and reduced permeability of the self-compacting concrete, leading to enhanced durability, while maintaining adequate compressive and tensile strengths.
This document discusses concrete mix proportioning and design. It provides information on:
1. The different types of mix proportioning including nominal mix and design mix. Nominal mix uses fixed proportions while design mix determines proportions based on fresh and hardened concrete properties.
2. The procedure for mix design according to IS 10262:2009 including determining target mean strength, selecting water-cement ratio, calculating cement and aggregate contents.
3. An example of designing an M30 concrete mix according to the code. The mix had a water-cement ratio of 0.45, cement content of 413kg/m3, fine aggregate content of 724kg/m3 and coarse aggregate content of 1098kg
IRJET- Experimental Study on Strength Properties of Concrete with Partial...IRJET Journal
1) The study experimentally investigates the strength properties of concrete with partial replacement of cement by Alccofine and replacement of river sand by manufactured sand (m-sand).
2) Compressive and flexural strengths were tested on cubes and beams at 7 and 28 days of curing.
3) The results show that concrete made with 20% replacement of cement by Alccofine exhibited the highest strength increase of 19.68% for compressive strength and 11.07% for flexural strength compared to the control mix.
4) Replacement of river sand by m-sand did not significantly reduce the strength properties of concrete.
The document presents research on the effect of adding silica fume on the strength properties of concrete with partially recycled coarse aggregate. Tests were conducted on M20 and M25 grade concrete with 25% and 50% replacement of natural coarse aggregate with recycled aggregate. Silica fume was added at levels of 5%, 8%, and 12% as a replacement of cement by weight. Compressive strength, split tensile strength, and modulus of rupture were tested at various curing periods. The results showed that compressive strength and split tensile strength initially increased with up to 8% silica fume then decreased with more silica fume. Concrete with 25% recycled aggregate and 8% silica fume achieved the highest strengths
The document compares the concrete mix design methods outlined in the Indian Standards (IS) 10262:2009 and the American Concrete Institute (ACI) 211.1. Some key differences are noted:
- IS 10262:2009 is adapted from the ACI method and requires developing a water-cement ratio curve based on local materials, while older IS and ACI methods used generalized curves.
- The older IS method determined sand content before coarse aggregate content, while ACI and new IS follow the reverse order.
- Calculations of ingredients differ between methods.
- An example mix design for M20 concrete is provided using both new IS and ACI methods to illustrate the procedures.
Durability Characteristics of Fiber Reinforced Geopolymer Concrete Incorporat...IRJET Journal
This document summarizes a study on the durability characteristics of fiber reinforced geopolymer concrete incorporating fly ash and ground granulated blast furnace slag (GGBS). Tests were conducted to determine the sulfate resistance, chloride resistance, water absorption, and abrasion resistance of the concrete. Various fiber dosages were tested. The results showed that the geopolymer concrete exhibited better durability when exposed to sulfate and chloride environments compared to ordinary Portland cement concrete. The geopolymer concrete also had lower water absorption.
Literature Survey on Self-Compacting ConcreteIRJET Journal
This document summarizes literature on self-compacting concrete (SCC). It discusses studies that have partially replaced cement with fly ash, silica fume, and mineral admixtures in SCC mixes. The use of silica fume was found to improve fresh and hardened properties, while fly ash improved fresh properties but reduced hardened properties. Mineral admixtures also positively influenced fresh properties. As the content of rice husk ash increased, workability decreased. Additional studies compared material properties of SCC to normal concrete and found SCC to have higher durability in some areas. Overall, the literature review revealed that further research is needed to establish optimal mix designs for SCC to balance fresh and hardened properties.
EFFECT OF SILICA FUME ON RHEOLOGY AND MECHANICAL PROPERTY OF SELF COMPACTING ...IAEME Publication
This document summarizes a study that evaluated the effect of silica fume on the rheological and mechanical properties of self-compacting concrete. Five concrete mixes were prepared with 0%, 5%, 10%, 15%, and 20% replacement of cement with silica fume. Tests were performed to evaluate the fresh properties like slump flow, V-funnel, L-box, and U-box, as well as the compressive and flexural strengths at 7 and 28 days. The results showed that the 15% silica fume mix met requirements for self-compacting concrete and provided improved rheological and mechanical properties compared to the control mix without silica fume. Replacing 15% of cement with
This document presents a proposed method for designing high-strength concrete mixes containing silica fume. The method aims to determine mix proportions that achieve compressive strengths between 41-90 MPa, with maximum aggregate sizes of 14-25 mm and silica fume replacements of 5-15% by weight of cement. The method involves fixing the cementitious material at 520 kg/m3 and determining initial superplasticizer dosages, water-cement ratios, and aggregate contents needed to achieve the target strengths through a series of trial mixtures. Forty-five initial trials were used to establish superplasticizer dosages, followed by additional trials to refine the relationships between water-cement ratio, aggregate size and amount, and achieved compress
IRJET- Performance of RC Beams Cast using Normal and Self-Compacting Concrete...IRJET Journal
This document presents research on the performance of reinforced concrete (RC) beams made with normal concrete and self-compacting concrete (SCC) with different reinforcement ratios. Trial mixes were developed for normal concrete and SCC to select suitable mixes. Beams were cast using the selected normal and SCC mixes with under, balanced, and over reinforcement ratios. The beams were tested and analyzed according to the Egyptian code of practice (ECP) and American concrete institute (ACI) code to compare deflections. Test results showed differences in cracking and failure loads between experimental, ECP, and ACI analyses of the beams. The research aims to investigate the structural performance of SCC beams compared to normal concrete beams and verify differences between deflection
The document discusses a study on the fatigue performance of rubber-modified recycled aggregate concrete (RRAC) for use in pavements. The study found that adding rubber particles to recycled aggregate concrete (RAC) improved its bending deformation capability and fatigue life. Specifically, RRAC with 20% rubber particles by volume had the highest fatigue strength and ultimate strain, increasing 4.2% and 3.46 times compared to RAC alone. While strength generally decreased as rubber content increased, RRAC continued to have slightly better fatigue strength than RAC even with 30% rubber particles. The use of RRAC provides benefits for recycling demolition waste while reducing weaknesses of RAC.
This document presents research on the compressive strength of bamboo leaf ash (BLA) blended cement concrete cured in different sulphate environments. Concrete cubes with 0%, 5%, 10%, and 15% replacement of cement with BLA were cured in water and sulphate solutions of varying concentrations for 21 and 28 days. Testing found that BLA concrete strengths generally increased with higher sulphate concentrations and longer curing times compared to plain cement concrete. Replacement of 10% cement with BLA produced the highest strengths. The results indicate BLA concrete has improved sulphate resistance and could be suitable for use in sulphate environments where early strength is not critical.
This document discusses a study on the effect of using Sudanese aggregates and supplementary cementitious materials like silica fume and fly ash to produce high strength concrete. Hundreds of concrete specimens with different mixtures of local materials, silica fume, fly ash, and water-cement ratios were tested to determine compressive strength and workability. The results showed that local Sudanese materials can be used to successfully produce concrete with a compressive strength of 80 MPa when combined with supplementary cementitious materials. Water-cement ratio had an inverse relationship with compressive strength. Silica fume improved short and long-term concrete properties while fly ash inversely affected 28-day strength. The study aims to provide insights for producing
IRJET- Study on the Physical Properties of Concrete Prepared with Partial...IRJET Journal
This document summarizes a study on the physical properties of concrete prepared with partial replacement of cement by waste materials such as alccofine, GGBS, and meta-kaoline. The study found that replacing cement with:
1) Alccofine up to 10% increased compressive strength but strength started reducing after 10% replacement.
2) GGBS up to 15% increased compressive strength but strength started reducing after 15% replacement.
3) Meta-kaoline up to 10% increased compressive strength but strength started reducing after 10% replacement.
The study concluded that these waste materials can partially replace cement in concrete up to certain thresholds to increase strength, but replacing beyond
IRJET- Experimental Investigation on Concrete by Partial Replacement of Coars...IRJET Journal
This document presents the results of an experimental study investigating the effects of partially replacing coarse aggregate with cinder in concrete. M30 concrete mixes were designed using the ISI method. Cubes and cylinders were cast with 0%, 20%, 40%, 60%, 80%, and 100% replacement of coarse aggregate with cinder and tested for compressive strength, split tensile strength, and flexural strength at 7 and 28 days. The results showed that compressive strength, split tensile strength, and flexural strength generally decreased as the cinder replacement ratio increased. The highest strengths were obtained with 40-60% cinder replacement. Overall, partially replacing coarse aggregate with cinder produced lightweight concrete with reasonably good strength.
Experimental investigation on effect of mineral admixtures on high performanc...eSAT Journals
Abstract Now a day's high performance concrete is globally used in the infrastructure industry for strong and durable structure, to produced high performance concrete various supplementary cementitious material are used as mineral admixture. This research involves the use of Fly ash, Alccofine and Silica fume at various proportions to enhance the compressive strength of high performance concrete. the investigation was carried out by replacing 10% fly ash along with 17% of alccofine and 10% fly ash along with 17% of silica fume by weight of cementitious material. To cover a wide range of compressive strength of concrete various water binder ratio (W/b) of 0.25, 0.3 and 0.35 were used. The effect of various parameters such as percentage replacement of mineral admixture, water to binder ratio and corresponding compressive strength is studied on fresh and hardened state of concrete. The study mainly consisted of establishing relation between these parameters graphically. Investigation demonstrates that alcofine performs batter than that of silica fume along with fly ash in fresh and harden state of concrete. Keywords: High Performance Concrete, Fly Ash, Alccofine, Silica Fume, workability, Compressive strength
Studies on usage potential of broken tiles as part replacement to coarse aggr...eSAT Journals
Abstract Concrete has several appealing characteristics that have made it as a widely used construction material. It is the material of choice where strength, performance, durability etc., are required and concrete is undoubtedly most versatile construction material. The present study aims at utilization and to ascertain the suitability of tile aggregate as partial replacement to coarse aggregate in normal pervious and blended concretes. The utility of partial replacement of tile waste as aggregates along with partially replacing OPC by fly ash is also addressed in the current work. The strength performance of these concretes (Tiled waste based, tiled waste based pervious, and tile & fly ash based blended concretes) with conventional concretes is studied and important findings are reported. Keywords: Clay tile aggregates, fly ash, replacement material, pervious concrete
Use of construction renovation and demolition waste in partial replacement of...eSAT Journals
Abstract Concrete is a pourable mix of cement, water, sand, and gravel that hardens into a super strong building material. In the recent decades demolition of old buildings, renovation of construction gave rise to gargantuan amounts of construction and demolition waste. Even the waste produced by industries and households got amplified. So experiments were carried out in the laboratory to scrutinize a concrete made of partial replacement of coarse aggregate with construction and demolition waste materials like ceramic tiles waste, plastic debris, crushed bricks. The resultant concrete thus produced was tested on the following parameters like compressive strength, workability, flexural strength. The results thus obtained are compared with a plain cement concrete. By using low weight materials like plastic debris we got a light weight concrete. The workability of concrete produced with construction waste when compared with plain cement concrete is not reliable but it produced a considerable increase in the compressive strength. So we have increased quantity of plastic debris and deducted some quantity of other waste, by this the workability standards are maintained .Hence by using required quantities strength and workability are acquired. Economy plays a imperative role in any construction, by partially replacing of coarse aggregate with construction and demolition waste, plastic waste the cost of construction can be reduced. These wastes can cause pollution that effects human health. Using these wastes effectively in construction activities the rate of pollution can also be controlled. Even the properties of concrete can also be improved. Key Words: Construction and Demolition waste, Plastic Debris, Compressive Strength, Flexural Strength, Workability.
