The presentation about the historical background about the history of admixtures used in concrete that is helpful for doing assignments on concrete technology subject for civil engineering students
This document discusses high-strength concrete (HSC). It defines HSC as concrete with a 28-day compressive strength of over 40 MPa. HSC uses a low water-cement ratio, smaller aggregate sizes, and admixtures like silica fume and superplasticizers. Compared to normal-strength concrete, HSC has higher resistance to pressure, modulus of elasticity, and strength gained at an earlier age. Some applications of HSC mentioned include bridges, high-rise buildings, power plants, and skyscrapers. The document concludes that interest in HSC is growing rapidly due to its advantages like reduced material needs and increased construction speeds.
Deterioration of concrete structures can occur through various chemical, physical, and mechanical processes over time. Scaling and disintegration are forms of physical deterioration where the concrete's surface layers break down from freezing and thawing or weathering. Corrosion of reinforcement rebar can develop due to penetration of chloride ions or carbonation reducing the pH. Other causes include sulfate attack, alkali-aggregate reactions, abrasion, high temperatures, and erosion. Proper mix design and concrete quality can increase durability and prevent deterioration.
This document discusses self-curing concrete as an alternative to traditional water curing methods. Self-curing concrete contains chemical compounds that restrict the mixing water from leaving the curing concrete, allowing hydration to continue. This eliminates the need for external water curing in remote areas or projects where water access is limited. Self-curing concrete provides benefits like higher strength, durability, and resistance to cracking compared to uncured concrete through its internal curing mechanism. It is a useful technique when traditional water curing is not feasible or economical.
Admixtures are added in concrete to improve the quality of concrete.
Fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), Metakaolin (MK), and rice husk ash (RHA)
Possess certain characteristics through which they influence the properties of concrete differently.
Effect of mineral admixtures on the properties of fresh concrete is very important as these properties may affect the durability and mechanical properties of concrete.
This document discusses polymers used for concrete repair. It describes two main types of polymers: those used to modify cementitious systems and thermosetting resin systems like epoxy, polyester, and acrylic. Polymer latexes are used as admixtures in cementitious systems where they improve properties like strength, permeability, and bonding. Resin repair mortars are used for smaller repairs under 12mm and rely on impermeability for steel protection. Epoxy, polyester, and acrylic resins are discussed in more detail regarding their chemical curing processes and appropriate uses in concrete repair.
Here, I attach a PowerPoint presentation created by me for a competition held by UltraTech. Have a look at this and feel free to share your views with me.
CTEP - UNIT - I - ADMIXTURES & CONSTRUCTION CHEMICALSShankar Ramasamy
This document provides information on concrete admixtures, including definitions and uses. It discusses different types of admixtures such as air-entraining agents, water reducers, plasticizers, superplasticizers, retarders, accelerators, and damp proofing admixtures. For each type of admixture, the document outlines their properties, mechanisms, advantages, and applications in concrete mixing and construction. In addition, the document covers curing compounds and polymer bonding agents used for curing concrete and bonding new concrete to existing structures.
This document summarizes a student project investigating the use of fly ash and alccofine in pervious concrete for pavement applications. A group of 8 students conducted experiments with different mix designs containing fly ash and alccofine at various percentages as partial replacements for cement. The project aimed to examine properties like compressive strength, void ratio, and infiltration rate. Test results were analyzed to determine the optimal mix for pavement usage considering strength and permeability. The findings of this study could help promote the utilization of industrial wastes in pervious concrete construction.
This document discusses high-strength concrete (HSC). It defines HSC as concrete with a 28-day compressive strength of over 40 MPa. HSC uses a low water-cement ratio, smaller aggregate sizes, and admixtures like silica fume and superplasticizers. Compared to normal-strength concrete, HSC has higher resistance to pressure, modulus of elasticity, and strength gained at an earlier age. Some applications of HSC mentioned include bridges, high-rise buildings, power plants, and skyscrapers. The document concludes that interest in HSC is growing rapidly due to its advantages like reduced material needs and increased construction speeds.
Deterioration of concrete structures can occur through various chemical, physical, and mechanical processes over time. Scaling and disintegration are forms of physical deterioration where the concrete's surface layers break down from freezing and thawing or weathering. Corrosion of reinforcement rebar can develop due to penetration of chloride ions or carbonation reducing the pH. Other causes include sulfate attack, alkali-aggregate reactions, abrasion, high temperatures, and erosion. Proper mix design and concrete quality can increase durability and prevent deterioration.
This document discusses self-curing concrete as an alternative to traditional water curing methods. Self-curing concrete contains chemical compounds that restrict the mixing water from leaving the curing concrete, allowing hydration to continue. This eliminates the need for external water curing in remote areas or projects where water access is limited. Self-curing concrete provides benefits like higher strength, durability, and resistance to cracking compared to uncured concrete through its internal curing mechanism. It is a useful technique when traditional water curing is not feasible or economical.
Admixtures are added in concrete to improve the quality of concrete.
Fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), Metakaolin (MK), and rice husk ash (RHA)
Possess certain characteristics through which they influence the properties of concrete differently.
Effect of mineral admixtures on the properties of fresh concrete is very important as these properties may affect the durability and mechanical properties of concrete.
