This webinar discusses shrinkage in concrete and remedies. It covers various types of shrinkage like plastic, autogenous, drying, thermal and carbonation shrinkage. Factors influencing shrinkage like mix proportions, material properties and curing conditions are explained. Strategies to reduce plastic shrinkage cracking include moistening aggregates, erecting sunshades and applying curing compounds. Autogenous shrinkage can be significant in low water-cement ratio mixtures. Drying shrinkage is influenced by specimen size and aggregate properties. Mitigation methods covered are shrinkage reducing admixtures, expansive cements and lightweight aggregates. Contraction joints are important to control thermal shrinkage cracking in thick structures.
This document discusses the use of bacterial concrete, which uses microbiologically-induced calcium carbonate precipitation to improve the properties of concrete. Various bacteria like Bacillus pasteurii and Bacillus sphaericus are able to continuously precipitate calcium carbonate. Bacterial concrete has been shown to increase the compressive, tensile, and flexural strength of concrete by up to 25% compared to conventional concrete. It can also help reduce cracks and improve the strength regeneration of cracked concrete. The cost of bacterial concrete is only 4-5% higher than conventional concrete. Scanning electron microscope images provide evidence of calcite precipitation in cracks by the bacteria.
This document summarizes chapter 4 of the book "Structural Concrete Design" which covers various topics related to designing structural concrete including:
- Properties of concrete and reinforcing steel such as compressive strength, modulus of elasticity, creep, and tensile strength.
- Proportioning and mixing concrete, including using admixtures.
- Flexural and strength design of beams, slabs, columns, shear/torsion, development of reinforcement, two-way systems, frames, brackets/corbels, and footings.
- Additional concrete types such as lightweight and high-strength concrete.
This chapter discusses structural concrete design. It covers properties of concrete and reinforcing steel, proportioning and mixing concrete, flexural design of beams and slabs, columns under bending and axial load, shear and torsion, development of reinforcement, two-way systems, frames, brackets and corbels, footings, walls, and defining terms. The chapter aims to promote a unified approach to structural concrete design across different design approaches, techniques, and codes worldwide.
This study experimentally investigated the effects of Millenium 21 internal curing admixture on the durability and strength of concrete. Compressive strength, carbonation, and water absorption tests were performed on conventionally cured and internally cured concrete specimens at various ages. The results showed that internally cured concrete specimens had higher compressive strength at 7, 28, and 120 days compared to conventionally cured specimens. Carbonation depth was also lower in internally cured specimens at 120 days. Additionally, internally cured specimens exhibited reduced water absorption compared to conventionally cured specimens, indicating improved durability. The findings demonstrate that internal curing with Millenium 21 can enhance long-term strength and durability of concrete.
IRJET - Correlation of Chloride Solution Absorption-Time in Pre-Condition...IRJET Journal
This document summarizes a research study that investigated chloride absorption in pre-conditioned dry concrete cubes (DCC) with different mixture designs. Seventy-two 100mm concrete cubes were cast with six mixtures that varied compressive strength, water-cement ratio, and slump. Cubes were submerged in 10% NaCl solution for 160 days and weighed periodically to determine chloride absorption. Results showed chloride absorption increased over time and was lower in solvent-based and water-based impregnated cubes compared to control DCC cubes. Chloride absorption also decreased with increasing compressive strength and was correlated to time using logarithmic expressions for all cube types. The study aimed to characterize the influence of dry conditions and impregnation
This document summarizes research on self-healing concrete. It describes tests performed on conventional concrete and concrete containing bacteria. The bacterial concrete showed improved tensile strength, compressive strength, and decreased water and gas permeability compared to conventional concrete. A mathematical model is presented for the stress-strain behavior of both concretes. The experimental data matched the theoretical model closely. In conclusion, the addition of bacteria improved several properties of the concrete by autonomously repairing cracks.
1) The study evaluated the abrasion resistance of three concrete materials - a standard concrete mixture, a latex polymer repair material, and a silica fume repair material - when exposed to water-borne sand.
2) Testing found that the silica fume material exhibited the best abrasion resistance, followed by the latex polymer material, with the standard concrete mixture performing the worst. Abrasion loss decreased with increasing concrete age and increased with longer exposure times.
3) Both compressive and flexural strength were strongly correlated with abrasion rate, with higher strength materials exhibiting less abrasion. The silica fume mixture also showed the lowest abrasion depth, making it the most abrasion resistant material tested.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This document discusses the use of bacterial concrete, which uses microbiologically-induced calcium carbonate precipitation to improve the properties of concrete. Various bacteria like Bacillus pasteurii and Bacillus sphaericus are able to continuously precipitate calcium carbonate. Bacterial concrete has been shown to increase the compressive, tensile, and flexural strength of concrete by up to 25% compared to conventional concrete. It can also help reduce cracks and improve the strength regeneration of cracked concrete. The cost of bacterial concrete is only 4-5% higher than conventional concrete. Scanning electron microscope images provide evidence of calcite precipitation in cracks by the bacteria.
This document summarizes chapter 4 of the book "Structural Concrete Design" which covers various topics related to designing structural concrete including:
- Properties of concrete and reinforcing steel such as compressive strength, modulus of elasticity, creep, and tensile strength.
- Proportioning and mixing concrete, including using admixtures.
- Flexural and strength design of beams, slabs, columns, shear/torsion, development of reinforcement, two-way systems, frames, brackets/corbels, and footings.