Effect of robo sand on strength characteristic of recycled aggregate concreteeSAT Journals
Abstract
With increased depletion of natural construction materials, alternative means must be sought for substitution of the same. Excessive energy consumption in the production of construction materials, environmental setbacks and debris disposal are some of the other burning issues fuelling the need for reuse of the raw materials. With the need of natural sand, there is an urgent need for a product that matches the properties of natural sand in concrete. Construction- Demolition waste and ROBO Sand are some of the upcoming resources which enables effective replacement of the materials of mineral origin. In the present work, natural coarse aggregate was replaced with recycled coarse aggregate and river sand was replaced with ROBO Sand in different percentages in plain cement concrete. Different strength test were conducted with combination of ROBO Sand and recycled aggregate to study the effect of these two materials on strength Concrete with a characteristic compressive strength of 30 N/mm2 (M30 grade), was used for our study. In total, 16 sets of 6 cubes each were cast and tested.
Keywords: ROBO Sand, recycled aggregate
Final review ppt project EFFECTIVENESS OF USING RECYCLED COARSE AGGREGATES IN...Selva Prakash
1) An experimental study was conducted to determine the effectiveness of using recycled coarse aggregates (RCA) in concrete. Concrete mixes were prepared by replacing normal coarse aggregates with RCA at percentages ranging from 20-40%.
2) Compressive strength tests were performed on concrete cubes at ages of 12 hours, 3 days, 7 days, and 28 days. The results showed that concrete with 40% replacement of RCA achieved higher compressive strengths compared to normal concrete at 28 days.
3) Replacement levels of 20-25% RCA resulted in compressive strengths similar to normal concrete at all ages tested. Higher replacement levels of 30% showed similar early strengths but decreased 28 day strength. The study concluded
A Feasibility Study on Mechanical Properties of Concrete with Graphene OxideIRJET Journal
This study investigated using graphene oxide (GO) to improve the mechanical properties of concrete. GO was added at concentrations of 1% and 2% by weight of cement to concrete mixes. Specimens of both concrete cubes and cylinders were cast and tested after 28, 56, and 90 days of curing. The concrete containing GO showed improved compressive and split tensile strengths compared to normal concrete without GO. The study demonstrated the feasibility of using GO to enhance the mechanical properties of concrete.
IRJET- Effect of Styrene-Butadiene-Rubber(SBR) Latex on Compressive Stren...IRJET Journal
The document studies the effect of styrene-butadiene rubber (SBR) latex on the compressive strength of high-performance concrete (HPC) made with artificial sand and ordinary Portland cement (OPC). Concrete cubes were prepared with 0%, 1%, 2%, 3%, 4%, and 5% SBR latex by weight of cement and tested at 7, 14, and 28 days. Test results showed that the 3% SBR latex mix achieved the highest compressive strength of 53.9 MPa at 28 days, while the plain HPC reached 42.33 MPa. Similarly, the flexural strength was highest at 3.6 MPa for the 3% SBR latex mix compared to 3.52 MPa for
This document summarizes a study on the durability and strength properties of high performance self-compacting concrete with ground granulated blast furnace slag (GGBS) and silica fumes. Seven concrete mixes were prepared with different replacement levels of GGBS (10-30%) and silica fumes (3-9%). Tests were conducted to evaluate the workability, mechanical strength, and rapid chloride permeability of the hardened concrete at various ages. The results showed that the addition of GGBS and silica fumes improved the density and reduced permeability of the self-compacting concrete, leading to enhanced durability, while maintaining adequate compressive and tensile strengths.
This document discusses concrete mix proportioning and design. It provides information on:
1. The different types of mix proportioning including nominal mix and design mix. Nominal mix uses fixed proportions while design mix determines proportions based on fresh and hardened concrete properties.
2. The procedure for mix design according to IS 10262:2009 including determining target mean strength, selecting water-cement ratio, calculating cement and aggregate contents.
3. An example of designing an M30 concrete mix according to the code. The mix had a water-cement ratio of 0.45, cement content of 413kg/m3, fine aggregate content of 724kg/m3 and coarse aggregate content of 1098kg
IRJET- Experimental Study on Strength Properties of Concrete with Partial...IRJET Journal
1) The study experimentally investigates the strength properties of concrete with partial replacement of cement by Alccofine and replacement of river sand by manufactured sand (m-sand).
2) Compressive and flexural strengths were tested on cubes and beams at 7 and 28 days of curing.
3) The results show that concrete made with 20% replacement of cement by Alccofine exhibited the highest strength increase of 19.68% for compressive strength and 11.07% for flexural strength compared to the control mix.
4) Replacement of river sand by m-sand did not significantly reduce the strength properties of concrete.
The document presents research on the effect of adding silica fume on the strength properties of concrete with partially recycled coarse aggregate. Tests were conducted on M20 and M25 grade concrete with 25% and 50% replacement of natural coarse aggregate with recycled aggregate. Silica fume was added at levels of 5%, 8%, and 12% as a replacement of cement by weight. Compressive strength, split tensile strength, and modulus of rupture were tested at various curing periods. The results showed that compressive strength and split tensile strength initially increased with up to 8% silica fume then decreased with more silica fume. Concrete with 25% recycled aggregate and 8% silica fume achieved the highest strengths
The document compares the concrete mix design methods outlined in the Indian Standards (IS) 10262:2009 and the American Concrete Institute (ACI) 211.1. Some key differences are noted:
- IS 10262:2009 is adapted from the ACI method and requires developing a water-cement ratio curve based on local materials, while older IS and ACI methods used generalized curves.
- The older IS method determined sand content before coarse aggregate content, while ACI and new IS follow the reverse order.
- Calculations of ingredients differ between methods.
- An example mix design for M20 concrete is provided using both new IS and ACI methods to illustrate the procedures.
Durability Characteristics of Fiber Reinforced Geopolymer Concrete Incorporat...IRJET Journal
This document summarizes a study on the durability characteristics of fiber reinforced geopolymer concrete incorporating fly ash and ground granulated blast furnace slag (GGBS). Tests were conducted to determine the sulfate resistance, chloride resistance, water absorption, and abrasion resistance of the concrete. Various fiber dosages were tested. The results showed that the geopolymer concrete exhibited better durability when exposed to sulfate and chloride environments compared to ordinary Portland cement concrete. The geopolymer concrete also had lower water absorption.
Literature Survey on Self-Compacting ConcreteIRJET Journal
This document summarizes literature on self-compacting concrete (SCC). It discusses studies that have partially replaced cement with fly ash, silica fume, and mineral admixtures in SCC mixes. The use of silica fume was found to improve fresh and hardened properties, while fly ash improved fresh properties but reduced hardened properties. Mineral admixtures also positively influenced fresh properties. As the content of rice husk ash increased, workability decreased. Additional studies compared material properties of SCC to normal concrete and found SCC to have higher durability in some areas. Overall, the literature review revealed that further research is needed to establish optimal mix designs for SCC to balance fresh and hardened properties.
EFFECT OF SILICA FUME ON RHEOLOGY AND MECHANICAL PROPERTY OF SELF COMPACTING ...IAEME Publication
This document summarizes a study that evaluated the effect of silica fume on the rheological and mechanical properties of self-compacting concrete. Five concrete mixes were prepared with 0%, 5%, 10%, 15%, and 20% replacement of cement with silica fume. Tests were performed to evaluate the fresh properties like slump flow, V-funnel, L-box, and U-box, as well as the compressive and flexural strengths at 7 and 28 days. The results showed that the 15% silica fume mix met requirements for self-compacting concrete and provided improved rheological and mechanical properties compared to the control mix without silica fume. Replacing 15% of cement with
This document presents a proposed method for designing high-strength concrete mixes containing silica fume. The method aims to determine mix proportions that achieve compressive strengths between 41-90 MPa, with maximum aggregate sizes of 14-25 mm and silica fume replacements of 5-15% by weight of cement. The method involves fixing the cementitious material at 520 kg/m3 and determining initial superplasticizer dosages, water-cement ratios, and aggregate contents needed to achieve the target strengths through a series of trial mixtures. Forty-five initial trials were used to establish superplasticizer dosages, followed by additional trials to refine the relationships between water-cement ratio, aggregate size and amount, and achieved compress
IRJET- Performance of RC Beams Cast using Normal and Self-Compacting Concrete...IRJET Journal
This document presents research on the performance of reinforced concrete (RC) beams made with normal concrete and self-compacting concrete (SCC) with different reinforcement ratios. Trial mixes were developed for normal concrete and SCC to select suitable mixes. Beams were cast using the selected normal and SCC mixes with under, balanced, and over reinforcement ratios. The beams were tested and analyzed according to the Egyptian code of practice (ECP) and American concrete institute (ACI) code to compare deflections. Test results showed differences in cracking and failure loads between experimental, ECP, and ACI analyses of the beams. The research aims to investigate the structural performance of SCC beams compared to normal concrete beams and verify differences between deflection
The document discusses a study on the fatigue performance of rubber-modified recycled aggregate concrete (RRAC) for use in pavements. The study found that adding rubber particles to recycled aggregate concrete (RAC) improved its bending deformation capability and fatigue life. Specifically, RRAC with 20% rubber particles by volume had the highest fatigue strength and ultimate strain, increasing 4.2% and 3.46 times compared to RAC alone. While strength generally decreased as rubber content increased, RRAC continued to have slightly better fatigue strength than RAC even with 30% rubber particles. The use of RRAC provides benefits for recycling demolition waste while reducing weaknesses of RAC.
This document presents research on the compressive strength of bamboo leaf ash (BLA) blended cement concrete cured in different sulphate environments. Concrete cubes with 0%, 5%, 10%, and 15% replacement of cement with BLA were cured in water and sulphate solutions of varying concentrations for 21 and 28 days. Testing found that BLA concrete strengths generally increased with higher sulphate concentrations and longer curing times compared to plain cement concrete. Replacement of 10% cement with BLA produced the highest strengths. The results indicate BLA concrete has improved sulphate resistance and could be suitable for use in sulphate environments where early strength is not critical.
This document discusses a study on the effect of using Sudanese aggregates and supplementary cementitious materials like silica fume and fly ash to produce high strength concrete. Hundreds of concrete specimens with different mixtures of local materials, silica fume, fly ash, and water-cement ratios were tested to determine compressive strength and workability. The results showed that local Sudanese materials can be used to successfully produce concrete with a compressive strength of 80 MPa when combined with supplementary cementitious materials. Water-cement ratio had an inverse relationship with compressive strength. Silica fume improved short and long-term concrete properties while fly ash inversely affected 28-day strength. The study aims to provide insights for producing
IRJET- Study on the Physical Properties of Concrete Prepared with Partial...IRJET Journal
This document summarizes a study on the physical properties of concrete prepared with partial replacement of cement by waste materials such as alccofine, GGBS, and meta-kaoline. The study found that replacing cement with:
1) Alccofine up to 10% increased compressive strength but strength started reducing after 10% replacement.
2) GGBS up to 15% increased compressive strength but strength started reducing after 15% replacement.
3) Meta-kaoline up to 10% increased compressive strength but strength started reducing after 10% replacement.
The study concluded that these waste materials can partially replace cement in concrete up to certain thresholds to increase strength, but replacing beyond
IRJET- Experimental Investigation on Concrete by Partial Replacement of Coars...IRJET Journal
This document presents the results of an experimental study investigating the effects of partially replacing coarse aggregate with cinder in concrete. M30 concrete mixes were designed using the ISI method. Cubes and cylinders were cast with 0%, 20%, 40%, 60%, 80%, and 100% replacement of coarse aggregate with cinder and tested for compressive strength, split tensile strength, and flexural strength at 7 and 28 days. The results showed that compressive strength, split tensile strength, and flexural strength generally decreased as the cinder replacement ratio increased. The highest strengths were obtained with 40-60% cinder replacement. Overall, partially replacing coarse aggregate with cinder produced lightweight concrete with reasonably good strength.