This document discusses polymers used for concrete repair. It describes two main types of polymers: those used to modify cementitious systems and thermosetting resin systems like epoxy, polyester, and acrylic. Polymer latexes are used as admixtures in cementitious systems where they improve properties like strength, permeability, and bonding. Resin repair mortars are used for smaller repairs under 12mm and rely on impermeability for steel protection. Epoxy, polyester, and acrylic resins are discussed in more detail regarding their chemical curing processes and appropriate uses in concrete repair.
Here, I attach a PowerPoint presentation created by me for a competition held by UltraTech. Have a look at this and feel free to share your views with me.
CTEP - UNIT - I - ADMIXTURES & CONSTRUCTION CHEMICALSShankar Ramasamy
This document provides information on concrete admixtures, including definitions and uses. It discusses different types of admixtures such as air-entraining agents, water reducers, plasticizers, superplasticizers, retarders, accelerators, and damp proofing admixtures. For each type of admixture, the document outlines their properties, mechanisms, advantages, and applications in concrete mixing and construction. In addition, the document covers curing compounds and polymer bonding agents used for curing concrete and bonding new concrete to existing structures.
This document summarizes a student project investigating the use of fly ash and alccofine in pervious concrete for pavement applications. A group of 8 students conducted experiments with different mix designs containing fly ash and alccofine at various percentages as partial replacements for cement. The project aimed to examine properties like compressive strength, void ratio, and infiltration rate. Test results were analyzed to determine the optimal mix for pavement usage considering strength and permeability. The findings of this study could help promote the utilization of industrial wastes in pervious concrete construction.
Distress of concrete structures & their repair techniquesZaid Ansari
This document discusses concrete distress and repair techniques. It begins by explaining that concrete structures may need repair after 25-30 years of service without maintenance. It then lists common causes of concrete distress like weathering, environmental effects, poor design/construction, and water leakage leading to corrosion. The document outlines expected service lives for different structure types. It also describes common concrete failure modes and causes of early deterioration. The remainder of the document discusses techniques for identifying distressed concrete, various repair materials and methods, and the need for trained concrete workers.
This document presents a project on the properties and applications of foam concrete. It was presented by two students from the Department of Civil Engineering at KUET. The document defines foam concrete as a cement-based slurry with at least 20% entrained foam. It discusses the materials and manufacturing process of foam concrete and describes its key properties like compressive strength, thermal conductivity, drying shrinkage and fire resistance which vary according to density. The document also outlines various applications of foam concrete in construction based on density and highlights its advantages like light weight and rapid construction as well as limitations. Finally, it discusses the potential of foam concrete in Bangladesh.
you would be aware about the different types of special concrete being used in india.All these types of concrete are being produced by ultratech concrete, for more details visit www.ultratechconcrete.com/concrete_types.html
Sustainable concrete uses less energy and produces fewer carbon emissions than regular concrete. It incorporates waste and recycled materials like fly ash and slag to replace portions of cement. Using these supplementary cementitious materials can increase sustainability by reducing embodied energy and carbon in the concrete. Sustainable strategies also include minimizing water use, using local and recycled aggregates, and designing for durability to lessen environmental impacts over the concrete's lifetime. The presentation outlined various approaches to sustainable concrete and its advantages in promoting greener construction.
Self-healing concrete contains special bacteria and a chemical precursor that allow it to autonomously repair cracks. When cracks form, water activates the precursor which induces bacteria to fill the cracks with limestone, healing them. This increases the concrete's durability and service life. The bacteria, like Pseudofirmus and Cohnii, must withstand the alkaline environment. Calcium lactate is a commonly used precursor that the bacteria metabolize to precipitate limestone. This technology could enable more durable infrastructure with reduced maintenance needs.
This document discusses curing of concrete, which involves maintaining moisture content and temperature to allow desired properties to develop. Proper curing increases strength, durability, and resistance to damage. It describes the hydration process where water reacts with cement compounds. A minimum of 38% water by weight of cement is needed for full hydration. Self-curing concrete uses chemicals to retain mixing water and prevent drying. Membrane-forming compounds form films on concrete surfaces that reduce evaporation and allow curing without applied water. Different types of compounds and their application procedures are outlined.
1. The document discusses various types of special concretes including lightweight concrete, foam concrete, self-compacting concrete, vacuum concrete, fibre reinforced concrete, ferrocement, ready mix concrete, slurry infiltrated fibre concrete (SIFCON), and shotcrete.
2. Lightweight concrete uses lightweight aggregates like shale, clay, or slate to reduce density while maintaining strength. Foam concrete is made by injecting air or gas into the mix to create a cellular structure.
3. Self-compacting concrete can be placed without vibration due to its fluidity. Vacuum concrete has water removed using vacuum mats to increase strength.
Fiber reinforced concrete is a composite material made of cement, mortar or concrete with closely spaced fibers added. The fibers, which can include glass, carbon, polypropylene or nylon, increase the tensile strength and crack resistance of the concrete.
Fiberglass reinforced concrete (GFRC) specifically uses glass fibers in the mix. It provides an ultra-strong yet flexible concrete that protects against environmental damage. GFRC is lightweight, durable, and can be cast into complex shapes.
Some key properties and applications of fiber reinforced concrete include increased tensile strength, impact resistance, limited crack growth, use in pavement overlays, industrial floors, bridges, canal linings, blast resistant structures, and pre
Self-compacting concrete (SCC) is a highly flowable concrete that can spread and consolidate under its own weight without vibration or compaction. Researchers at the University of Tokyo developed SCC in the late 1980s to address labor shortages. By the early 1990s, Japan was using SCC without vibration, and its use spread to other countries. SCC offers benefits like reduced labor costs, faster construction, and improved safety and finishes. It requires special mix designs using superplasticizers, viscosity agents, and mineral admixtures to achieve flowability, passing ability through reinforcement, and resistance to segregation.