- Additional concrete types such as lightweight and high-strength concrete.
This chapter discusses structural concrete design. It covers properties of concrete and reinforcing steel, proportioning and mixing concrete, flexural design of beams and slabs, columns under bending and axial load, shear and torsion, development of reinforcement, two-way systems, frames, brackets and corbels, footings, walls, and defining terms. The chapter aims to promote a unified approach to structural concrete design across different design approaches, techniques, and codes worldwide.
This study experimentally investigated the effects of Millenium 21 internal curing admixture on the durability and strength of concrete. Compressive strength, carbonation, and water absorption tests were performed on conventionally cured and internally cured concrete specimens at various ages. The results showed that internally cured concrete specimens had higher compressive strength at 7, 28, and 120 days compared to conventionally cured specimens. Carbonation depth was also lower in internally cured specimens at 120 days. Additionally, internally cured specimens exhibited reduced water absorption compared to conventionally cured specimens, indicating improved durability. The findings demonstrate that internal curing with Millenium 21 can enhance long-term strength and durability of concrete.
IRJET - Correlation of Chloride Solution Absorption-Time in Pre-Condition...IRJET Journal
This document summarizes a research study that investigated chloride absorption in pre-conditioned dry concrete cubes (DCC) with different mixture designs. Seventy-two 100mm concrete cubes were cast with six mixtures that varied compressive strength, water-cement ratio, and slump. Cubes were submerged in 10% NaCl solution for 160 days and weighed periodically to determine chloride absorption. Results showed chloride absorption increased over time and was lower in solvent-based and water-based impregnated cubes compared to control DCC cubes. Chloride absorption also decreased with increasing compressive strength and was correlated to time using logarithmic expressions for all cube types. The study aimed to characterize the influence of dry conditions and impregnation
This document summarizes research on self-healing concrete. It describes tests performed on conventional concrete and concrete containing bacteria. The bacterial concrete showed improved tensile strength, compressive strength, and decreased water and gas permeability compared to conventional concrete. A mathematical model is presented for the stress-strain behavior of both concretes. The experimental data matched the theoretical model closely. In conclusion, the addition of bacteria improved several properties of the concrete by autonomously repairing cracks.
1) The study evaluated the abrasion resistance of three concrete materials - a standard concrete mixture, a latex polymer repair material, and a silica fume repair material - when exposed to water-borne sand.
2) Testing found that the silica fume material exhibited the best abrasion resistance, followed by the latex polymer material, with the standard concrete mixture performing the worst. Abrasion loss decreased with increasing concrete age and increased with longer exposure times.
3) Both compressive and flexural strength were strongly correlated with abrasion rate, with higher strength materials exhibiting less abrasion. The silica fume mixture also showed the lowest abrasion depth, making it the most abrasion resistant material tested.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This document investigates using coffee husk ash as a partial replacement for cement in concrete with a grade of C25. The objectives were to determine the workability and strength properties of concrete mixes containing different percentages of coffee husk ash. Testing showed that as the percentage of coffee husk ash increased, workability and compressive strength decreased while tensile strength initially increased up to 20% replacement before decreasing. The bulk density also decreased with higher coffee husk ash content. The conclusion was that a 5% replacement of cement with coffee husk ash provided benefits to strength without significantly impacting workability.
Review Use of Demolished Concrete in Pavement Constructionijtsrd
Recycled aggregates consist of crushed, graded inorganic particles processed from the material that have been used in the constructions and demolition debris. The target of the present thesis work is to determine the strength characteristic of recycled aggregates for the application in concrete pavement construction. The scope of the thesis is to determine and compare the compressive strength, flexural strength and sulphate resistance of concrete by using different percentages of recycled aggregates. The investigation was carried out by using workability test, compressive strength test, flexural strength test and sulphate resistance test. A total of five mixes with replacement of coarse aggregates with 0%, 10%, 20%, 30% and 40% recycled coarse aggregates were studied. The water cement ratio was kept constant at 0.38. It was observed that workability of concrete was decreased with the increase in recycled aggregates in concrete. For the strength characteristics, the results showed that the strengths of recycled aggregate concrete was comparable to the strengths of natural aggregates concrete. Munesh Kumar | Sumesh Jain"Review Use of Demolished Concrete in Pavement Construction" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-5 , August 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2368.pdf http://www.ijtsrd.com/engineering/civil-engineering/2368/review-use-of-demolished-concrete-in-pavement-construction/munesh-kumar
Nanotechnology in Building construction materialRinoy Bhagora
Nanotechnology can be used to improve the properties of concrete and other construction materials. The addition of nano-silica or carbon nanotubes to concrete can increase its strength and durability by densifying its microstructure. A self-cleaning glass called Indigo Tower uses a titanium dioxide nano-coating that breaks down air pollutants using a photocatalytic process, powered by sunlight. Nanoparticles can also strengthen steel by reducing fatigue and embrittlement. Fire-protective glass uses silica nanoparticles to form a heat shield, and nano-coatings on regular glass aim to filter infrared light and regulate heat gain in buildings.