Experimental investigation on effect of mineral admixtures on high performanc...eSAT Journals
Abstract Now a day's high performance concrete is globally used in the infrastructure industry for strong and durable structure, to produced high performance concrete various supplementary cementitious material are used as mineral admixture. This research involves the use of Fly ash, Alccofine and Silica fume at various proportions to enhance the compressive strength of high performance concrete. the investigation was carried out by replacing 10% fly ash along with 17% of alccofine and 10% fly ash along with 17% of silica fume by weight of cementitious material. To cover a wide range of compressive strength of concrete various water binder ratio (W/b) of 0.25, 0.3 and 0.35 were used. The effect of various parameters such as percentage replacement of mineral admixture, water to binder ratio and corresponding compressive strength is studied on fresh and hardened state of concrete. The study mainly consisted of establishing relation between these parameters graphically. Investigation demonstrates that alcofine performs batter than that of silica fume along with fly ash in fresh and harden state of concrete. Keywords: High Performance Concrete, Fly Ash, Alccofine, Silica Fume, workability, Compressive strength
Studies on usage potential of broken tiles as part replacement to coarse aggr...eSAT Journals
Abstract Concrete has several appealing characteristics that have made it as a widely used construction material. It is the material of choice where strength, performance, durability etc., are required and concrete is undoubtedly most versatile construction material. The present study aims at utilization and to ascertain the suitability of tile aggregate as partial replacement to coarse aggregate in normal pervious and blended concretes. The utility of partial replacement of tile waste as aggregates along with partially replacing OPC by fly ash is also addressed in the current work. The strength performance of these concretes (Tiled waste based, tiled waste based pervious, and tile & fly ash based blended concretes) with conventional concretes is studied and important findings are reported. Keywords: Clay tile aggregates, fly ash, replacement material, pervious concrete
Use of construction renovation and demolition waste in partial replacement of...eSAT Journals
Abstract Concrete is a pourable mix of cement, water, sand, and gravel that hardens into a super strong building material. In the recent decades demolition of old buildings, renovation of construction gave rise to gargantuan amounts of construction and demolition waste. Even the waste produced by industries and households got amplified. So experiments were carried out in the laboratory to scrutinize a concrete made of partial replacement of coarse aggregate with construction and demolition waste materials like ceramic tiles waste, plastic debris, crushed bricks. The resultant concrete thus produced was tested on the following parameters like compressive strength, workability, flexural strength. The results thus obtained are compared with a plain cement concrete. By using low weight materials like plastic debris we got a light weight concrete. The workability of concrete produced with construction waste when compared with plain cement concrete is not reliable but it produced a considerable increase in the compressive strength. So we have increased quantity of plastic debris and deducted some quantity of other waste, by this the workability standards are maintained .Hence by using required quantities strength and workability are acquired. Economy plays a imperative role in any construction, by partially replacing of coarse aggregate with construction and demolition waste, plastic waste the cost of construction can be reduced. These wastes can cause pollution that effects human health. Using these wastes effectively in construction activities the rate of pollution can also be controlled. Even the properties of concrete can also be improved. Key Words: Construction and Demolition waste, Plastic Debris, Compressive Strength, Flexural Strength, Workability.
Effect of robo sand on strength characteristic of recycled aggregate concreteeSAT Journals
Abstract
With increased depletion of natural construction materials, alternative means must be sought for substitution of the same. Excessive energy consumption in the production of construction materials, environmental setbacks and debris disposal are some of the other burning issues fuelling the need for reuse of the raw materials. With the need of natural sand, there is an urgent need for a product that matches the properties of natural sand in concrete. Construction- Demolition waste and ROBO Sand are some of the upcoming resources which enables effective replacement of the materials of mineral origin. In the present work, natural coarse aggregate was replaced with recycled coarse aggregate and river sand was replaced with ROBO Sand in different percentages in plain cement concrete. Different strength test were conducted with combination of ROBO Sand and recycled aggregate to study the effect of these two materials on strength Concrete with a characteristic compressive strength of 30 N/mm2 (M30 grade), was used for our study. In total, 16 sets of 6 cubes each were cast and tested.
Keywords: ROBO Sand, recycled aggregate
Final review ppt project EFFECTIVENESS OF USING RECYCLED COARSE AGGREGATES IN...Selva Prakash
1) An experimental study was conducted to determine the effectiveness of using recycled coarse aggregates (RCA) in concrete. Concrete mixes were prepared by replacing normal coarse aggregates with RCA at percentages ranging from 20-40%.
2) Compressive strength tests were performed on concrete cubes at ages of 12 hours, 3 days, 7 days, and 28 days. The results showed that concrete with 40% replacement of RCA achieved higher compressive strengths compared to normal concrete at 28 days.
3) Replacement levels of 20-25% RCA resulted in compressive strengths similar to normal concrete at all ages tested. Higher replacement levels of 30% showed similar early strengths but decreased 28 day strength. The study concluded
Presentation on Comparative study Of concrete using Recycled coarse aggregatesShanu Aggarwal
The document provides an overview of a comparative study on concrete using recycled coarse aggregates. It discusses the need for recycled aggregates due to shortage of natural aggregates and increasing construction waste. It also explains the process of recycling concrete. The document then reviews several literature studies on properties of concrete with recycled aggregates. It further lists the various experiments conducted as part of the study, including tests on fine and coarse aggregates, cement, and recycled coarse aggregates. The results of sieve analysis, water absorption, crushing value, impact value, specific gravity tests are presented.
This document is a study on recycled aggregate concrete conducted by Neelanjan Sarkar from Murshidabad College of Engineering & Technology. It discusses what recycled aggregate concrete is, its characteristics, classification, production process, uses, applications, and benefits. Recycled aggregate concrete is produced using crushed waste concrete as a substitute for natural aggregates. It has properties like lower strength, density and higher water absorption compared to normal concrete. However, using recycled materials reduces waste and saves on costs and natural resource usage, making it a more sustainable construction material.
Use of Waste Materials As a replacement of Coarse Aggregate in Concrete MixNitin Yadav
The document discusses the use of waste materials in concrete. It outlines the objectives of reducing waste and finding alternative materials for construction. Three waste materials are examined: e-waste, rubber tire waste, and coconut shell waste. Their properties like water absorption and specific gravity are tested. Previous research on using these wastes in concrete is summarized. Experiments are described to determine properties of materials. A concrete mix design is provided with the goal of achieving 25MPa compressive strength. The document aims to explore sustainable and economical use of waste in construction materials.
This document summarizes research on using demolished concrete waste as coarse aggregate in new concrete production. It finds that as urbanization increases, so does construction waste. Recycling this waste into new concrete aggregates helps preserve natural resources and reduce landfill usage. Tests show concrete with up to 30% recycled aggregates can meet strength standards. International standards and practices for recycled aggregate concrete production are discussed. Barriers to its use in India include a lack of recycling facilities, technology, awareness, and standards. Overall, recycled aggregates produce somewhat weaker concrete but can provide environmental and economic benefits when used appropriately.
This document summarizes a study on using recycled concrete aggregate (RCA) from demolished structures as a replacement for natural coarse aggregate in new concrete. The study found that concrete made with 100% RCA had 87% of the compressive strength of concrete made with only natural aggregates. Using saturated surface dry RCA improved the workability and slump of recycled aggregate concrete compared to dry RCA. Additional cement was needed to achieve strength similar to concrete with natural aggregates only. The aim was to utilize construction waste as a resource in new concrete production.
This study investigated using recycled concrete aggregate (RCA) from demolished structures as coarse aggregate in new concrete. Tests found that concrete with 100% RCA had 87% of the compressive strength of concrete with natural coarse aggregate at 28 days. The slump of RCA concrete was also lower but could be improved by using saturated surface dry RCA. Additional cement was needed for 100% RCA concrete to achieve similar workability and strength as natural aggregate concrete. The results show that while RCA concrete has lower strength and workability, it can still produce adequate quality concrete and promotes more sustainable construction practices through resource reuse.
IRJET- Behaviour of RC Slabs with Recycled Aggregates Subjected to Static and...IRJET Journal
1) The document discusses the use of recycled aggregates from construction and demolition waste in concrete as a replacement for natural aggregates. Recycled aggregates are produced by collecting waste concrete, crushing it, sieving it, and washing it.
2) Previous studies have found that concrete made with recycled aggregates as a partial or full replacement of natural coarse aggregates can achieve comparable compressive, tensile, and flexural strengths as normal concrete. However, further research is still needed to determine the impact on concrete durability.
3) The current study aims to produce recycled aggregates from construction waste on campus and use them in proportions of 0%, 30%, 60%, and 100% as a replacement for natural coarse aggregates in concrete mixes. The
Review on Study of Recycled Aggregate Concrete Containing Silica Fume as Part...IRJET Journal
This document summarizes previous research on recycled aggregate concrete containing silica fume as a partial cement replacement. It discusses studies that investigated how replacing natural aggregates with recycled concrete aggregates at different percentages (0-50%) impacted the mechanical and durability properties of concrete. The results showed that replacing up to 30% of natural aggregates with recycled aggregates can achieve similar strength as conventional concrete, but strength decreases when replacement exceeds 30%. Adding silica fume was found to improve properties such as compressive strength and permeability. The optimal replacement rate of recycled aggregates was determined to be 30%.
IRJET- Mechanical Properties of Fibre Reinforced Concrete using Preserved...IRJET Journal
This document presents research on the mechanical properties of concrete containing preserved quality recycled coarse aggregate and steel fibers. Several mix designs were tested containing different replacement percentages of recycled coarse aggregate (RCA) ranging from 25% to 100% replacement of natural coarse aggregate. Steel fibers were also added at percentages from 0.5% to 2% by volume.
The test results showed that at 25% replacement of natural aggregate with RCA, the compressive strength was comparable to normal concrete. Adding 1.5% steel fibers improved the strength properties. Flexural and split tensile strengths followed a similar trend, with CR25S1.5 (25% RCA, 1.5% fibers) performing best. Using 100% R
IRJET- Experimental Review for Suitability Study of Natural Coarse Aggregates...IRJET Journal
This document presents a study on the suitability of using recycled concrete aggregate (RCA) in structural concrete as a replacement for natural coarse aggregates (NCA). The study found that RCA significantly decreased the workability of concrete mixes compared to NCA. Concretes made with 100% RCA produced 36% lower compressive strength and 11.5% lower splitting tensile strength than a control concrete made with only NCA at 28 days. However, recycled concrete was found to be 24% more cost effective than conventional concrete when RCA is free of cost. Therefore, the study concluded that RCA is suitable for use in low-strength structural applications like pavements and retaining walls where overall project costs can be reduced.
Durability of Recycled Aggregate Concrete with Conventional and Equivalent Mo...IRJET Journal
1) The document reviews the durability of recycled aggregate concrete (RAC) made with conventional mix proportion methods compared to the equivalent mortar volume (EMV) method under different environmental factors like chloride attack, carbonation, freeze-thaw cycles, and water penetration.
2) Test results showed RAC made with the EMV method had improved durability compared to conventional methods, with lower chloride diffusion coefficients, reduced carbonation depths, better resistance to freeze-thaw cycles, and decreased water penetration.