Admixtures are materials added to concrete mixes to modify properties. There are two main types - chemical and mineral. Chemical admixtures include plasticizers, superplasticizers, retarders, accelerators, and air-entraining agents. Mineral admixtures include fly ash, slag, and silica fume. Admixtures are used to increase workability, strength, and durability while decreasing water demand and permeability. Common admixtures like plasticizers and superplasticizers work by dispersing cement particles and lubricating the mix to increase flowability.
The document discusses various types of chemical admixtures used for concrete, including plasticizers, superplasticizers, retarders, accelerators, and air-entraining admixtures. It explains that admixtures can modify the properties of fresh and hardened concrete by altering workability, strength development, permeability, and durability. Superplasticizers in particular are highlighted as they can significantly reduce water content and increase workability and strength. The document concludes that superplasticizers and air-entraining admixtures are most commonly used, and that superplasticizers allow for reduced cement and increased construction of large structures.
It is special type of concrete that can take the bending stresses.
It consist of special type of materials that makes it flexible. It was developed by the Professor Victor Li at the University of Michigan.
Its engineering name is Engineered Cementitious Composite (ECC).
It exhibits the property of a ductile material instead of a brittle material which is shown by the conventional concrete.
This material can bring the revolution because of its some special quality such as flexibility, self-healing, lighter weight, etc. In some countries such as Japan, Korea, U.S.A, etc the flexible concrete is used in many structure.
But in India it is still a new material and requires proper research for its use in India.
Soon we may saw the use of flexible concrete in many structure.
For more info Visit this link: http://civildigital.com/all-about-flexible-concrete-bendable-concrete-engineered-cementitious-composite-ecc/
Image Courtesy:
https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2016/1-newbendablec.jpg
This document discusses concrete permeability and durability. It defines concrete and its composition, noting that concrete is made up of cement paste and aggregates. The cement paste binds the aggregates but is also porous, allowing water and chemicals to pass through. Several degradation mechanisms are described, all of which involve the penetration of water or other substances into the concrete. The document emphasizes that permeability determines a concrete's vulnerability, and that reducing permeability is key to improving durability. It describes different transport mechanisms by which substances can move through concrete, including diffusion, capillary action, and permeation.
The document discusses bendable or engineered cementitious composite (ECC) concrete. It is a type of fiber-reinforced concrete that is ductile and crack-resistant. ECC concrete uses microfibers, a slick coating on the fibers, fine sand, and superplasticizers. It bends like metal and is stronger and more durable than regular concrete. Structures made of ECC concrete are earthquake and crack resistant. Examples of uses include earthquake-proof buildings, flexible concrete canvases for military use, and more durable bridges and roads.
This document discusses various types of admixtures used in concrete, including their functions, compositions, and advantages. It defines admixtures as materials other than water, aggregates, cement, and fiber that are added to concrete mixtures to modify properties. The main types of admixtures discussed are air-entraining, water-reducing, superplasticizers, and set-retarding admixtures. Air-entrainers introduce tiny air bubbles that increase durability. Water-reducers and superplasticizers increase workability without increasing water content. Set-retarders delay the initial setting of concrete. The document provides details on the chemical compositions and functioning of different admixture types.
Formation of cracks in concrete is a common phenomenon that allows many chemicals, water to seep inside leading to decrease in durability, including progressive drop in concrete strength. The maintenance and repair of structural concrete is very complex phenomenon. Self-healing concrete, using bacteria at the time of mixing, is an impressive solution to overcome these kinds of adverse effects. It is an economical way is to prepare concrete of better quality. The study was carried out to investigate the concrete performance by adding bacteria “Bacillus subtilis”. This Self-Healing concrete is also known as as Bio-concrete. Bacteria was induced directly in the concrete mix along with calcium lactate i.e., an organic precursor producing calcium carbonate crystals that block cracks and pores in the concrete. Samples were made with different quantities of bacteria and results showed significant increase in compressive strength of concrete and decrease in permeability. The concrete micro-structure was observed under SEM which also confirmed the experimental results obtained.
Pervious or porous concrete is a special type of concrete with a high porosity that allows water to pass directly through it. This is achieved through a mix with a highly interconnected void content of around 20-35% and the absence of fine aggregates. Pervious concrete has environmental benefits like reducing stormwater runoff and replenishing groundwater, but also has disadvantages like being susceptible to clogging. It has a range of applications in pavements, sports courts, and other surfaces. Proper mix design, placement, finishing, curing and maintenance are important to ensure the permeability and strength of pervious concrete.
Self-compacting concrete (SCC) is a highly fluid concrete that can flow and consolidate under its own weight without vibration. It was developed in Japan in the 1980s in response to a shortage of skilled labor. SCC mixtures have more powder and less coarse aggregate than conventional concrete, and include high-range water reducers and viscosity modifying agents. SCC allows for easier placement, improved surface finish, and greater design freedom.
This document provides information about ready-mix concrete from an educational presentation. It introduces the topic and defines ready-mix concrete. It then discusses the main ingredients of concrete - cement, sand, coarse aggregate, water and admixtures - describing each in more detail. The document also covers the manufacturing process of ready-mix concrete, advantages, status and challenges in India, as well as some common quality problems and their causes.