IRJET - Comparative Study of Chloride Absorption in Pre-Conditioned Concrte C...IRJET Journal
This document summarizes a research study that compares chloride absorption in pre-conditioned concrete cubes with different concrete mixtures. Seventy-two concrete cubes were prepared with six different mixtures that varied slump, water-cement ratio, and compressive strength. Cubes were pre-conditioned to be dry, fully saturated, or partially saturated. Cubes were then exposed to a 10% sodium chloride solution for 160 days. Chloride absorption was analyzed at various time intervals. Results showed that chloride absorption varied depending on pre-conditioning, mixture properties, and exposure duration. Absorption increased over time and was higher in dry pre-conditioned cubes compared to saturated cubes. Impregnated cubes generally had lower absorption than
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Improvement on the concrete cracks by using Bacillus pastueriiijsrd.com
Cracks in concrete are irreversible and are one of the naturally weaknesses of concrete. Bacillus Pasteruii, a common soil bacterium induce the precipitation of calcite exhibited its positive potential in selectively consolidating simulated fractures in the consolidation of sand. A compression, flexural and durability tested on mortar cubes and concrete beams treated with bacteria were studied. The effect of different depth of crack on the compression, flexural and durability of concrete was studied. It was found that all the increase in depth of crack reduce the strength of cubes and beams.
Traditional Concrete Compositions to Cutting Edge Solutions..pptxSARANYA KANDASAMY
The transition from traditional concrete compositions to cutting-edge solutions represents a dynamic
evolution in the field of construction. This journey encompasses a spectrum of advancements, bridging
time-honored practices with innovative technologies to shape the built environment. From the basic mixture of cement, aggregates, and water to the integration of specialized additives, fibers, and nano materials, this progression signifies a pursuit of enhanced strength, durability, sustainability, and
functionality.At one end of the spectrum, traditional concrete compositions rely on well-established proportions of
components to create structures that have served humanity for centuries. This approach emphasizes the tried-and-true principles of concrete technology, providing stability and reliability in various applications.
IRJET- Internal Curing of Concrete using Pre Wetted Light Weight AggregatesIRJET Journal
The document summarizes a study on the use of pre-wetted lightweight aggregates for internal curing of concrete to improve its properties. It found that replacing 10% of coarse aggregates with expanded clay led to higher compressive strength, split tensile strength, and degree of hydration compared to normal concrete due to the water stored in the lightweight aggregates helping to cure the concrete from within. The optimum replacement was found to be 10% lightweight aggregate, beyond which strengths started decreasing. Internal curing produced a denser microstructure and reduced cracking compared to traditional external curing.
The document discusses materials used in reinforced concrete structures, including concrete, steel reinforcement, and their properties. It provides three key points:
1) Concrete quality is measured by strength and durability, which depend on water-cement ratio, aggregates, and hydration. Workability and economy are also important considerations in mix design.
2) Steel reinforcement commonly used includes deformed bars and welded wire fabric in various grades depending on the yield strength required.
3) The properties of both concrete and steel, such as stress-strain behavior, modulus of elasticity, creep, and shrinkage, influence the design and performance of reinforced concrete structures.
IRJET - Durability of Concrete with Differential Concrete Mix DesignIRJET Journal
The document discusses the durability of concrete with different concrete mix designs. It presents research on how water absorption, density, and sorptivity coefficient are affected by varying the water-cement ratio, slump, and compressive strength in concrete mixes. Seventy-two concrete cubes were prepared with six different mix designs - three mixes varied the slump and water-cement ratio at a constant compressive strength, while three other mixes varied the compressive strength and water-cement ratio at a constant slump. The cubes were tested to determine their rate of water absorption, density, and sorptivity coefficient at various time intervals over 28 days. The results showed that the sorptivity coefficient and rate of water absorption
This manuscript is about the concrete specification. The concrete specification testing is a process by which different tests are carried out such as compressive strength, carbonation depth, ASTM rapid chloride permeability, NDT chloride and initial surface absorption test (ISAT-10) to determine the quality and performance of the concrete in terms of strength, carbonation depth, chloride permeability and surface absorption.
Shrinkage Characterization of Cement Concrete with Various Supplementary Ceme...IRJET Journal
This document reviews the effects of supplementary cementitious materials (SCMs) and fibers on the shrinkage characteristics of concrete. It discusses the different types of shrinkage that can occur in concrete, including plastic, drying, and autogenous shrinkage. The use of SCMs like fly ash, slag, and silica fume are found to reduce shrinkage by replacing cement and participating in pozzolanic reactions. Fibers are also found to reduce shrinkage by providing a restraint against cracking. Super absorbent polymers can be used for internal curing to control shrinkage. Test methods for measuring shrinkage and other concrete properties are also outlined.
An Experimental Study on Rapid Chloride Penetration Test of Self Compacting C...ijtsrd
Self compacting concrete SCC is a very fluid concrete and a homogeneous mixture that solves most of the problems related to ordinary concrete. Self Compacting Concrete gets dense and compacted due to its own self weight. An experimental investigation has been carried out to determine different characters like filling ability, passing ability, segregation resistance workability and strength of Self Compacting Concrete SCC . And finally determining the chloride penetrability of SCC. Self Compacted Concrete is generally defined as the “Concrete, which does not need Compaction.†Due to these characteristics, SCC is ideally suited for concreting structures, which have heavily congested reinforcement or difficult access conditions. In this project, M40 grade concrete were made using European method. The compressive strength, split tension test obtained at the ages of 7, 14 and 28 days. Mr. R. Jeya Prakash | Ms. R. Nirmala ""An Experimental Study on Rapid Chloride Penetration Test of Self Compacting Concrete"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-3 , April 2019, URL: https://www.ijtsrd.com/papers/ijtsrd21650.pdf
Paper URL: https://www.ijtsrd.com/engineering/civil-engineering/21650/an-experimental-study-on-rapid-chloride-penetration-test-of-self-compacting-concrete/mr-r-jeya-prakash
1) The document discusses causes, prevention, and repair of concrete cracks. It identifies three main factors that cause cracks: internal and external stratification during concrete pouring, the transition zone between concrete and aggregate, and the multiphase porous system in cement.