3) The EMV method considers the attached mortar on recycled aggregates and proportions mixes to have the same total mortar volume as conventional concrete, resulting in RAC with properties similar to or better than
A Review on Recycled Aggregates as an Alternative Building MaterialIRJET Journal
This document reviews previous research on using recycled aggregates as an alternative building material in concrete. It summarizes the key findings of several studies that investigated the effects of recycled aggregates on concrete properties such as compressive strength, carbonation behavior, tensile strength, water absorption, and durability. The studies found that concrete made with recycled aggregates can achieve similar strengths as concrete with natural aggregates. However, properties like carbonation and water absorption may be negatively affected by the porosity of recycled aggregates. The document concludes that using recycled aggregates is an effective way to reuse construction waste while producing concrete suitable for building applications.
THE EFFECT OF GLASS FIBER ON FLY ASH BASED GEOPOLYMER CONCRETE USING RECYCLED...IRJET Journal
This document summarizes a study on the effect of adding glass fibers to fly ash-based geopolymer concrete that uses recycled aggregates. The researchers tested geopolymer concretes made with 50%, 80%, and 100% recycled coarse aggregates as partial replacements for natural coarse aggregates. Glass fibers ranging from 0.5-3.5% by weight were added to determine their effect on compressive strength. The results showed that up to 2.5% glass fiber improved compressive strength, but more than 2.5% did not provide further gains. Recycled aggregates reduced compressive, tensile, and flexural strengths compared to natural aggregates, but the lower shrinkage of geopolymer concrete compensated for the higher shrink
IRJET- Self Compacting Concrete with Replacement of Flyash Aggregate as Fine ...IRJET Journal
This document discusses a study on developing self-compacting concrete (SCC) using fly ash as a replacement for fine aggregate and lightweight expanded clay aggregate (LECA) as a replacement for coarse aggregate. SCC is a concrete that can flow and consolidate under its own weight without vibration. The study aims to investigate the fresh and hardened properties of SCC mixtures containing LECA and fly ash. Test methods for assessing properties like flowability, passing ability, and segregation resistance of fresh SCC are described. The advantages of using LECA and fly ash in SCC are also summarized.
Experimental Analysis of Steel Fiber Reinforced Self Compacting ConcreteIRJET Journal
This document summarizes an experimental study on steel fiber reinforced self-compacting concrete (SFRSCC). The study aimed to analyze the mechanical properties of SFRSCC, including compressive and flexural strength, by varying the amount of steel fibers added. The document provides background on self-compacting concrete and steel fibers. It then describes the materials and methodology used, including mix design and test methods. The results showed that compressive strength increased by 25.75% and flexural strength increased by 19.47% for SFRSCC compared to plain self-compacting concrete, for a steel fiber content of 1.75%.
IRJET- Workability and Strength Properties of SCC Made with Processed RCAIRJET Journal
This document summarizes a study on the workability and strength properties of self-consolidating concrete (SCC) made with processed recycled concrete aggregate (RCA). The study investigated how replacing natural coarse aggregates in SCC with 0-50% RCA in 10% intervals impacted properties. Tests were conducted on M30 and M40 grade SCC mixes. The results showed that workability parameters like flowability and passing ability were influenced by the amount of RCA used. Compressive and tensile strengths generally decreased with higher RCA replacement levels. The study aimed to evaluate the suitability of using RCA in SCC.
Structural design and economic evaluation of roller compacted concrete pavementSalih Taner YILDIRIM
Abut, Y., & Yildirim, S. T. (2017, October). Structural design and economic evaluation of roller compacted concrete pavement with recycled aggregates. In IOP Conference Series: Materials Science and Engineering (Vol. 245, No. 2, p. 022064). IOP Publishing.
EXPERIMENTAL INVESTIGATION ON STRENGTH OF CONCRETE BY USING NANO- SILICA AND ...IRJET Journal
- The document experimentally investigates the strength of concrete when cement is partially replaced by nano-silica and fly ash.
- Testing was done on concrete cubes with cement replaced 20-30% by fly ash and 1.5-4.5% by nano-silica. The highest compressive strength was achieved with 20% fly ash and 3% nano-silica replacement.
- Results showed that up to 3% nano-silica replacement, compressive strength initially increased then decreased with further nano-silica for a given fly ash content. Replacing over 30% cement with fly ash decreased strength below the control mix.
IRJET- Recycled Concrete Aggregates: A ReviewIRJET Journal
This document reviews the properties and effects of using recycled concrete aggregates (RCA) in concrete. It finds that:
1) RCA decreases the compressive strength of concrete but yields comparable splitting tensile strength compared to conventional concrete.
2) The modulus of rupture for RCA concrete is slightly less than conventional concrete likely due to the weakened interfacial transition zone from residual mortar on the RCA.
3) The modulus of elasticity is also lower than expected for RCA concrete, caused by the more ductile RCA.
IRJET - Study on High Strength Concrete by using Replacement of Metakaolin an...IRJET Journal
This study investigates the use of metakaolin and copper slag as replacements for cement and fine aggregate respectively in concrete to improve strength and durability. Various literature studies showed that replacing cement with 7.5-15% metakaolin and replacing fine aggregate with 25-50% copper slag increased compressive strength by up to 40% compared to conventional concrete. The objectives of this study are to determine the optimal percentages of metakaolin and copper slag replacements. Concrete mixes with 0-12.5% metakaolin and 0-50% copper slag will be tested to evaluate compressive strength, split tensile strength and workability. The results will provide information on utilizing industrial byproducts in concrete production to enhance sustainability.
To Study the Behaviour of use Bituminous Pavement Wastes in Cement Concreteijtsrd
Generally, aggregate prepare 60 to 75 of total concrete amount, therefore the aggregate choice is crucial, and additionally they regulate concrete qualities. Aggregate offer wear resistance as well as strength. So, the aggregate selection, as well as proportioning, must need more attention. The aggregate is usually crushed rocks for example limestone, coarse gravel, maybe granite as well as good aggregate like sand or maybe stone dust. Aggregate formed Bulk pavement structure. This research paper represents a review on the utilization of bituminous pavement wastes. This can assist in obtaining economic climate in construction of road along with preserving environment friendly degradation in term of decreased amount of pollution as well as mining. Gulshan | Nitin Thakur "To Study the Behaviour of use Bituminous Pavement Wastes in Cement Concrete" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd28042.pdfPaper URL: https://www.ijtsrd.com/engineering/civil-engineering/28042/to-study-the-behaviour-of-use-bituminous-pavement-wastes-in-cement-concrete/gulshan
IRJET- Analysis of FRP in Strengthened RC ColumnsIRJET Journal
The document discusses a research study that analyzed the use of glass fiber reinforced polymer (GFRP) wraps to rehabilitate reinforced concrete columns damaged by corrosion. Concrete columns with two different levels of corrosion damage were wrapped with various GFRP materials and thicknesses and tested to evaluate how the GFRP affected the strength, deformation, ductility, and failure modes. The research aims to assess the effectiveness of GFRP wrapping as a rehabilitation technique for corrosion-damaged concrete columns and develop models to predict the performance of GFRP-confined corroded columns.
This document evaluates the strength parameters of self-compacting concrete incorporated with carbon and glass fibres. It discusses how the concrete was made with various percentages of micro silica and fibres as a replacement for cement. The compressive, tensile, and flexural strength of the concrete mixtures were tested at 7 and 28 days. The results showed that the concrete achieved the highest strength at 0.6% addition of carbon or glass fibres, with carbon fibres performing slightly better. In conclusion, the compressive strength increased by 12% for carbon fibre and 8% for glass fibre mixtures at the 0.6% fibre level.
This document summarizes a study on the effect of using recycled coarse aggregate (RCA) and fly ash (FA) in concrete. Cubes were cast by replacing natural coarse aggregate with 10-40% RCA and cement with 10-30% FA. Testing showed that:
1. Workability decreased as RCA content increased but increased with FA due to its lubricating effect.
2. Bulk density decreased slightly with higher RCA content due to old mortar, and more with higher FA content as it has lower density than cement.
3. Compressive strength was maintained up to 30% RCA and 20% FA replacement, with 20% FA replacement showing optimum strength.
Similar to USE OF SBR LATEXES TO MITIGATE INFERIOR CONCRETE PROPERTIES RESULTING FROM RECYCLED COARSE AGGREGATES (20)
Submission Deadline: 30th September 2022
Acceptance Notification: Within Three Days’ time period
Online Publication: Within 24 Hrs. time Period
Expected Date of Dispatch of Printed Journal: 5th October 2022
MODELING AND ANALYSIS OF SURFACE ROUGHNESS AND WHITE LATER THICKNESS IN WIRE-...IAEME Publication
White layer thickness (WLT) formed and surface roughness in wire electric discharge turning (WEDT) of tungsten carbide composite has been made to model through response surface methodology (RSM). A Taguchi’s standard Design of experiments involving five input variables with three levels has been employed to establish a mathematical model between input parameters and responses. Percentage of cobalt content, spindle speed, Pulse on-time, wire feed and pulse off-time were changed during the experimental tests based on the Taguchi’s orthogonal array L27 (3^13). Analysis of variance (ANOVA) revealed that the mathematical models obtained can adequately describe performance within the parameters of the factors considered. There was a good agreement between the experimental and predicted values in this study.
A STUDY ON THE REASONS FOR TRANSGENDER TO BECOME ENTREPRENEURSIAEME Publication
The study explores the reasons for a transgender to become entrepreneurs. In this study transgender entrepreneur was taken as independent variable and reasons to become as dependent variable. Data were collected through a structured questionnaire containing a five point Likert Scale. The study examined the data of 30 transgender entrepreneurs in Salem Municipal Corporation of Tamil Nadu State, India. Simple Random sampling technique was used. Garrett Ranking Technique (Percentile Position, Mean Scores) was used as the analysis for the present study to identify the top 13 stimulus factors for establishment of trans entrepreneurial venture. Economic advancement of a nation is governed upon the upshot of a resolute entrepreneurial doings. The conception of entrepreneurship has stretched and materialized to the socially deflated uncharted sections of transgender community. Presently transgenders have smashed their stereotypes and are making recent headlines of achievements in various fields of our Indian society. The trans-community is gradually being observed in a new light and has been trying to achieve prospective growth in entrepreneurship. The findings of the research revealed that the optimistic changes are taking place to change affirmative societal outlook of the transgender for entrepreneurial ventureship. It also laid emphasis on other transgenders to renovate their traditional living. The paper also highlights that legislators, supervisory body should endorse an impartial canons and reforms in Tamil Nadu Transgender Welfare Board Association.
BROAD UNEXPOSED SKILLS OF TRANSGENDER ENTREPRENEURSIAEME Publication
Since ages gender difference is always a debatable theme whether caused by nature, evolution or environment. The birth of a transgender is dreadful not only for the child but also for their parents. The pain of living in the wrong physique and treated as second class victimized citizen is outrageous and fully harboured with vicious baseless negative scruples. For so long, social exclusion had perpetuated inequality and deprivation experiencing ingrained malign stigma and besieged victims of crime or violence across their life spans. They are pushed into the murky way of life with a source of eternal disgust, bereft sexual potency and perennial fear. Although they are highly visible but very little is known about them. The common public needs to comprehend the ravaged arrogance on these insensitive souls and assist in integrating them into the mainstream by offering equal opportunity, treat with humanity and respect their dignity. Entrepreneurship in the current age is endorsing the gender fairness movement. Unstable careers and economic inadequacy had inclined one of the gender variant people called Transgender to become entrepreneurs. These tiny budding entrepreneurs resulted in economic transition by means of employment, free from the clutches of stereotype jobs, raised standard of living and handful of financial empowerment. Besides all these inhibitions, they were able to witness a platform for skill set development that ignited them to enter into entrepreneurial domain. This paper epitomizes skill sets involved in trans-entrepreneurs of Thoothukudi Municipal Corporation of Tamil Nadu State and is a groundbreaking determination to sightsee various skills incorporated and the impact on entrepreneurship.