Distress of concrete structures & their repair techniquesZaid Ansari
This document discusses concrete distress and repair techniques. It begins by explaining that concrete structures may need repair after 25-30 years of service without maintenance. It then lists common causes of concrete distress like weathering, environmental effects, poor design/construction, and water leakage leading to corrosion. The document outlines expected service lives for different structure types. It also describes common concrete failure modes and causes of early deterioration. The remainder of the document discusses techniques for identifying distressed concrete, various repair materials and methods, and the need for trained concrete workers.
This document presents a project on the properties and applications of foam concrete. It was presented by two students from the Department of Civil Engineering at KUET. The document defines foam concrete as a cement-based slurry with at least 20% entrained foam. It discusses the materials and manufacturing process of foam concrete and describes its key properties like compressive strength, thermal conductivity, drying shrinkage and fire resistance which vary according to density. The document also outlines various applications of foam concrete in construction based on density and highlights its advantages like light weight and rapid construction as well as limitations. Finally, it discusses the potential of foam concrete in Bangladesh.
you would be aware about the different types of special concrete being used in india.All these types of concrete are being produced by ultratech concrete, for more details visit www.ultratechconcrete.com/concrete_types.html
Sustainable concrete uses less energy and produces fewer carbon emissions than regular concrete. It incorporates waste and recycled materials like fly ash and slag to replace portions of cement. Using these supplementary cementitious materials can increase sustainability by reducing embodied energy and carbon in the concrete. Sustainable strategies also include minimizing water use, using local and recycled aggregates, and designing for durability to lessen environmental impacts over the concrete's lifetime. The presentation outlined various approaches to sustainable concrete and its advantages in promoting greener construction.
Self-healing concrete contains special bacteria and a chemical precursor that allow it to autonomously repair cracks. When cracks form, water activates the precursor which induces bacteria to fill the cracks with limestone, healing them. This increases the concrete's durability and service life. The bacteria, like Pseudofirmus and Cohnii, must withstand the alkaline environment. Calcium lactate is a commonly used precursor that the bacteria metabolize to precipitate limestone. This technology could enable more durable infrastructure with reduced maintenance needs.
This document discusses curing of concrete, which involves maintaining moisture content and temperature to allow desired properties to develop. Proper curing increases strength, durability, and resistance to damage. It describes the hydration process where water reacts with cement compounds. A minimum of 38% water by weight of cement is needed for full hydration. Self-curing concrete uses chemicals to retain mixing water and prevent drying. Membrane-forming compounds form films on concrete surfaces that reduce evaporation and allow curing without applied water. Different types of compounds and their application procedures are outlined.
1. The document discusses various types of special concretes including lightweight concrete, foam concrete, self-compacting concrete, vacuum concrete, fibre reinforced concrete, ferrocement, ready mix concrete, slurry infiltrated fibre concrete (SIFCON), and shotcrete.
2. Lightweight concrete uses lightweight aggregates like shale, clay, or slate to reduce density while maintaining strength. Foam concrete is made by injecting air or gas into the mix to create a cellular structure.
3. Self-compacting concrete can be placed without vibration due to its fluidity. Vacuum concrete has water removed using vacuum mats to increase strength.
Fiber reinforced concrete is a composite material made of cement, mortar or concrete with closely spaced fibers added. The fibers, which can include glass, carbon, polypropylene or nylon, increase the tensile strength and crack resistance of the concrete.
Fiberglass reinforced concrete (GFRC) specifically uses glass fibers in the mix. It provides an ultra-strong yet flexible concrete that protects against environmental damage. GFRC is lightweight, durable, and can be cast into complex shapes.
Some key properties and applications of fiber reinforced concrete include increased tensile strength, impact resistance, limited crack growth, use in pavement overlays, industrial floors, bridges, canal linings, blast resistant structures, and pre
Self-compacting concrete (SCC) is a highly flowable concrete that can spread and consolidate under its own weight without vibration or compaction. Researchers at the University of Tokyo developed SCC in the late 1980s to address labor shortages. By the early 1990s, Japan was using SCC without vibration, and its use spread to other countries. SCC offers benefits like reduced labor costs, faster construction, and improved safety and finishes. It requires special mix designs using superplasticizers, viscosity agents, and mineral admixtures to achieve flowability, passing ability through reinforcement, and resistance to segregation.
Admixtures are materials added to concrete mixes to modify properties. There are two main types - chemical and mineral. Chemical admixtures include plasticizers, superplasticizers, retarders, accelerators, and air-entraining agents. Mineral admixtures include fly ash, slag, and silica fume. Admixtures are used to increase workability, strength, and durability while decreasing water demand and permeability. Common admixtures like plasticizers and superplasticizers work by dispersing cement particles and lubricating the mix to increase flowability.
The document discusses various types of chemical admixtures used for concrete, including plasticizers, superplasticizers, retarders, accelerators, and air-entraining admixtures. It explains that admixtures can modify the properties of fresh and hardened concrete by altering workability, strength development, permeability, and durability. Superplasticizers in particular are highlighted as they can significantly reduce water content and increase workability and strength. The document concludes that superplasticizers and air-entraining admixtures are most commonly used, and that superplasticizers allow for reduced cement and increased construction of large structures.
It is special type of concrete that can take the bending stresses.
It consist of special type of materials that makes it flexible. It was developed by the Professor Victor Li at the University of Michigan.
Its engineering name is Engineered Cementitious Composite (ECC).