2) Prevention methods discussed include controlling water-cement ratio, adding silica fume, and using high-quality aggregate.
3) Repair methods summarized are surface filling of small cracks, pressure grouting of larger cracks, and caulking of even larger cracks. The document concludes that structural defects during concrete pouring are the underlying cause of cracks.
On causes, prevention and repairing measures of concrete cracksIJERA Editor
At present, domestic and overseas researches on concrete cracks mainly focus on the formation of cracks from external factors, such as cracks caused by temperature, external loads and uneven settlement of foundation. Based on other scholars’ study on the reason and settlement of cracks, this paper starts from the defect of concrete structure, and proposes three factors affecting concrete cracks: internal and external stratification during the process of concrete placement, the presence of the transition zone of concrete and multiphase porous system of the cement. In addition, the author has summarized the prevention and repairing measures of cracks.
This document summarizes the key aspects of shotcrete, including its classification, materials, processes, specifications, and a case study on health and safety. Shotcrete is a sprayed concrete used for constructing curved surfaces like tunnels. It is conveyed through a hose and pneumatically projected. The case study examines efforts across various countries to reduce dust exposure for shotcrete workers, including improving shotcrete mixtures and equipment to reduce dust production and using personal protective equipment. Further research is still needed to improve worker health and safety.
Curing Methods and Their Effects on The Strength of ConcreteIJERA Editor
There are a lot of arguments on which method of curing concrete gives good strength. These different opinions results into this study, which aim at investigating the effects of different curing methods on the strength of concrete. Laboratory test was employed for this study. Normal concretes were prepared using specified mix ratio of 1:2:4 and 1:3:6. The cubes tested for compressive strength at 3, 7, 21, and 28 days of curing respectively using four curing methods namely immersion, sprinkling, polythene sheeting and sharp sand coating. Testing indicate that water immersion curing method as well as sprinkling (spraying ) methods of curing, provide better results than membrane (polythene sheeting) method of curing. While sharp sand gives least strength. The rate of drying was significant when the specimens were subjected to curing with polythene sheet method of curing. This thus hampered the hydration process and thus affected the compressive strength property of the hardened concrete. The overall findings of this study suggests that concrete should be cured by water immersion or spraying regularly to achieve a better compressive strength in concrete.
IRJET - Effectiveness of Concrete Ingredients on Isat in DCC CubesIRJET Journal
This document discusses a study that assessed the effectiveness of different concrete ingredients on initial surface absorption test (ISAT) values in dry conditioned concrete cubes. Six different concrete mixtures were prepared varying slump, water-cement ratio, and compressive strength. ISAT tests were conducted on 72 concrete cubes according to BS 1881 standards after drying for 3 days at 105±5°C. The results showed that ISAT values increased at initial testing for mixtures with lower compressive strength and water diffusion coefficient, and decreased with higher strength, constant slump, and over time. Higher water-cement ratios and slump also increased ISAT values. The study aimed to interpret the influence of drying conditions and mixture proportions on ISAT results.
This document investigates using coffee husk ash as a partial replacement for cement in concrete with a grade of C25. The objectives were to determine the workability and strength properties of concrete mixes containing different percentages of coffee husk ash. Testing showed that as the percentage of coffee husk ash increased, workability and compressive strength decreased while tensile strength initially increased up to 20% replacement before decreasing. The bulk density also decreased with higher coffee husk ash content. The conclusion was that a 5% replacement of cement with coffee husk ash provided benefits to strength without significantly impacting workability.
Review Use of Demolished Concrete in Pavement Constructionijtsrd
Recycled aggregates consist of crushed, graded inorganic particles processed from the material that have been used in the constructions and demolition debris. The target of the present thesis work is to determine the strength characteristic of recycled aggregates for the application in concrete pavement construction. The scope of the thesis is to determine and compare the compressive strength, flexural strength and sulphate resistance of concrete by using different percentages of recycled aggregates. The investigation was carried out by using workability test, compressive strength test, flexural strength test and sulphate resistance test. A total of five mixes with replacement of coarse aggregates with 0%, 10%, 20%, 30% and 40% recycled coarse aggregates were studied. The water cement ratio was kept constant at 0.38. It was observed that workability of concrete was decreased with the increase in recycled aggregates in concrete. For the strength characteristics, the results showed that the strengths of recycled aggregate concrete was comparable to the strengths of natural aggregates concrete. Munesh Kumar | Sumesh Jain"Review Use of Demolished Concrete in Pavement Construction" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-5 , August 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2368.pdf http://www.ijtsrd.com/engineering/civil-engineering/2368/review-use-of-demolished-concrete-in-pavement-construction/munesh-kumar
Nanotechnology in Building construction materialRinoy Bhagora
Nanotechnology can be used to improve the properties of concrete and other construction materials. The addition of nano-silica or carbon nanotubes to concrete can increase its strength and durability by densifying its microstructure. A self-cleaning glass called Indigo Tower uses a titanium dioxide nano-coating that breaks down air pollutants using a photocatalytic process, powered by sunlight. Nanoparticles can also strengthen steel by reducing fatigue and embrittlement. Fire-protective glass uses silica nanoparticles to form a heat shield, and nano-coatings on regular glass aim to filter infrared light and regulate heat gain in buildings.