DETERMINANTS AFFECTING THE USER'S INTENTION TO USE MOBILE BANKING APPLICATIONSIAEME Publication
The banking and financial services industries are experiencing increased technology penetration. Among them, the banking industry has made technological advancements to better serve the general populace. The economy focused on transforming the banking sector's system into a cashless, paperless, and faceless one. The researcher wants to evaluate the user's intention for utilising a mobile banking application. The study also examines the variables affecting the user's behaviour intention when selecting specific applications for financial transactions. The researcher employed a well-structured questionnaire and a descriptive study methodology to gather the respondents' primary data utilising the snowball sampling technique. The study includes variables like performance expectations, effort expectations, social impact, enabling circumstances, and perceived risk. Each of the aforementioned variables has a major impact on how users utilise mobile banking applications. The outcome will assist the service provider in comprehending the user's history with mobile banking applications.
ANALYSE THE USER PREDILECTION ON GPAY AND PHONEPE FOR DIGITAL TRANSACTIONSIAEME Publication
Technology upgradation in banking sector took the economy to view that payment mode towards online transactions using mobile applications. This system enabled connectivity between banks, Merchant and user in a convenient mode. there are various applications used for online transactions such as Google pay, Paytm, freecharge, mobikiwi, oxygen, phonepe and so on and it also includes mobile banking applications. The study aimed at evaluating the predilection of the user in adopting digital transaction. The study is descriptive in nature. The researcher used random sample techniques to collect the data. The findings reveal that mobile applications differ with the quality of service rendered by Gpay and Phonepe. The researcher suggest the Phonepe application should focus on implementing the application should be user friendly interface and Gpay on motivating the users to feel the importance of request for money and modes of payments in the application.
VOICE BASED ATM FOR VISUALLY IMPAIRED USING ARDUINOIAEME Publication
The prototype of a voice-based ATM for visually impaired using Arduino is to help people who are blind. This uses RFID cards which contain users fingerprint encrypted on it and interacts with the users through voice commands. ATM operates when sensor detects the presence of one person in the cabin. After scanning the RFID card, it will ask to select the mode like –normal or blind. User can select the respective mode through voice input, if blind mode is selected the balance check or cash withdraw can be done through voice input. Normal mode procedure is same as the existing ATM.
IMPACT OF EMOTIONAL INTELLIGENCE ON HUMAN RESOURCE MANAGEMENT PRACTICES AMONG...IAEME Publication
There is increasing acceptability of emotional intelligence as a major factor in personality assessment and effective human resource management. Emotional intelligence as the ability to build capacity, empathize, co-operate, motivate and develop others cannot be divorced from both effective performance and human resource management systems. The human person is crucial in defining organizational leadership and fortunes in terms of challenges and opportunities and walking across both multinational and bilateral relationships. The growing complexity of the business world requires a great deal of self-confidence, integrity, communication, conflict and diversity management to keep the global enterprise within the paths of productivity and sustainability. Using the exploratory research design and 255 participants the result of this original study indicates strong positive correlation between emotional intelligence and effective human resource management. The paper offers suggestions on further studies between emotional intelligence and human capital development and recommends for conflict management as an integral part of effective human resource management.
VISUALISING AGING PARENTS & THEIR CLOSE CARERS LIFE JOURNEY IN AGING ECONOMYIAEME Publication
Our life journey, in general, is closely defined by the way we understand the meaning of why we coexist and deal with its challenges. As we develop the "inspiration economy", we could say that nearly all of the challenges we have faced are opportunities that help us to discover the rest of our journey. In this note paper, we explore how being faced with the opportunity of being a close carer for an aging parent with dementia brought intangible discoveries that changed our insight of the meaning of the rest of our life journey.
A STUDY ON THE IMPACT OF ORGANIZATIONAL CULTURE ON THE EFFECTIVENESS OF PERFO...IAEME Publication
The main objective of this study is to analyze the impact of aspects of Organizational Culture on the Effectiveness of the Performance Management System (PMS) in the Health Care Organization at Thanjavur. Organizational Culture and PMS play a crucial role in present-day organizations in achieving their objectives. PMS needs employees’ cooperation to achieve its intended objectives. Employees' cooperation depends upon the organization’s culture. The present study uses exploratory research to examine the relationship between the Organization's culture and the Effectiveness of the Performance Management System. The study uses a Structured Questionnaire to collect the primary data. For this study, Thirty-six non-clinical employees were selected from twelve randomly selected Health Care organizations at Thanjavur. Thirty-two fully completed questionnaires were received.
Living in 21st century in itself reminds all of us the necessity of police and its administration. As more and more we are entering into the modern society and culture, the more we require the services of the so called ‘Khaki Worthy’ men i.e., the police personnel. Whether we talk of Indian police or the other nation’s police, they all have the same recognition as they have in India. But as already mentioned, their services and requirements are different after the like 26th November, 2008 incidents, where they without saving their own lives has sacrificed themselves without any hitch and without caring about their respective family members and wards. In other words, they are like our heroes and mentors who can guide us from the darkness of fear, militancy, corruption and other dark sides of life and so on. Now the question arises, if Gandhi would have been alive today, what would have been his reaction/opinion to the police and its functioning? Would he have some thing different in his mind now what he had been in his mind before the partition or would he be going to start some Satyagraha in the form of some improvement in the functioning of the police administration? Really these questions or rather night mares can come to any one’s mind, when there is too much confusion is prevailing in our minds, when there is too much corruption in the society and when the polices working is also in the questioning because of one or the other case throughout the India. It is matter of great concern that we have to thing over our administration and our practical approach because the police personals are also like us, they are part and parcel of our society and among one of us, so why we all are pin pointing towards them.
A STUDY ON TALENT MANAGEMENT AND ITS IMPACT ON EMPLOYEE RETENTION IN SELECTED...IAEME Publication
The goal of this study was to see how talent management affected employee retention in the selected IT organizations in Chennai. The fundamental issue was the difficulty to attract, hire, and retain talented personnel who perform well and the gap between supply and demand of talent acquisition and retaining them within the firms. The study's main goals were to determine the impact of talent management on employee retention in IT companies in Chennai, investigate talent management strategies that IT companies could use to improve talent acquisition, performance management, career planning and formulate retention strategies that the IT firms could use. The respondents were given a structured close-ended questionnaire with the 5 Point Likert Scale as part of the study's quantitative research design. The target population consisted of 289 IT professionals. The questionnaires were distributed and collected by the researcher directly. The Statistical Package for Social Sciences (SPSS) was used to collect and analyse the questionnaire responses. Hypotheses that were formulated for the various areas of the study were tested using a variety of statistical tests. The key findings of the study suggested that talent management had an impact on employee retention. The studies also found that there is a clear link between the implementation of talent management and retention measures. Management should provide enough training and development for employees, clarify job responsibilities, provide adequate remuneration packages, and recognise employees for exceptional performance.
ATTRITION IN THE IT INDUSTRY DURING COVID-19 PANDEMIC: LINKING EMOTIONAL INTE...IAEME Publication
Globally, Millions of dollars were spent by the organizations for employing skilled Information Technology (IT) professionals. It is costly to replace unskilled employees with IT professionals possessing technical skills and competencies that aid in interconnecting the business processes. The organization’s employment tactics were forced to alter by globalization along with technological innovations as they consistently diminish to remain lean, outsource to concentrate on core competencies along with restructuring/reallocate personnel to gather efficiency. As other jobs, organizations or professions have become reasonably more appropriate in a shifting employment landscape, the above alterations trigger both involuntary as well as voluntary turnover. The employee view on jobs is also afflicted by the COVID-19 pandemic along with the employee-driven labour market. So, having effective strategies is necessary to tackle the withdrawal rate of employees. By associating Emotional Intelligence (EI) along with Talent Management (TM) in the IT industry, the rise in attrition rate was analyzed in this study. Only 303 respondents were collected out of 350 participants to whom questionnaires were distributed. From the employees of IT organizations located in Bangalore (India), the data were congregated. A simple random sampling methodology was employed to congregate data as of the respondents. Generating the hypothesis along with testing is eventuated. The effect of EI and TM along with regression analysis between TM and EI was analyzed. The outcomes indicated that employee and Organizational Performance (OP) were elevated by effective EI along with TM.
INFLUENCE OF TALENT MANAGEMENT PRACTICES ON ORGANIZATIONAL PERFORMANCE A STUD...IAEME Publication
By implementing talent management strategy, organizations would have the option to retain their skilled professionals while additionally working on their overall performance. It is the course of appropriately utilizing the ideal individuals, setting them up for future top positions, exploring and dealing with their performance, and holding them back from leaving the organization. It is employee performance that determines the success of every organization. The firm quickly obtains an upper hand over its rivals in the event that its employees having particular skills that cannot be duplicated by the competitors. Thus, firms are centred on creating successful talent management practices and processes to deal with the unique human resources. Firms are additionally endeavouring to keep their top/key staff since on the off chance that they leave; the whole store of information leaves the firm's hands. The study's objective was to determine the impact of talent management on organizational performance among the selected IT organizations in Chennai. The study recommends that talent management limitedly affects performance. On the off chance that this talent is appropriately management and implemented properly, organizations might benefit as much as possible from their maintained assets to support development and productivity, both monetarily and non-monetarily.
A STUDY OF VARIOUS TYPES OF LOANS OF SELECTED PUBLIC AND PRIVATE SECTOR BANKS...IAEME Publication
Banking regulations act of India, 1949 defines banking as “acceptance of deposits for the purpose of lending or investment from the public, repayment on demand or otherwise and withdrawable through cheques, drafts order or otherwise”, the major participants of the Indian financial system are commercial banks, the financial institution encompassing term lending institutions. Investments institutions, specialized financial institution and the state level development banks, non banking financial companies (NBFC) and other market intermediaries such has the stock brokers and money lenders are among the oldest of the certain variants of NBFC and the oldest market participants. The asset quality of banks is one of the most important indicators of their financial health. The Indian banking sector has been facing severe problems of increasing Non- Performing Assets (NPAs). The NPAs growth directly and indirectly affects the quality of assets and profitability of banks. It also shows the efficiency of banks credit risk management and the recovery effectiveness. NPA do not generate any income, whereas, the bank is required to make provisions for such as assets that why is a double edge weapon. This paper outlines the concept of quality of bank loans of different types like Housing, Agriculture and MSME loans in state Haryana of selected public and private sector banks. This study is highlighting problems associated with the role of commercial bank in financing Small and Medium Scale Enterprises (SME). The overall objective of the research was to assess the effect of the financing provisions existing for the setting up and operations of MSMEs in the country and to generate recommendations for more robust financing mechanisms for successful operation of the MSMEs, in turn understanding the impact of MSME loans on financial institutions due to NPA. There are many research conducted on the topic of Non- Performing Assets (NPA) Management, concerning particular bank, comparative study of public and private banks etc. In this paper the researcher is considering the aggregate data of selected public sector and private sector banks and attempts to compare the NPA of Housing, Agriculture and MSME loans in state Haryana of public and private sector banks. The tools used in the study are average and Anova test and variance. The findings reveal that NPA is common problem for both public and private sector banks and is associated with all types of loans either that is housing loans, agriculture loans and loans to SMES. NPAs of both public and private sector banks show the increasing trend. In 2010-11 GNPA of public and private sector were at same level it was 2% but after 2010-11 it increased in many fold and at present there is GNPA in some more than 15%. It shows the dark area of Indian banking sector.