It exhibits the property of a ductile material instead of a brittle material which is shown by the conventional concrete.
This material can bring the revolution because of its some special quality such as flexibility, self-healing, lighter weight, etc. In some countries such as Japan, Korea, U.S.A, etc the flexible concrete is used in many structure.
But in India it is still a new material and requires proper research for its use in India.
Soon we may saw the use of flexible concrete in many structure.
For more info Visit this link: http://civildigital.com/all-about-flexible-concrete-bendable-concrete-engineered-cementitious-composite-ecc/
Image Courtesy:
https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2016/1-newbendablec.jpg
This document discusses concrete permeability and durability. It defines concrete and its composition, noting that concrete is made up of cement paste and aggregates. The cement paste binds the aggregates but is also porous, allowing water and chemicals to pass through. Several degradation mechanisms are described, all of which involve the penetration of water or other substances into the concrete. The document emphasizes that permeability determines a concrete's vulnerability, and that reducing permeability is key to improving durability. It describes different transport mechanisms by which substances can move through concrete, including diffusion, capillary action, and permeation.
The document discusses bendable or engineered cementitious composite (ECC) concrete. It is a type of fiber-reinforced concrete that is ductile and crack-resistant. ECC concrete uses microfibers, a slick coating on the fibers, fine sand, and superplasticizers. It bends like metal and is stronger and more durable than regular concrete. Structures made of ECC concrete are earthquake and crack resistant. Examples of uses include earthquake-proof buildings, flexible concrete canvases for military use, and more durable bridges and roads.
This document discusses various types of admixtures used in concrete, including their functions, compositions, and advantages. It defines admixtures as materials other than water, aggregates, cement, and fiber that are added to concrete mixtures to modify properties. The main types of admixtures discussed are air-entraining, water-reducing, superplasticizers, and set-retarding admixtures. Air-entrainers introduce tiny air bubbles that increase durability. Water-reducers and superplasticizers increase workability without increasing water content. Set-retarders delay the initial setting of concrete. The document provides details on the chemical compositions and functioning of different admixture types.
Formation of cracks in concrete is a common phenomenon that allows many chemicals, water to seep inside leading to decrease in durability, including progressive drop in concrete strength. The maintenance and repair of structural concrete is very complex phenomenon. Self-healing concrete, using bacteria at the time of mixing, is an impressive solution to overcome these kinds of adverse effects. It is an economical way is to prepare concrete of better quality. The study was carried out to investigate the concrete performance by adding bacteria “Bacillus subtilis”. This Self-Healing concrete is also known as as Bio-concrete. Bacteria was induced directly in the concrete mix along with calcium lactate i.e., an organic precursor producing calcium carbonate crystals that block cracks and pores in the concrete. Samples were made with different quantities of bacteria and results showed significant increase in compressive strength of concrete and decrease in permeability. The concrete micro-structure was observed under SEM which also confirmed the experimental results obtained.
Pervious or porous concrete is a special type of concrete with a high porosity that allows water to pass directly through it. This is achieved through a mix with a highly interconnected void content of around 20-35% and the absence of fine aggregates. Pervious concrete has environmental benefits like reducing stormwater runoff and replenishing groundwater, but also has disadvantages like being susceptible to clogging. It has a range of applications in pavements, sports courts, and other surfaces. Proper mix design, placement, finishing, curing and maintenance are important to ensure the permeability and strength of pervious concrete.
Self-compacting concrete (SCC) is a highly fluid concrete that can flow and consolidate under its own weight without vibration. It was developed in Japan in the 1980s in response to a shortage of skilled labor. SCC mixtures have more powder and less coarse aggregate than conventional concrete, and include high-range water reducers and viscosity modifying agents. SCC allows for easier placement, improved surface finish, and greater design freedom.
This document provides information about ready-mix concrete from an educational presentation. It introduces the topic and defines ready-mix concrete. It then discusses the main ingredients of concrete - cement, sand, coarse aggregate, water and admixtures - describing each in more detail. The document also covers the manufacturing process of ready-mix concrete, advantages, status and challenges in India, as well as some common quality problems and their causes.
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%.
Admixtures are added to concrete mixes to improve performance properties. Common types include plasticizers, superplasticizers, retarders, accelerators, and air-entraining admixtures. They allow reductions in water content or increases in workability. Trial mixes should be done to determine appropriate dosage for a given mix, as effect depends on cement and aggregates used. Admixtures improve qualities like strength, permeability, bleeding resistance, and durability in freezing environments.
Self-compacting concrete (SCC) was developed in Japan in the 1980s to achieve complete compaction without vibration. SCC flows under its own weight, fills formwork and passes through reinforced areas without segregation of ingredients. It consists of cement, fine and coarse aggregates, chemical and mineral admixtures. Superplasticizers and viscosity modifying agents provide workability and stability. Tests like slump flow, V-funnel, and J-ring evaluate filling ability, passing ability and resistance to segregation. SCC offers benefits of reduced labor, better compaction and surface finish compared to conventional concrete but requires more precise material proportions and quality control.
Seminar on Self Compacting Concrete SCC (special concrete)sreestr18
This document discusses self-compacting concrete (SCC), which is a highly fluid concrete that can consolidate under its own weight without vibration. SCC was developed in Japan in the 1980s to create durable concrete structures independent of construction workers' skill levels. The document outlines the key components of SCC including cement, aggregates, water, and chemical admixtures. It also describes various tests used to evaluate the filling ability, passing ability, and segregation resistance of SCC, such as slump flow, L-box, and V-funnel tests. The benefits and challenges of using SCC are noted. Examples of large infrastructure projects utilizing SCC include bridges and the Delhi metro system.