IRJET - Comparative Study of Chloride Absorption in Pre-Conditioned Concrte C...IRJET Journal
This document summarizes a research study that compares chloride absorption in pre-conditioned concrete cubes with different concrete mixtures. Seventy-two concrete cubes were prepared with six different mixtures that varied slump, water-cement ratio, and compressive strength. Cubes were pre-conditioned to be dry, fully saturated, or partially saturated. Cubes were then exposed to a 10% sodium chloride solution for 160 days. Chloride absorption was analyzed at various time intervals. Results showed that chloride absorption varied depending on pre-conditioning, mixture properties, and exposure duration. Absorption increased over time and was higher in dry pre-conditioned cubes compared to saturated cubes. Impregnated cubes generally had lower absorption than
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Improvement on the concrete cracks by using Bacillus pastueriiijsrd.com
Cracks in concrete are irreversible and are one of the naturally weaknesses of concrete. Bacillus Pasteruii, a common soil bacterium induce the precipitation of calcite exhibited its positive potential in selectively consolidating simulated fractures in the consolidation of sand. A compression, flexural and durability tested on mortar cubes and concrete beams treated with bacteria were studied. The effect of different depth of crack on the compression, flexural and durability of concrete was studied. It was found that all the increase in depth of crack reduce the strength of cubes and beams.
Traditional Concrete Compositions to Cutting Edge Solutions..pptxSARANYA KANDASAMY
The transition from traditional concrete compositions to cutting-edge solutions represents a dynamic
evolution in the field of construction. This journey encompasses a spectrum of advancements, bridging
time-honored practices with innovative technologies to shape the built environment. From the basic mixture of cement, aggregates, and water to the integration of specialized additives, fibers, and nano materials, this progression signifies a pursuit of enhanced strength, durability, sustainability, and
functionality.At one end of the spectrum, traditional concrete compositions rely on well-established proportions of
components to create structures that have served humanity for centuries. This approach emphasizes the tried-and-true principles of concrete technology, providing stability and reliability in various applications.
IRJET- Internal Curing of Concrete using Pre Wetted Light Weight AggregatesIRJET Journal
The document summarizes a study on the use of pre-wetted lightweight aggregates for internal curing of concrete to improve its properties. It found that replacing 10% of coarse aggregates with expanded clay led to higher compressive strength, split tensile strength, and degree of hydration compared to normal concrete due to the water stored in the lightweight aggregates helping to cure the concrete from within. The optimum replacement was found to be 10% lightweight aggregate, beyond which strengths started decreasing. Internal curing produced a denser microstructure and reduced cracking compared to traditional external curing.
The document discusses materials used in reinforced concrete structures, including concrete, steel reinforcement, and their properties. It provides three key points:
1) Concrete quality is measured by strength and durability, which depend on water-cement ratio, aggregates, and hydration. Workability and economy are also important considerations in mix design.
2) Steel reinforcement commonly used includes deformed bars and welded wire fabric in various grades depending on the yield strength required.
3) The properties of both concrete and steel, such as stress-strain behavior, modulus of elasticity, creep, and shrinkage, influence the design and performance of reinforced concrete structures.
IRJET - Durability of Concrete with Differential Concrete Mix DesignIRJET Journal
The document discusses the durability of concrete with different concrete mix designs. It presents research on how water absorption, density, and sorptivity coefficient are affected by varying the water-cement ratio, slump, and compressive strength in concrete mixes. Seventy-two concrete cubes were prepared with six different mix designs - three mixes varied the slump and water-cement ratio at a constant compressive strength, while three other mixes varied the compressive strength and water-cement ratio at a constant slump. The cubes were tested to determine their rate of water absorption, density, and sorptivity coefficient at various time intervals over 28 days. The results showed that the sorptivity coefficient and rate of water absorption
This manuscript is about the concrete specification. The concrete specification testing is a process by which different tests are carried out such as compressive strength, carbonation depth, ASTM rapid chloride permeability, NDT chloride and initial surface absorption test (ISAT-10) to determine the quality and performance of the concrete in terms of strength, carbonation depth, chloride permeability and surface absorption.
Shrinkage Characterization of Cement Concrete with Various Supplementary Ceme...IRJET Journal
This document reviews the effects of supplementary cementitious materials (SCMs) and fibers on the shrinkage characteristics of concrete. It discusses the different types of shrinkage that can occur in concrete, including plastic, drying, and autogenous shrinkage. The use of SCMs like fly ash, slag, and silica fume are found to reduce shrinkage by replacing cement and participating in pozzolanic reactions. Fibers are also found to reduce shrinkage by providing a restraint against cracking. Super absorbent polymers can be used for internal curing to control shrinkage. Test methods for measuring shrinkage and other concrete properties are also outlined.