EXPERIMENTAL STUDY OF MECHANICAL AND TRIBOLOGICAL RELATION OF NYLON/BaSO4 POL...IAEME Publication
An experiment conducted in this study found that BaSO4 changed Nylon 6's mechanical properties. By changing the weight ratios, BaSO4 was used to make Nylon 6. This Researcher looked into how hard Nylon-6/BaSO4 composites are and how well they wear. Experiments were done based on Taguchi design L9. Nylon-6/BaSO4 composites can be tested for their hardness number using a Rockwell hardness testing apparatus. On Nylon/BaSO4, the wear behavior was measured by a wear monitor, pinon-disc friction by varying reinforcement, sliding speed, and sliding distance, and the microstructure of the crack surfaces was observed by SEM. This study provides significant contributions to ultimate strength by increasing BaSO4 content up to 16% in the composites, and sliding speed contributes 72.45% to the wear rate
ROLE OF SOCIAL ENTREPRENEURSHIP IN RURAL DEVELOPMENT OF INDIA - PROBLEMS AND ...IAEME Publication
The majority of the population in India lives in villages. The village is the back bone of the country. Village or rural industries play an important role in the national economy, particularly in the rural development. Developing the rural economy is one of the key indicators towards a country’s success. Whether it be the need to look after the welfare of the farmers or invest in rural infrastructure, Governments have to ensure that rural development isn’t compromised. The economic development of our country largely depends on the progress of rural areas and the standard of living of rural masses. Village or rural industries play an important role in the national economy, particularly in the rural development. Rural entrepreneurship is based on stimulating local entrepreneurial talent and the subsequent growth of indigenous enterprises. It recognizes opportunity in the rural areas and accelerates a unique blend of resources either inside or outside of agriculture. Rural entrepreneurship brings an economic value to the rural sector by creating new methods of production, new markets, new products and generate employment opportunities thereby ensuring continuous rural development. Social Entrepreneurship has the direct and primary objective of serving the society along with the earning profits. So, social entrepreneurship is different from the economic entrepreneurship as its basic objective is not to earn profits but for providing innovative solutions to meet the society needs which are not taken care by majority of the entrepreneurs as they are in the business for profit making as a sole objective. So, the Social Entrepreneurs have the huge growth potential particularly in the developing countries like India where we have huge societal disparities in terms of the financial positions of the population. Still 22 percent of the Indian population is below the poverty line and also there is disparity among the rural & urban population in terms of families living under BPL. 25.7 percent of the rural population & 13.7 percent of the urban population is under BPL which clearly shows the disparity of the poor people in the rural and urban areas. The need to develop social entrepreneurship in agriculture is dictated by a large number of social problems. Such problems include low living standards, unemployment, and social tension. The reasons that led to the emergence of the practice of social entrepreneurship are the above factors. The research problem lays upon disclosing the importance of role of social entrepreneurship in rural development of India. The paper the tendencies of social entrepreneurship in India, to present successful examples of such business for providing recommendations how to improve situation in rural areas in terms of social entrepreneurship development. Indian government has made some steps towards development of social enterprises, social entrepreneurship, and social in- novation, but a lot remains to be improved.
OPTIMAL RECONFIGURATION OF POWER DISTRIBUTION RADIAL NETWORK USING HYBRID MET...IAEME Publication
Distribution system is a critical link between the electric power distributor and the consumers. Most of the distribution networks commonly used by the electric utility is the radial distribution network. However in this type of network, it has technical issues such as enormous power losses which affect the quality of the supply. Nowadays, the introduction of Distributed Generation (DG) units in the system help improve and support the voltage profile of the network as well as the performance of the system components through power loss mitigation. In this study network reconfiguration was done using two meta-heuristic algorithms Particle Swarm Optimization and Gravitational Search Algorithm (PSO-GSA) to enhance power quality and voltage profile in the system when simultaneously applied with the DG units. Backward/Forward Sweep Method was used in the load flow analysis and simulated using the MATLAB program. Five cases were considered in the Reconfiguration based on the contribution of DG units. The proposed method was tested using IEEE 33 bus system. Based on the results, there was a voltage profile improvement in the system from 0.9038 p.u. to 0.9594 p.u.. The integration of DG in the network also reduced power losses from 210.98 kW to 69.3963 kW. Simulated results are drawn to show the performance of each case.
APPLICATION OF FRUGAL APPROACH FOR PRODUCTIVITY IMPROVEMENT - A CASE STUDY OF...IAEME Publication
Manufacturing industries have witnessed an outburst in productivity. For productivity improvement manufacturing industries are taking various initiatives by using lean tools and techniques. However, in different manufacturing industries, frugal approach is applied in product design and services as a tool for improvement. Frugal approach contributed to prove less is more and seems indirectly contributing to improve productivity. Hence, there is need to understand status of frugal approach application in manufacturing industries. All manufacturing industries are trying hard and putting continuous efforts for competitive existence. For productivity improvements, manufacturing industries are coming up with different effective and efficient solutions in manufacturing processes and operations. To overcome current challenges, manufacturing industries have started using frugal approach in product design and services. For this study, methodology adopted with both primary and secondary sources of data. For primary source interview and observation technique is used and for secondary source review has done based on available literatures in website, printed magazines, manual etc. An attempt has made for understanding application of frugal approach with the study of manufacturing industry project. Manufacturing industry selected for this project study is Mahindra and Mahindra Ltd. This paper will help researcher to find the connections between the two concepts productivity improvement and frugal approach. This paper will help to understand significance of frugal approach for productivity improvement in manufacturing industry. This will also help to understand current scenario of frugal approach in manufacturing industry. In manufacturing industries various process are involved to deliver the final product. In the process of converting input in to output through manufacturing process productivity plays very critical role. Hence this study will help to evolve status of frugal approach in productivity improvement programme. The notion of frugal can be viewed as an approach towards productivity improvement in manufacturing industries.
A MULTIPLE – CHANNEL QUEUING MODELS ON FUZZY ENVIRONMENTIAEME Publication
In this paper, we investigated a queuing model of fuzzy environment-based a multiple channel queuing model (M/M/C) ( /FCFS) and study its performance under realistic conditions. It applies a nonagonal fuzzy number to analyse the relevant performance of a multiple channel queuing model (M/M/C) ( /FCFS). Based on the sub interval average ranking method for nonagonal fuzzy number, we convert fuzzy number to crisp one. Numerical results reveal that the efficiency of this method. Intuitively, the fuzzy environment adapts well to a multiple channel queuing models (M/M/C) ( /FCFS) are very well.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
2. Yehia Daou and Joseph J. Assaad
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1. INTRODUCTION
The partial or complete replacement of natural coarse aggregate (NCA) by recycled
concrete aggregate (RCA) in concrete production has considerably increased over the
last years. The use of RCA has the potential of diverting construction and demolition
debris from landfills while promoting a sustainable building approach.
Generally, the RCA concrete properties are inferior from equivalent NCA
mixtures, given the poorer quality of recycled aggregates including greater water
absorption and lower density [1,2]. In fact, RCAs are composed of NCA with
approximately 30% of adhered mortar that gives the RCA a rough surface with
numerous pores and micro-cracks. In the fresh state, it has been shown that concrete
workability containing RCA is lower than equivalent NCA mixture, given the more
angular shape and roughened surface texture of recycled aggregates [1,3]. Hence, to
produce similar workability, approximately 5% more water is required for RCA
concrete, while 15% more water is needed when both fine and coarse recycled
aggregates are used. On the hardened state, the use of RCA affects the interfacial
transition zone (ITZ) between aggregates and cement paste, which in its turn, reduces
the strength development. Reductions varying from 5% to 25% are reported for
compressive strength, while the splitting tensile strength remained the same or, at
most, 10% lower [1,4,5,6]. For the bond behavior with embedded steel, the majority
of findings have shown that the stages of load vs. slip curves are similar to NCA
mixtures; yet, the ultimate bond strengths were lower, depending on the concentration
and quality of RCA. For example, Kim et al. [7] reported that bond strength of RCA
concrete decreases gradually when RCA replacement rates increased from 0% to
30%, 60%, and 100%; the highest drop was about 18% from equivalent NCA
concrete. Butler et al. [8] found that ultimate bond strength is directly affected by
RCA quality; on average, RCA concrete developed around 10% to 21% lower bond
strength than equivalent NCA mixture.
Polymeric latexes are widely used in cementitious materials to increase adhesion
and bond strengths to various substrates. Latexes typically include polyvinyl acrylic
(PVA) homo- and copolymer and styrene-butadiene rubber (SBR); these consist of
very small polymer particles (0.05–5 μm) formed by emulsion polymerization and
stabilized in water with the aid of surfactants [9]. Generally, adhesion increases with
the increase in polymer-to-cement ratio (p/c); for example, Gomes et al. [10] reported
3- to 5-folds increase in adhesion for polymer-modified cement pastes at 5% to 10%
p/c on concrete substrates. The microstructural images of failure interfaces showed
distinct diffusion of modified pastes to the bonded substrate, implying the formation
of monolithic bond between both materials [11]. Latexes also found particular
acceptance in reinforced concrete applications due to the resulting improvement in
bond strengths with embedded steel and resistance to corrosion and chloride ion
penetrability [9,12].
Limited attempts have been realized to incorporate polymeric latexes in concrete
containing RCA, including the extent to which such additions would help
compensating the eventual decrease in workability or drop in hardened properties.
The paper is divided in two parts; the first seeks to evaluate the suitability of SBR to
compensate the loss in concrete workability and strength as a result of 100%
replacement of NCA by RCA. Two types of RCA having different qualities were
considered; the effect of curing regime on strength development for polymer-modified
RCA concrete was also evaluated. The second phase presents the experimental load
vs. slip data obtained from beam-end specimens, along with the effect of p/c on
3. Use of SBR Latexes To Mitigate Inferior Concrete Properties Resulting From Recycled
Coarse Aggregates
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variations in bond stresses. This paper can be of interest to environmental
organizations and concrete engineers dealing with composite structures and efficient
re-use of RCA materials in the construction industry.
2. EXPERIMENTAL PROGRAM
2.1. Coarse aggregate characterization
Two RCAs having 20-mm nominal size were used; the RCA1 was obtained by
crushing returned concrete from ready-mixed batching plant, while RCA2 consisted
of crushed concrete recuperated from processing old infrastructure elements such as
manholes, concrete pipes, and culverts. Also, continuously graded crushed limestone
NCA having 20-mm nominal size was employed. The aggregates gradations were
within ASTM C33 limitations, sieve No. 67 [13].
The physical NCA and RCA properties are summarized in Table 1. The freeze-
thaw test procedure was used to determine the adhered mortar portion of RCA. The
materials were immersed in sodium sulphate solution, and subjected to five daily
cycles of freezing and thawing. After the final cycle, the sodium sulphate solution was
drained and aggregates washed and sieved over a 4.75-mm sieve. The aggregate
crushing value (ACV), reflecting the compressive strength of loose aggregate, was
determined by subjecting a measured volume of aggregate to 400-kN load [14]. After
crushing, the sample is sieved over 2.36-mm sieve where the percentage of material
passing the sieve represents the ACV (i.e., higher ACV value reflects weaker
aggregates with lower compressive strength).
2.2. Materials used for concrete production and bond testing
Portland cement conforming to ASTM C150 Type I was used; its surface area,
median particle size, and specific gravity were 355 m2
/kg, 24.7 m, and 3.14,
respectively. The natural fine aggregate consisted of well-graded siliceous sand
complying to ASTM C33 specification [13]; its bulk specific gravity, fineness
modulus, and absorption rate were 2.65, 2.5, and 0.97%, respectively. A naphthalene-
based high-range water-reducing (HRWR) admixture with specific gravity of 1.18
and solid content of 34% was used. This admixture complies with ASTM C494 Type
F; it can be used up to 3.5% of cement mass.