Admixture of concrete power point presentationARUNKUMARC39
Chemical admixtures and mineral additives are used in concrete construction to improve properties and performance. Common admixtures include plasticizers, superplasticizers, retarders, accelerators, and air-entraining agents. Mineral additives like fly ash, silica fume, and blast furnace slag are pozzolanic and can enhance strength and durability while also reducing costs. These admixtures and additives allow concrete to be placed more easily, provide targeted properties, and improve quality under difficult conditions.
The document discusses self-compacting concrete (SCC), which is a special type of concrete that can be cast without compaction or vibration due to its high resistance to segregation. SCC was first developed in Japan in 1988 in response to problems with concrete durability and labor shortages. SCC achieves self-compacting behavior through adjustments to the aggregate content and use of chemical and mineral admixtures. Tests are used to evaluate properties like flowability, passing ability, and segregation resistance. Benefits of SCC include reduced labor costs, faster placement, improved surface finish, and better consolidation around reinforcement.
IRJET- Use of Brick Dust and Fly Ash as a Replacement of Fine Aggregates in S...IRJET Journal
This document discusses a study on the use of brick dust and fly ash as replacements for fine aggregates in self-compacting concrete. It provides background on self-compacting concrete and its advantages over normal vibrated concrete. The study aims to compare the mechanical properties of self-compacting concrete and normal concrete with various ratios of fly ash and brick dust replacing fine aggregate. A literature review covers research on the effects of paste content and powder-to-water ratio on the properties of self-compacting concrete, as well as using fly ash and brick dust as additions in concrete mixes.
This document provides an overview of self-compacting concrete (SCC). It begins by defining SCC as a concrete that can be placed and consolidated without vibration. The document then discusses the benefits of SCC, including improved quality, faster construction, and better health and safety. It provides details on the development of SCC in Japan in the 1980s and the three main types. The document outlines the key properties SCC must have to achieve self-compaction and discusses applications. It also summarizes several literature reviews on the mix design, mechanical properties, and use of fly ash in SCC. In conclusion, the document introduces the methodology and outline used in the project to study SCC.
This document provides information on self-compacting concrete (SCC) and light-weight concrete. It defines SCC as concrete that can flow and fill formwork without vibration due to its high fluidity. Benefits of SCC include faster construction, improved quality, and a safer work environment. Light-weight concrete is defined as having a density of less than 2200kg/m3, containing porous aggregates, and including an expanding agent. Examples of structures built with SCC include Burj Dubai and an airport control tower in Stockholm. Requirements for producing SCC and light-weight concrete are also outlined.
Use of chemical admixtures and mineral additives in various kinds of high performance and high strength concrete is essential. I have explained how it works.
This document discusses self-compacting concrete (SCC), which does not require vibration for compaction. It can be designed to have good filling ability, passing ability, and segregation resistance. The document outlines the objectives, specifications, advantages, applications, characteristics, and test methods for SCC. It also reviews literature on using fibers or fly ash to improve properties of hardened SCC and its alkaline resistance.
This document provides an overview of non-film forming concrete sealers, including penetrating silane sealers, crack healer-sealers like MMA and epoxy, and their applications. It discusses how sealers prevent water and chemical intrusion into concrete to extend its life. Sealers are presented as a cost-effective solution compared to deck reconstruction. Application features, efficiency, specifications and tests are reviewed to demonstrate sealer technologies and recommend standardized regional specifications.
high performance concrete by ABHINAV RAWATAbhinav Rawat
High performance concrete (HPC) provides improved strength, durability, workability, and toughness compared to normal concrete. HPC achieves these properties through the use of high-quality cement, supplementary cementitious materials like fly ash and silica fume, and superplasticizers. The main purpose of HPC is to enhance the life of structures by improving impermeability and durability. HPC requires sufficient workability despite very low water-cement ratios, attained through superplasticizers. Strength ranges from 60 to 150 MPa, while improved elastic modulus and dimensional stability counteract undesirable volume changes.
This document discusses high performance concrete (HPC) and ultra-high performance concrete (UHPC), including their mix designs, ingredients, characteristics, advantages, disadvantages, applications, and specific structures where HPC has been used. HPC is designed to achieve higher strength, durability, and workability than conventional concrete through the use of additives like fly ash, slag, and superplasticizers. It has been used in tunnels, bridges, tall buildings, and other structures where high strength and durability are required.
Chemical admixtures are added to concrete mixes to modify properties like workability, setting time, strength, and durability. There are five main types of admixtures: retarders which slow setting; accelerators which speed setting; superplasticizers which increase workability; water reducers which decrease water needs; and air-entrainers which introduce tiny air bubbles that improve freeze-thaw resistance. Producers use admixtures to reduce costs, modify hardened concrete properties, and ensure quality during mixing and placement.
This document provides an introduction to self-consolidating concrete (SCC), including its origins in Japan in the 1980s, its key properties of low yield stress and high viscosity, and factors for successful mixes. SCC flows easily but remains homogeneous, eliminating the need for vibration. It enables productivity gains but requires careful quality control. While more expensive initially than conventional concrete, SCC provides economic benefits through reduced labor and improved aesthetics and safety.