An Experimental Study on Rapid Chloride Penetration Test of Self Compacting C...ijtsrd
Self compacting concrete SCC is a very fluid concrete and a homogeneous mixture that solves most of the problems related to ordinary concrete. Self Compacting Concrete gets dense and compacted due to its own self weight. An experimental investigation has been carried out to determine different characters like filling ability, passing ability, segregation resistance workability and strength of Self Compacting Concrete SCC . And finally determining the chloride penetrability of SCC. Self Compacted Concrete is generally defined as the “Concrete, which does not need Compaction.†Due to these characteristics, SCC is ideally suited for concreting structures, which have heavily congested reinforcement or difficult access conditions. In this project, M40 grade concrete were made using European method. The compressive strength, split tension test obtained at the ages of 7, 14 and 28 days. Mr. R. Jeya Prakash | Ms. R. Nirmala ""An Experimental Study on Rapid Chloride Penetration Test of Self Compacting Concrete"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-3 , April 2019, URL: https://www.ijtsrd.com/papers/ijtsrd21650.pdf
Paper URL: https://www.ijtsrd.com/engineering/civil-engineering/21650/an-experimental-study-on-rapid-chloride-penetration-test-of-self-compacting-concrete/mr-r-jeya-prakash
1) The document discusses causes, prevention, and repair of concrete cracks. It identifies three main factors that cause cracks: internal and external stratification during concrete pouring, the transition zone between concrete and aggregate, and the multiphase porous system in cement.
2) Prevention methods discussed include controlling water-cement ratio, adding silica fume, and using high-quality aggregate.
3) Repair methods summarized are surface filling of small cracks, pressure grouting of larger cracks, and caulking of even larger cracks. The document concludes that structural defects during concrete pouring are the underlying cause of cracks.
On causes, prevention and repairing measures of concrete cracksIJERA Editor
At present, domestic and overseas researches on concrete cracks mainly focus on the formation of cracks from external factors, such as cracks caused by temperature, external loads and uneven settlement of foundation. Based on other scholars’ study on the reason and settlement of cracks, this paper starts from the defect of concrete structure, and proposes three factors affecting concrete cracks: internal and external stratification during the process of concrete placement, the presence of the transition zone of concrete and multiphase porous system of the cement. In addition, the author has summarized the prevention and repairing measures of cracks.
This document summarizes the key aspects of shotcrete, including its classification, materials, processes, specifications, and a case study on health and safety. Shotcrete is a sprayed concrete used for constructing curved surfaces like tunnels. It is conveyed through a hose and pneumatically projected. The case study examines efforts across various countries to reduce dust exposure for shotcrete workers, including improving shotcrete mixtures and equipment to reduce dust production and using personal protective equipment. Further research is still needed to improve worker health and safety.
Curing Methods and Their Effects on The Strength of ConcreteIJERA Editor
There are a lot of arguments on which method of curing concrete gives good strength. These different opinions results into this study, which aim at investigating the effects of different curing methods on the strength of concrete. Laboratory test was employed for this study. Normal concretes were prepared using specified mix ratio of 1:2:4 and 1:3:6. The cubes tested for compressive strength at 3, 7, 21, and 28 days of curing respectively using four curing methods namely immersion, sprinkling, polythene sheeting and sharp sand coating. Testing indicate that water immersion curing method as well as sprinkling (spraying ) methods of curing, provide better results than membrane (polythene sheeting) method of curing. While sharp sand gives least strength. The rate of drying was significant when the specimens were subjected to curing with polythene sheet method of curing. This thus hampered the hydration process and thus affected the compressive strength property of the hardened concrete. The overall findings of this study suggests that concrete should be cured by water immersion or spraying regularly to achieve a better compressive strength in concrete.
IRJET - Effectiveness of Concrete Ingredients on Isat in DCC CubesIRJET Journal
This document discusses a study that assessed the effectiveness of different concrete ingredients on initial surface absorption test (ISAT) values in dry conditioned concrete cubes. Six different concrete mixtures were prepared varying slump, water-cement ratio, and compressive strength. ISAT tests were conducted on 72 concrete cubes according to BS 1881 standards after drying for 3 days at 105±5°C. The results showed that ISAT values increased at initial testing for mixtures with lower compressive strength and water diffusion coefficient, and decreased with higher strength, constant slump, and over time. Higher water-cement ratios and slump also increased ISAT values. The study aimed to interpret the influence of drying conditions and mixture proportions on ISAT results.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
KHRI-Webinar(30-04-2020)-Shrinkage induced distress in concrete and remedies- Dr. Piyush Chausali(IITM) - Assistant Director KHRI.pdf
1. Webinar Series to Promote Quality Construction, Organized by KHRI
Shrinkage-Induced Distress in
Concrete and Remedies
Dr. Piyush Chaunsali
Assistant Professor, Department of Civil Engineering
IIT Madras, Chennai 600036
April 30, 2020
2. Webinar Series to Promote Quality Construction
Examples of Shrinkage Cracking
2
Concrete Society, UK
Cracks
3. Webinar Series to Promote Quality Construction
Examples of Shrinkage Cracking
3
Chaunsali et al., 2013
Cracks
Photo: Illinois DoT
4. Webinar Series to Promote Quality Construction
Volume Stability of Concrete
• What triggers the volume change in
concrete?
• Understand the link between stimulus
and response
4
Stimulus
Response
Shrinkage?