Table 1 Properties of NCA and RCAs used for concrete batching
Specific
gravity
Oven-dry
rodded bulk
density,
kg/m3
Absorption
rate, %
Material
finer than
75-m, %
Fineness
modulus
Adhered
mortar
content,
%
ACV,
%
NCA 2.72 1,763 0.61 0.42 6.71 n/a 17.8
RCA1 2.43 1,505 7.04 0.9 6.77 41.2 23.1
RCA2 2.4 1,497 6.12 1.16 6.84 44 28.2
Commercially available white SBR latex typically used for enhancing flexibility
and water-impermeability of cementitious materials was used. The carboxylated
styrene butadiene dispersion contains 60% of bound styrene without solvents and
stabilized using anionic emulsifying system. Its solid content, specific gravity, pH,
Brookfield viscosity (spindle 4 at 10 rpm), maximum particle size, and minimum film
forming temperature (MFFT) are 56%, 1.05, 8.5, 250 cP, 0.22 m, and -5 °C,
respectively. Relevant research studies examining the effect of SBR latexes on fresh
4. Yehia Daou and Joseph J. Assaad
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and hardened properties of cementitious materials can be seen in references 9, 10, 12,
and 15.
2.3. Concrete proportioning and mixing
Two control NCA concrete mixtures (i.e., lean and high strength) commonly used for
residential and repair applications were considered. The lean mix contained 320 kg/m3
cement with 0.56 water-to-cement ratio (w/c), while the high strength one was made
using 440 kg/m3
cement and 0.44 w/c (Table 2); the corresponding 28-days f’c was
31.6 and 54.8 MPa, respectively. The HRWR dosage was adjusted at either 0.85 % or
1.45%, respectively, of cement mass to achieve slump of 220 10 mm. The sand-to-
total aggregate ratio was set at 0.46.
Table 2 Concrete proportions using different aggregate types and SBR additions
Cement,
kg/m3
Water,
kg/m3
Net
w/c
HRWR,
% of
cement
SBR,
% of cement
mass
Coarse aggregate Fine
aggregate,
kg/m3
Type Content,
kg/m3
320 180 0.56 0.85 0 NCA 995 850
320 180 0.56 0.85 0, 1, 2, or 3 RCA1 940 800
320 180 0.56 0.85 0, 1, 2, or 3 RCA2 930 790
440 195 0.44 1.45 0 NCA 925 790
440 195 0.44 1.45 0, 2, 3, or 4 RCA1 875 745
440 195 0.44 1.45 0, 2, 3, or 4 RCA2 855 730
The effect of recycled aggregates on fresh and hardened concrete properties was
evaluated by 100% replacement of natural aggregate by RCA, with or without SBR
additions. The cement content, net w/c (given that water content in SBR was
accounted during concrete batching), HRWR dosage, and sand-to-total aggregate ratio
remained fixed as earlier described for control NCA mixtures. As can be seen in
Table 2, three SBR dosage rates of 1%, 2%, and 3% of cement mass were added in
RCA1 and RCA2 mixtures prepared with 320 kg/m3
cement, while dosages of 2%,
3%, and 4% were used in higher strength mixtures made with 440 kg/m3
cement. This
was decided following preliminary testing showing that the drop in hardened
properties is particularly accentuated in higher strength RCA concrete, making thus
more relevant the incorporation of higher latex concentrations to compensate such
losses. The corresponding p/c varied from 0.56% to 2.06%. It is to be noted that p/c
could be as high as 10% during concrete production [9,12]; however, this was limited
to 2.06% in this study because of the tangible improvement in RCA concrete
performance when compared to equivalent NCA mixtures. Also, practically speaking,
it is generally desirable to limit polymer addition rates to prevent excessive increase
in concrete cost.
Given the high RCA water absorption and eventual effect on concrete workability,
all coarse aggregates (i.e., NCA, RCA1, and RCA2) were pre-soaked for 24 hours in
water and then drained for around 1 hour prior to batching to ensure full saturation at
or above saturated-surface-dry condition [1,2,8]. The batch proportions were then
adjusted for aggregate surface moisture to maintain constant w/c. All mixtures were
prepared in an open-pan mixer of 100-Liters capacity. The mixing sequence consisted
of homogenizing the sand, aggregate, and around 50% of mixing water before
introducing the cement. After one minute of mixing, the other 45% of water was
added, followed by HRWR, and then SBR diluted in the remaining 5% of water. The
concrete was mixed for two additional minutes. The ambient temperature during
mixing and sampling hovered around 21 ±3 °C.
5. Use of SBR Latexes To Mitigate Inferior Concrete Properties Resulting From Recycled
Coarse Aggregates
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2.4. Specimen preparation and experimental testing
Part 1-Effect of SBR concentration on RCA1 and RCA2 concrete strength
Following the end of mixing, the slump, unit weight, and air content were determined
as per ASTM C143, C138, and C231 Test Methods, respectively. The fresh concrete
mixtures were then filled in 100×200 mm steel cylinders and covered by wet burlap
for 24 hours. After demolding, all concrete specimens prepared without SBR were
placed in a moist-curing room at 23 3 °C and more than 95% relative humidity (RH).
For mixtures containing SBR, the specimens were divided into two groups: the first
was wet-cured in similar manner as earlier described, while the second group was
cured for 24 hours in 95% RH, followed by air curing at 23 3 °C at 50% 5% RH, as
per ACI 548 recommendations [16]. By subjecting the specimens to various curing
conditions, the intention was to capture the effect of SBR on strength variations under
different curing conditions.
At 28 days, the compressive strength (f’c) and splitting tensile strength (ft) were
determined as per ASTM C39 and C496 Test Methods, respectively. Averages of 3
measurements are considered in this paper; the failure planes of concrete cylinders
were examined visually after crushing using a magnifying glass and classified as
being mainly around or mainly through the aggregate skeleton [8].
Part 2 Effect of SBR on bond stress vs. slip behavior
The effect of SBR additions on bond to steel behavior was determined using beam-
end specimens, as per ASTM A944 Test Method (only the RCA1 was considered in
this part). The specimen dimensions measured 220 mm in width, 250 mm in length,
and 220 mm in height, as shown in Fig. 1 [17]. Deformed steel bars complying to
ASTM A615 No. 13 with nominal diameter (db) of 12.7 mm was used; the Young’s
modulus and yield strength (fy) were 203 GPa and 428 MPa, respectively. The
specimen is positioned in a test rig so that the bar can be pulled slowly from concrete;
it is restrained from translation through a compression reaction plate and restrained
from rotation through a tie-down, thus approximating boundary conditions of simply
supported beams.
All bars were embedded inside the specimens at fixed lengths of 5db (i.e., 60 mm)
to prevent yielding of steel; similar rib orientation with respect to pullout load was
maintained in all specimens. The concrete clear cover was kept constant at 40 mm; a
size typically used in the design of flexural beams. Two stirrups with 9.5-mm nominal
diameter were placed on each side were provided for shear resistance, but were
oriented parallel to the “pull” direction to avoid confining the test bar along its bonded
length. The concrete samples were placed in two consecutive lifts in the beam-end
specimen molds, and internally vibrated using 150-Hz frequency vibrator. Before
testing, the specimen was shimmed and aligned so that the test bar is parallel to the
loading frame. The tensile load was gradually applied at a rate of 25 ±4 kN per minute
until bond failure occurred. The bar’s relative slips to concrete were monitored from
measurements of two LVDTs placed at the free and loaded bar surfaces (Fig. 1).
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Figure 1 Set-up used for determining bond using beam-end specimens
3. TEST RESULTS AND DISCUSSION
3.1. Part 1: Effect of SBR concentration and curing regime on concrete
properties
3.1.1 Air content and workability
The fresh and hardened properties of tested concrete mixtures are summarized in
Table 3. Generally, the air content of fresh concrete prepared with RCA1 or RCA2
did not vary considerably with respect to corresponding NCA mixture (Table 3).
Nevertheless, this followed an increasing trend with SBR additions; for example, such
increase was from 2.8% for 440-RCA1 mix prepared without polymer to 3.5% and
4.1% when the SBR was added at 3% and 4% rates, respectively. This could be
related to the surfactants added to stabilize the polymer including their inherent
surface activity (i.e., ability to reduce surface tension of water) and solubility in the
high cement pH solution [9].
As expected, the use of RCA1 and RCA2 led to reduced workability when
compared to equivalent NCA mixture (Table 3). For example, such reduction reached
155 and 160 mm for RCA1 concrete prepared with 320 or 440 kg/m3
cement,
respectively. This can mostly be attributed to the angular and roughened surface
texture of recycled aggregates that increased internal friction in fresh concrete [1,3].
Nevertheless, the incorporation of increased polymer additions led to improved
workability, which can be related to the ball bearing and plasticizing effects resulting
from the polymer spherical shapes [9,15]. For example, the slump increased from 160
mm for 440-RCA1 concrete prepared without polymer to 205 and 210 mm with 3%
and 4% SBR additions, respectively. Additionally, it is to be noted that the
improvement in flow can partly be attributed to increased amounts of air entrainment
in the polymer-modified concrete.
3.1.2 Effect of curing regime on hardened polymer-modified RCA concrete strength
The ratios of f’c determined from specimens cured in air conditions with respect to
those wet-cured in 95% RH are plotted in Fig. 2 for all RCA concrete mixtures
containing various percentages of SBR polymers. The figure also plots the ratios of ft
values. With some few exceptions, it is clear that the development of strengths is
affected by the curing regime, whereby specimens cured in air conditions exhibiting
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up to 13% more strength. Such results are in agreement with other findings reported
in literature [16]. In fact, after initial moist curing for 24 hours, the latex particles
coalesce into films that become adsorbed onto the surfaces of hydrated cement
compounds, preventing further moisture loss (i.e., entrapped moisture promotes
cement hydration processes). Concurrently, as the latex films develop, reactive groups
in the polymer crosslink within the internal structure, forming continuous and
impermeable coating film layers (i.e., such films are destabilized under wet curing)
[9,17]. Hence, the increase in strength encountered under air curing conditions can be
associated to an increase in both cement hydration reactions as well as polymer
crosslinking.
Table 3 Effect of SBR concentration and curing regime on concrete properties
Mixture
codification
p/c,
%
Slump,
mm
Air
content,
%
Unit
weight,
kg/m3
Wet-cured at
95% RH for 28
days
Cured at 95% RH
for 24 hours, then
air-cured for 27
days
f’c,
MPa
ft,
MPa
f’c,
MPa
ft,
MPa
320-NCA 0 220 2.6 2335 31.6 3.77 n/a n/a
320-RCA1 0 155 2.35 2315 29.8 3.5 n/a n/a
320-RCA1-1%SBR 0.56 160 2.8 2345 31.3 3.87 30.9 3.92
320-RCA1-2%SBR 1.12 180 3.2 2310 33.9 4.17 35 4.51
320-RCA1-3%SBR 1.68 195 3.3 2290 34.2 4.3 35.8 4.73
320-RCA2 0 135 2.8 2290 23.9 2.97 n/a n/a
320-RCA2-1%SBR 0.56 135 2.75 2310 26.1 3.36 28 3.6
320-RCA2-2%SBR 1.12 165 3.15 2310 28.4 3.97 30 4.11
320-RCA2-3%SBR 1.68 190 3.5 2285 30.1 4.06 33.1 4.6
440-NCA 0 225 2.4 2380 54.8 6.2 n/a n/a
440-RCA1 0 160 2.8 2355 46.4 5.4 n/a n/a
440-RCA1-2%SBR 1.12 185 2.8 2345 47.8 6.5 47.5 6.42
440-RCA1-3%SBR 1.68 205 3.5 2315 49.5 6.76 51.2 6.8
440-RCA1-4%SBR 2.06 210 4.1 2290 53 7.03 56 7.1
440-RCA2 0 125 2.7 2350 39.6 4.46 n/a n/a
440-RCA2-2%SBR 1.12 135 3 2310 47.2 5.5 46.5 5.66
440-RCA2-3%SBR 1.68 170 3.8 2285 46 6.12 49.2 6.7
440-RCA2-4%SBR 2.06 185 4.3 2270 50.8 6.63 54.4 7.2
n/a refers to not applicable
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Figure 2 Effect of curing regime on f’c and ft of SBR-modified RCA concrete
3.1.3 Effect of SBR on variations in f’c and ft
The variations in hardened properties for concrete mixtures containing RCA1 with or
without SBR are plotted in Fig. 3. The (Property) was normalized with respect to
corresponding control NCA concrete made with either 320 or 440 kg/m3
cement, as
follows:
A. Compressive strength
Concrete made without polymers – As can be seen, the complete NCA substitution by
RCA1 led to reduced f’c, particularly for high strength mixtures prepared with 440
kg/m3
cement. Hence, this varied from -5.7% to -15.3% for concrete made with 320
or 440 kg/m3
cement, respectively. Such results are in agreement with those reported
by Butler et al. [8] who associated the drop in f’c of lean and high strength RCA
concrete to different failure planes occurring around or through the coarse aggregate
skeleton. In fact, the visual examination of crushed concrete cylinders made with 320
kg/m3
cement showed distinct failure planes occurring mainly around the aggregate
particles, suggesting that the ITZ between mortar-aggregate is the limiting strength
factor. In contrast, the failure planes become less distinct and mostly passing through
the aggregate particles for concrete prepared with 440 kg/m3
, implying that the
strength of RCA itself is the limiting factor [1,8].