This document provides information on various types of admixtures used in concrete. It discusses mineral admixtures including slag, pozzolanas and fillers. It describes different chemical admixtures such as accelerators, retarders, air entraining agents, water reducers, plasticizers, and super plasticizers. Specific admixtures like fly ash, GGBS, and silica fume are explained in detail along with their effects on fresh and hardened concrete. High volume fly ash concrete and its properties are also summarized.
this presentation deals with the different types of cracks generated in concrete during its usage and after its application and also methods to retrofit these cracks
the main component of civil engineering is concrete and this presentation is based on the different types of concrete used in civil engineering that will help students
The document outlines the 8 steps for achieving a concrete mix design: 1) choosing slump, 2) choosing aggregate size, 3) estimating water and air content, 4) selecting water-cement ratio, 5) calculating cement content, 6) estimating aggregate content, 7) estimating fine aggregate content, and 8) conducting a laboratory trial batch. It then provides an example of designing a mix for a volume of 1.54 m3 using a ratio of 1:2:4 for cement, fine aggregate, and coarse aggregate respectively.
Paints are used to protect surfaces from weathering and corrosion and improve appearance. They are composed of a base, vehicle, pigment, thinner, and dryers. The base forms the main paint film and provides hardness and abrasion resistance. The vehicle is an oily liquid that dissolves the base and pigment and allows the paint to spread easily. Pigments provide color. Thinners increase fluidity and penetration while dryers accelerate drying. Good paints apply smoothly, dry quickly to a durable film without cracks or brush marks, and maintain their color without fading over time. Old paint can be removed by burning, chemical strippers, or alkaline solutions left on the surface.
Lightweight concrete has a lower density than ordinary concrete due to the use of lightweight aggregates. It has strengths between 7-40 MPa, improved workability, thermal insulation, and water absorption. Lightweight concrete exhibits higher moisture movement and fire resistance compared to ordinary concrete. It is used in prestressed concrete, high-rise buildings, and to reduce dead load. While more expensive, it allows for rapid, simple construction and reduced transportation costs.
The presentation that will cover the main topics of concreting methods in cold weather and discussion about the durabiity of concrete and also useful tips for designing the mix of concrete
The document discusses different types of bricks used in construction. It describes the manufacturing process which involves preparing clay, moulding, drying, and burning bricks either in clamps or kilns. Bricks are categorized as burnt or unburnt, with burnt bricks further divided into four classes based on their quality. The document provides details on the water absorption rates and compressive strengths of different brick classes. It also outlines qualities of good bricks and lists some major brick manufacturing plants in Pakistan.
The document outlines the American Concrete Institute's (ACI) standard method for designing concrete mixes. It describes the basic considerations that must be taken into account, including cost, specifications, workability, and strength/durability. The ACI 211 method aims to produce mixes with acceptable workability, durable/strong hardened concrete, and economic efficiency. Key steps include determining compressive strength, water-cement ratio, air content, slump, water content, cement content, coarse aggregate content, fine aggregate content, and adjusting for aggregate moisture. The mix design is checked and adjusted through laboratory testing.
Alkali-aggregate reaction is the reaction between the active mineral constituents of some aggregates and the alkali hydroxides in concrete. It is only harmful when it produces significant expansion. There are two main forms: alkali-silica reaction and alkali-carbonate reaction.
Alkali-silica reaction, also known as ASR, causes cracking in concrete from the reaction between certain reactive minerals or rocks in aggregates and alkalis in cement. It can cause visible symptoms like cracking and pop outs, which are small fragment breakaways leaving shallow depressions.
Alkali-carbonate reaction is influenced by factors like clay or calcite/dolomite content and crystal size in aggregates.
Low power architecture of logic gates using adiabatic techniquesnooriasukmaningtyas
The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
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%.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
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.
5. HISTORY OF ADMIXTURES:
• Admixtures have been used in concrete and mortar since at least the Roman
Empire. The Romans found that certain materials such as milk, blood and
lard, as well as organic materials such as molasses, eggs and rice paste allow
greater workability in cementitious mixtures.
• While the first patent for calcium chloride in concrete goes all the way back
to 1873 in Germany, modern admixture technology started with basic air-
entraining agents, retarders, accelerators and water reducers in the 1930s in
North America.
• However, it was not until the 1950s that these types of products began to
see widespread use in concrete. ASTM first published its C494 standard in
1962, now titled “Historical Standard: Standard Specification for Chemical
Admixtures for Concrete,” which set performance criteria for five types of
admixtures: A, B, C, D and E. Types F and G, high-range water-reducing
admixtures, were not added to the C494 standard until 1980. In 1962, only
36 states required or allowed the use of admixtures in concrete.
6. • ACI Committee 212 publishes the “Report on Chemical Admixtures for Concrete,”
which did not include high-range water reducers in their document until 1981. While
the 1970s saw a sharp increase in the use of admixtures in concrete, a 1982 survey
found that only 71% of the concrete produced in the United States contained water-
reducing admixtures, and that less than 2% contained (High Range Water Reducers),
• In 1979, the first corrosion-inhibiting admixture was introduced to help mitigate the
impact of chloride salt (NaCl) attack on steel reinforcement. Almost 20 years later
(1996), shrinkage-reducing admixtures followed and helped to address cracking issues
associated with autogenous drying in high-performance concrete.
• The 1980s and ’90s continued to see increased use of admixtures in concrete, which
included significantly more frequent projects specifying the use of High Range Water
Reducers as the placement benefits of higher slumps and improved durability of lower
water-cementitious material (w/c) ratio concretes were realized.