5. Webinar Series to Promote Quality Construction
Shrinkage of Concrete
• Stimulus: Change in moisture (external
drying, internal drying and chemical
reaction)
• Response: Change in length (volume)
5
Relative
Humidity
Shrinkage
6. Webinar Series to Promote Quality Construction
Shrinkage-Induced Cracking: Mechanics
6
Portland Cement Concrete
Fresh Concrete
Hardened
Concrete
T : Tension
Cracking
T
T
Stress due to Shrinkage
Stress Considering
Creep Relaxation
Tensile Strength
Stress
Age
Time of Cracking
No restraint
No cracking
Restraint
Cracking
7. Webinar Series to Promote Quality Construction
Influence of Relative Humidity on Shrinkage
• Ultimate shrinkage is greatly
influenced by relative humidity
• Lower relative humidity results
in higher shrinkage
7
Troxell et al., 1958
RH 50%
RH 70%
RH 100%
8. Webinar Series to Promote Quality Construction
Variation in Relative Humidity
8
City: Chennai
Duration: March 31 - April 28
City: New Delhi
Duration: March 31 - April 28
Relative
Humidity
9. Webinar Series to Promote Quality Construction
Volumetric Deformation
• Plastic shrinkage: Occurs in fresh Concrete while the concrete is still
plastic
• Autogenous shrinkage: Shrinkage without temperature change or
moisture loss (chemical and self-desiccation shrinkage during
hydration)
• Drying shrinkage: Generally considered in hardened concrete
• Thermal shrinkage: Due to temperature change
• Carbonation shrinkage: When hydrated cement paste reacts with CO2
9
10. Webinar Series to Promote Quality Construction 10
Shrinkage
hours days weeks months years
Time
Plastic
Thermal
(contraction)
Autogenous
Drying
Carbonation
Prof. Gettu
11. Webinar Series to Promote Quality Construction
Plastic Shrinkage Cracking
• Where? Random, Diagonal,
Over Reinforcement
• When? 30 mins – 6 hours
• Why? Higher evaporation
than bleeding
11
Concrete Society, UK, Technical Report No. 22
12. Webinar Series to Promote Quality Construction
Plastic Shrinkage Cracking
• Plastic shrinkage cracking occurs
when
bleeding rate < evaporation rate
• When the rate of evaporation
exceeds 1 kg/m2/hour, precautionary
measures are required to control
plastic shrinkage cracking
12
Bleeding Evaporation
Courtesy: Prof. Jason Weiss
13. Webinar Series to Promote Quality Construction
Estimation of Evaporation Rate
• The chart can be used to estimate
evaporation rate given the climatic conditions
• Based on the air temperature, relative
humidity, concrete temperature and wind
speed, evaporation rate at particular site can
be estimated
13
Hot Weather Concreting,J. ACI, Proc., Vol. 74, No. 8, p. 321, 1977
14. Webinar Series to Promote Quality Construction
Effect of Aggregate on Plastic Shrinkage
• Negative capillary pressure generated
due to the loss of moisture causes
plastic shrinkage
• Aggregates reduce the plastic shrinkage
14
Shrinkage
Strain
Drying Period
Concrete
Mortar
Paste
15. Webinar Series to Promote Quality Construction
Effect of Fibers on Reducing Plastic Shrinkage
Cracking
15
Sivakumar and Santhanam, 2007
Naaman et al., 2005
16. Webinar Series to Promote Quality Construction
Ways to Reduce Plastic Shrinkage Cracking
16
• Moisten aggregates
• Cool aggregates and mixing water
• Dampen subgrade
• Erect temporary windbreaks and sunshades
• Cover concrete
• Fog slab immediately after placing
• Curing compound
• Shrinkage reducing admixtures (SRAs)
• Add fibers
17. Webinar Series to Promote Quality Construction
Autogenous Shrinkage
• Autogenous shrinkage is significant in
low w/cm ratio (< 0.4) concrete mixtures
• Chemical shrinkage plus self-desiccation
➢Chemical shrinkage: characteristic of
cement hydration
➢Self-desiccation: internal drying of concrete
due to cement hydration (no moisture loss to
surroundings)
17
Courtesy: Prof. Jason Weiss
18. Webinar Series to Promote Quality Construction
Chemical Shrinkage: Measurement
• Observed by Le Chatelier over a century
ago
• Volume reduction associated with the
hydration reactions in a cementitious
material
• ASTM C1608
18
Courtesy: Prof. Jason Weiss
19. Webinar Series to Promote Quality Construction
Autogenous Shrinkage: Measurement
19
• Paste/mortar is encapsulated in a
corrugated tube, and the length change is
measured using digital dilatometer
• Measurement can be started immediately
after mixing
• ASTM C1698 Length-to-diameter 400:30 mm
20. Webinar Series to Promote Quality Construction
Early-Age Shrinkage in Cement Paste
20
Setting time
Jensen and Hansen, 2001
Courtesy: Prof. Jason Weiss
21. Webinar Series to Promote Quality Construction
Drying Shrinkage Cracking
21
Fresh Concrete
Hardened
Concrete
T : Tension
Cracking
T
T
Concrete Society, UK, Technical Report No. 22
22. Webinar Series to Promote Quality Construction
Drying Shrinkage Measurement
• Concrete prisms are used
to measure free shrinkage
following ASTM C157
22
Measured
Shrinkage
Drying Period
23. Webinar Series to Promote Quality Construction
Restrained Shrinkage Test
ASTM C1581
23
NI DAQ
Concrete Ring
Steel Ring
Computer
0 4 8 12 16 20 24 28
Age (days)
-100
-80
-60
-40
-20
0
20
Strain
in
Steel
Ring
()
Plain Concrete
Appearance of
Crack
According to ASTM C1581, the concrete mix exhibiting cracks beyond 28
days is expected to have low vulnerability to shrinkage cracking in the field.