Effect of SBR on (f’c) – Clearly, the use of increased SBR concentration
improved f’c of RCA1 mixtures, albeit this varied depending on cement content and
strength of original concrete (Fig. 3). For example, (f’c) increased significantly from
-5.7% for lean 320-RCA1 concrete made without SBR to +7.3% and +8.2% for
equivalent mixtures containing 2% or 3% SBR, respectively. This can be attributed to
the polymer particles that strengthen the mortar-aggregate interface, especially
knowing that f’c of lean concrete is mostly governed by the ITZ behavior. In contrast,
the (f’c) increase in high strength concrete prepared with 440 kg/m3
cement was
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much less pronounced, and remained in the negative region. Hence, (f’c) varied from
-15.3% for 440-RCA1 concrete made without SBR to -9.7% and -3.3% for mixtures
containing 3% and 4% SBR, respectively. This practically suggests that the beneficial
polymer effect on compressive strength of recycled aggregate concrete is directly
affected by the mixture proportioning.
Figure 3 Effect of SBR on variations in f’c and ft for concrete containing RCA1
B Splitting tensile strength
Unlike (f’c), the incorporation of SBR polymers led to gradually increased ft values,
even much higher than corresponding NCA concrete. For example, (ft) reached
+14.1% and +8.9% for RCA1 mixtures made with 320 or 440 kg/m3
cement,
respectively, containing 3% SBR. In fact, it is well accepted that structure of hardened
cement paste is mainly composed of agglomerated calcium silicate hydrates and
calcium hydroxide bound together by weak van der Waals forces, whereby
microcracks could occur easily under stress leading to poor tensile strength [9].
Hence, in latex-modified systems, the microcracks are bridged by the polymer films
that prevent crack propagation in hardened ITZ, resulting in stronger cement hydrate-
aggregate bond. Additionally, the improved smoothness and flowability of modified
RCA concrete are expected to reduce porosity of ITZ and develop increased bond by
micro-mechanical interlocking mechanisms [11].
3.1.4 Effect of p/c and comparison between RCA1 vs. RCA2
The relationships between p/c with respect to (f’c) and (ft) determined on concrete
mixtures prepared using RCA1 and RCA2 cured under air conditions are plotted in
Fig. 4. Clearly, the incorporation of SBR (i.e., higher p/c) led increased strength
development, albeit this appears to be significantly affected by the type of RCA used.
As can be seen, the tendency curves obtained from concrete containing RCA1 are
consistently higher than those resulting from RCA2 concrete. This could be directly
related to the quality of recycled aggregates (i.e., note that RCA1 was of better quality
than RCA2, the resulting ACV was 23.1% vs. 28.2%, respectively). Hence, the
threshold p/c beyond which f’c becomes equivalent to NCA mixture decreased from
around 2% to 1.2% with the use of RCA2 and RCA1, respectively. For ft, such
decrease was from around 1.4% to 0.9%, respectively. Practically speaking, this
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clearly shows the importance of RCA quality on the development of concrete
strength.
3.2 Phase II: Effect of SBR additions on bond stress vs. slip behavior
Table 4 summarizes the bond characteristics of tested concrete including the bond
stresses corresponding to slip of 0.01 and 0.1 mm (0.01mm and 0.1mm, respectively),
ultimate bond stress (u) representing the maximum load at failure, and slip at free-
end (δu) coinciding with the ultimate load. Also, the normalized bond stress calculated
as the ratio of u to the square root of f’c is given. It is to be noted that all tests
exhibited pullout modes of failure characterized by crushing and shearing of the
localized embedded region around the bar. No cracks were observed on their external
surfaces, indicating that the concrete cover provided adequate confinement [17].
3.2.1-Bond stress vs. slip curves of tested mixtures
The vs. δ curves determined for control NCA concrete prepared with 320 kg/m3
cement as well as those made using RCA1 with or without SBR additions are given in
Fig. 5.
Comparison between NCA vs. RCA1 concrete behavior (without SBR) –
Concurrent with existing literature [8,9,10,12], the substitution of NCA by RCA1 did
not result in considerable changes in τ vs. δ curves. Hence, the three mechanisms
controlling the bond between steel and concrete including adhesion, mechanical
interlock, and friction can be well identified [7]. Nevertheless, it is to be noted that u
at failure for RCA1 concrete was relatively lower than equivalent value determined
using NCA mixture, especially for higher strength concrete prepared with 440 kg/m3
cement. For example, u decreased from 11.8 to 11.4 MPa and from 16.3 to 14.7 MPa
for mixtures made with 320 and 440 kg/m3
cement, respectively (Table 4). This can
be directly attributed to the reduced RCA1 concrete hardened properties including f’c
and ft, thus reducing the material’s bearing strength capacity in front of the bar ribs.
Figure 4 Effect of p/c and RCA1 vs. RCA2 on variations in f’c and ft
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Table 4 Effect of SBR on bond stress vs. slip concrete properties
Mixture codification 0.01mm,
MPa
0.1mm,
MPa
u,
MPa
δu,
mm
u / (f’c)0.5
320-NCA 2.54 7.13 11.8 0.53 2.1
320-RCA1 2.3 6.65 11.4 0.55 2.09
320-RCA1-1%SBR 2.7 7.45 12.8 0.71 2.29
320-RCA1-2%SBR 3.05 9 13 0.9 2.23
320-RCA1-3%SBR 4.6 8.77 14.1 0.88 2.41
440-NCA 3.85 9.6 16.3 0.48 2.2
440-RCA1 3.24 7.8 14.7 0.48 2.16
440-RCA1-2%SBR 5.3 12.7 17.1 0.92 2.47
440-RCA1-3%SBR 7.2 14 18.7 0.9 2.66
440-RCA1-4%SBR 9.7 16.1 21.4 1.32 2.94
Figure 5 Typical bond stress vs. slip curves for mixtures made with 320 kg/m3
cement
Behavior of RCA1 concrete containing SBR – Clearly, the bars free-end of
polymer-modified RCA1 concrete started to slip at bond stresses higher than those of
control mixtures, thus accentuating the initial stiffness of vs. δ curves (Fig. 5). For
example, at the very small slip of 0.01 mm, 0.01mm increased from 2.3 MPa for 320-
RCA1 concrete prepared without SBR to 3.05 and 4.6 MPa with the addition of 2% or
3% SBR, respectively (Table 4). This can be directly attributed to the latex polymers
that increase the adhesive component in the elastic region and result in increased
interfacial shear stresses between the reinforcing bar and surrounding concrete [12].
Ohama [9] related this phenomenon to the presence of electro-chemically active
polymer-cement co-matrixes at the interfaces with reinforcing bars, thus relaxing the
stresses during loading and retarding the friction-controlled slip of rebars.
When the adhesive component of bond fails, the responses of ascending curves of
SBR-modified concrete showed extended non-linear regions together with higher u,
which can be explained by more pronounced compressive strain-softening
phenomenon due to the presence of polymer latexes [7]. For example, δu increased
from 0.55 mm for 320-RCA1 concrete prepared without SBR to 0.88 mm with 3%
12. Yehia Daou and Joseph J. Assaad
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SBR; the corresponding u increased from 11.4 MPa to 13 MPa (Table 4). In fact, the
bond resistance in beam-end specimen is achieved by circumferential tension stresses
created in the concrete around the bar; if these forces exceed the tensile concrete
capacity, failure occurs [7,8,12]. Therefore, given that ft of RCA1 concrete is
significantly improved with polymer additions, this can reduce the propagation of
microcracks and result in increased bond resistance with reinforcing bar.
3.2.2 Relationships between p/c and bond properties
The relationships between p/c with respect to 0.01mm, 0.1mm, and u are plotted in Fig.
6. As can be seen, RCA1 concrete incorporating higher SBR additions (i.e., higher
p/c) led to increased bond stresses. Nevertheless, such increase was particularly
accentuated for 0.01mm, suggesting that the adhesive component of bond could be
highly improved by such additions. For example, at the highest p/c of 2.06%,
(0.01mm) reached 152%, while (0.1mm) and (u) reached respectively 68% and
31%.
From the other hand, it is to be noted that the slips at failure shifted gradually
towards higher values with increased p/c. The resulting correlation can be written as:
Slip at free-end, mm = 0.309 (p/c, %) + 0.51, with R2
of 0.88. Practically, this
indicates that the structural ductility of reinforced RCA concrete members tends to
increase with polymer additions [12]. The ratio of u to the square root of f’c followed
an increasing trend with p/c; the relationship can be written as: Ratio = 0.296 (p/c, %)
+ 2.11, with R2
of 0.78.
Figure 6 Relationships between p/c with respect to bond stresses
4. SUMMARY AND CONCLUSIONS
The use of RCA in structural concrete applications is very limited, given the concerns
pertaining to its inferior mechanical properties when compared to natural aggregate
concrete. The main objective of this paper is to evaluate the effect of SBR polymers
on RCA concrete properties and, consequently, bond to embedded steel bars.
Based on foregoing, test results have shown that the incorporation of SBR can
remarkably improve RCA concrete workability due to ball bearing and plasticizing
effects. On the hardened state, such additions led to increased f’c and ft, particularly
for lean mixtures made with 320 kg/m3
cement, which practically implies that
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polymeric latexes can effectively compensate the loss in RCA concrete performance.
The improvement in strength was further accentuated when curing was realized for 24
hours in 95% RH, and then for 27 days in air conditions at 23 3 °C and 50% 5%
RH.
The mechanisms of bond failure in vs. δ curves recorded using SBR-modified
RCA concrete are fundamentally similar to those observed with natural aggregate
concrete. Yet, the initial stiffness was considerably accentuated with SBR additions,
reflecting increased interfacial shear stresses between the reinforcing bar and
surrounding concrete. Also, the ascending curves showed extended non-linear regions
together with higher u. Good correlations were established between p/c and bond
properties.
ACKNOWLEDGMENTS
This project was funded by the School of Engineering Research Council of the
Lebanese University (LU), Hadath, Lebanon. The authors wish to acknowledge the
experimental support provided by the Laboratory of the Civil Engineering Department
at LU as well as the contributions of research assistants from Finders SAL, Amchit,
Lebanon.
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