• Still, the biggest change in concrete in North America occurred with the introduction
of a new High Range Water Reducers technology that greatly expanded the plastic
and hardened properties of concrete and, in the case of SCC, created a new
concrete terminology.
7. POLYCARBOXYLATES AND SCC:
• In the mid 1990s, polycarboxylates in High Range Water Reducers
admixtures were introduced in North America, thus initiating a dramatic
paradigm change in our understanding of how to design and use highly
workable concrete mixtures. Because of the flexibility, enhanced
workability, workability retention with minimal set retardation, and very
good finishing characteristics, the acceptance curve for these
admixtures was much shorter than anything previously introduced.
• Shortly after the introduction of polycarboxylate-based High Range
Water Reducers, concrete producers began experimenting with SCC in
all segments of concrete production; however, nowhere was SCC more
rapidly accepted than in the precast market. The ability to fill a mold
quickly without vibration, while still maintaining or even improving the
plastic and hardened properties of the concrete, made SCC a perfect
match for precast concrete producers.
8. • Precasters began using terms like slump flow, viscosity, filling ability, passing
ability and rheology to describe this revolutionary type of self-consolidating
and non-segregating concrete. Unlike earlier High Range Water Reducers
technologies such as naphthalene (C10H8) and melamine sulfonate (CH3SO2O)
condensates, which have fixed-chemistry and limited-performance capability,
polycarboxylate technology is highly flexible, meaning that the
polycarboxylate polymer can be designed and optimized for a wide range of
performance requirements, from high early strength to extended slump life to
SCC.
• With the emergence of SCC, another class of chemical admixtures –
viscosity-modifying admixtures – have been commercialized to address the
need for improving the water tolerance and segregation resistance of this
highly flowable concrete. The rapid acceptance of VMAs (Viscosity Modifying
Admixtures) promoted the inclusion of a new admixture category, Type S, in
the ASTM C494 standard to assure users that VMAs have no impact on
common concrete properties (workability, set, strength and shrinkage).
9. WHERE ARE WE NOW?
• A list of the most recent chemical admixtures relevant to precast
concrete is as follows:
• High Early Strength – A polycarboxylate-based HRWR designed and
formulated to enable increased strength at early ages.
• Extended Slump Life HRWR – These admixtures are typically blends of
different polycarboxylates, which are engineered to activate or increase
slump at different times. The goal of these polycarboxylate-blended
products is to maintain concrete mixtures at target workability levels
until concrete is placed and consolidated without delaying set times.
Several HRWR products have been recently introduced, comprised solely
of slowly activating polycarboxylates, which can be added to almost any
concrete mix to extend slump life as desired.
10. • Rheology Modifying Admixtures – These admixtures are designed to impart
lubricity to the concrete, especially at very low slumps, resulting in improved
formed finish, increased productivity and improved surface texture.
• Viscosity Modifying Admixtures (VMAs) – Viscosity modifying admixtures are
most commonly used in SCC when the batch-to-batch variations in aggregate
gradation, particle shape and density, and water content make it difficult to
consistently produce a stable, non-segregating SCC mix. VMAs function by
building a network structure within the pore water that helps minimize water
and paste movement, especially once the concrete is in a static state. VMAs
have also been used with conventional concrete mixes where the concrete mix
may have a tendency to segregate.
11. WHERE DO WE GO FROM HERE?
• Polycarboxylate HRWRs will continue to be the dominant admixture
technology, especially in precast concrete. As a result of continually improving
the dose efficiency of polycarboxylates, they are already penetrating into
normal water-reducing and water-reducing/retarding chemical admixtures.
Engineering or designing polycarboxylates to create or modify a specific
performance attribute of the concrete mix will also likely be expanded.
• Other products that may be on the horizon:
• Universal Air-Entraining Admixtures –
• The search continues for “set it and forget it” air entrainment. Some work
has been successful, and so admixture providers may not be far away from a
product that will allow precast manufacturers to add an admixture to achieve
a specific air target and be far less sensitive to the many factors that
affect air content.
12. • High Range Water Reducers(HRWRs) :
• Polycarboxylate technology will continue to be exploited to push the concrete
performance envelope. New polycarboxylate-based HRWRs can include admixtures
that allow for higher levels of water reduction without compromising concrete
workability; admixtures with shrinkage reducing capability; and admixtures for
high early strength.
• SUPPLY CHAIN MANAGEMENT (SCM) Activators:
• In the push to use more fly ash and slag in precast, admixtures will be required
to offset the early strength loss experienced when using fly ash or slag.
4. Nanotechnology – This has become quite the buzzword in many industries, and
the concrete industry is no exception. A few products, based on aqueous
suspensions of nano silica have already been commercially introduced into the
concrete market. These products are designed to significantly improve early
strength development. The benefits from nanotechnology are realized from the
very high surface area that nano particles provide versus ordinary portland
cement.
13. •Internal Curing Admixtures (ICAs):
• Controlled release of ICAs for high-performance concretes is
expected to help mitigate cracking due to autogenous drying
shrinkage. The combination of ICA could represent an interesting
synergistic approach to controlling cracks in low w/c ratio
concrete.
• While the past 20 years have seen amazing changes in the precast
concrete industry, new innovative chemical admixtures are coming
on stage to meet the increased demand for sustainable concrete,
faster construction cycles and growing shortages of quality raw
materials.