24. Webinar Series to Promote Quality Construction
Drying Shrinkage: Influence of Specimen
Size
• Higher surface/volume ratio results in
higher rate of shrinkage
• Ultimate shrinkage values are similar
24
Shrinkage
Strain
Drying Period
4 inch cube
6 inch cube
25. Webinar Series to Promote Quality Construction
Influence of Aggregate Stiffness and Volume on
Shrinkage
25
n: 1.2 to 1.7
ACI Monograph, 1971 Troxell et al., 1958
𝜀𝑐𝑜𝑛𝑐𝑟𝑒𝑡𝑒 = 𝜀𝑝𝑎𝑠𝑡𝑒 1 − 𝑉𝑓𝑎𝑔𝑔
𝑛
• Increase in aggregate
volume or reduction in
paste volume results in
lower shrinkage
• Stiffer aggregates
exhibit lower shrinkage
Low modulus
High modulus
26. Webinar Series to Promote Quality Construction
Influence of Water Content
26
ACI 224R- 2008
For the same w/cm ratio, increase in water
content also results in higher drying shrinkage
due to increase in paste volume.
Concrete shrinkage increases with w/cm ratio for
given aggregate content. The effect is more
pronounced with lower aggregate contents.
27. Webinar Series to Promote Quality Construction
Influence of Drying and Wetting on Shrinkage
27
Mindess and Young, 1981
28. Webinar Series to Promote Quality Construction
Mechanism of Shrinkage
• Capillary stress (RH > 45 %)
• Disjoining pressure (RH > 45%)
➢Van der Waals forces attract adjacent particles
• Surface energy (RH < 45%)
➢Surface free energy increases as the most strongly adsorbed water is
removed
28
ln 𝑅𝐻 = −
2𝛾𝑉
𝑚
𝑟𝑅𝑇
𝜎𝐶𝑎𝑝 =
2𝛾
𝑟
29. Webinar Series to Promote Quality Construction
’s s
29
Relative vapor
pressure
H. Roper, 1966
I: Water lost from big pores
II: Water from smaller pores
III: Menisci break
IV: Interlayer
30. Webinar Series to Promote Quality Construction
Factors Affecting Shrinkage
• Mix Proportions
➢w/c (w/c εsh)
➢Paste/Aggregate (agg. vol. ε sh )
• Material Parameters
➢Aggregate stiffness
➢Mix composition (silica fume)
• Environmental Conditions
➢Curing conditions (R.H., temp, wind)
➢Age of drying (age ε sh )
➢Volume-to-surface area ratio (v/s ε sh )
30
31. Webinar Series to Promote Quality Construction
Other Shrinkage Mitigation Strategies
• Shrinkage reducing admixtures (SRAs)
• Expansive cements
• Light-weight aggregates (LWAs)
31
32. Webinar Series to Promote Quality Construction
Shrinkage Mitigation Using SRAs
SRAs reduce the surface tension of pore water, and hence the capillary stress is also reduced.
32
Restrained Shrinkage Test
Free Shrinkage Test
Control With SRA
Chaunsali et al., 2013
33. Webinar Series to Promote Quality Construction
Shrinkage Mitigation Using Expansive
Cements
• Examples: Type K, Type M, Type S
and Type G cements (ACI 223)
33
0 20 40 60 80 100 120
Age (days)
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
Deformation
(
)
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
Deformation
(
)
Control
Type K
Type G
Expansion
Shrinkage
Start of Drying (7d)
Fresh Concrete
Hardened
Concrete
Tensile stresses due to shrinkage
C C
C C
T T
Chaunsali et al., 2013
34. Webinar Series to Promote Quality Construction
Application of Type K Cement for Preventing
Shrinkage Cracking
34
Transverse
Crack
No cracks
CSA Concrete Deck
OPC Concrete Deck
Photo: Illinois DoT
35. Webinar Series to Promote Quality Construction
Shrinkage Mitigation Using LWAs
35
Henkensiefken et al., 2009
Castro et al., 2010
Delay in cracking
36. Webinar Series to Promote Quality Construction
Thermal Shrinkage
• Thermal shrinkage is of great importance in massive concrete
structures
• Factors affecting thermal shrinkage
➢Degree of restraint
➢Temperature change
➢Coefficient of thermal expansion of aggregates
➢Cement type and fineness
36
37. Webinar Series to Promote Quality Construction
Carbonation Shrinkage
• Surface zone of concrete undergoes shrinkage
due to the carbonation of the hydrated cement
paste.
• Carbonation shrinkage is probably caused by
the dissolving of the Ca(OH)2 crystals and the
depositing of CaCO3 in spaces free from stress.
• Carbonation increases the shrinkage at
intermediate relative humidity.
➢At low humidity, there is insufficient water in the pores
to form carbonic acid with the CO2.
➢On the other hand, when the pores are saturated, the
diffusion of CO2 is slow.
37
G. Verbeck, 1958
38. Webinar Series to Promote Quality Construction
Contraction Joints
38
D
D
Portland Cement Association
Courtesy: Prof. Jason Weiss
39. Webinar Series to Promote Quality Construction
Main Takeaways
• Plastic shrinkage cracking: Efforts must be directed to reduce evaporation rate
• Importance of aggregate volume, aggregate stiffness, w/cm ratio and surface-
to-volume ratio of concrete element in influencing shrinkage of concrete
• SRAs, fibers, expansive cements and LWAs can be used to mitigate shrinkage-
induced cracking
• Autogenous shrinkage is significant in low w/cm ratio mixtures
• Thermal shrinkage is greatly influenced by adiabatic temperature rise and is
prominent in thick concrete elements
39