(1) The document discusses the durability and serviceability of concrete. It defines durability as the ability to resist weathering and chemical attacks. (2) The resistance of concrete depends on its quality, constituent materials, and curing process. Well-made concrete that is properly compacted and cured can remain durable if micro-cracks do not connect to the surface. (3) The document presents three holistic models of deterioration in reinforced concrete. The first two models describe a two-stage process where micro-cracks first interconnect, then allow water and chemicals to penetrate and cause damage. The third model emphasizes the role of water cement ratio and the interaction of porosity, chemicals, and intermittent water presence in causing
This document discusses quality control in concrete construction. It explains that concrete is made by mixing cement, fine aggregate, coarse aggregate, water, and admixtures. Quality control is important to ensure the concrete has strength, durability, and aesthetics. Quality control involves testing the materials used, the fresh concrete mix, and the hardened concrete. Tests on fresh concrete include slump and compacting factor tests, while tests on hardened concrete include compression, tensile, and flexural strength tests. The document outlines the quality control process from the production of materials to placement and curing of the concrete.
This document outlines 8 techniques for repairing cracks in concrete structures: 1) Sealing with epoxies, 2) Routing and sealing, 3) Stitching, 4) External stressing, 5) Overlays, 6) Grouting, 7) Blanketing, and 8) Autogenous healing. Sealing with epoxies involves injecting epoxy compounds into cracks at high pressure. Routing and sealing enlarges cracks and fills them with sealants. Stitching reestablishes tensile strength across major cracks using metal units drilled into crack walls. External stressing closes cracks by applying compression to overcome tensile stresses. Overlays provide a sealed surface for multiple cracks. Grouting is an alternative
This document discusses various techniques for repairing and rehabilitating concrete structures. It covers topics such as concrete deterioration mechanisms, materials used for repair like cement mortars and polymers, and techniques like grouting, jacketing, and external bonding. Assessment of damaged structures involves preliminary investigation, detailed investigation using techniques like core cutting, rebar location, corrosion measurement, and pull-out tests to determine repair requirements. Underwater repair of structures also requires special considerations and techniques.
This document discusses quality control and durability factors in concrete. It defines quality as conformance to requirements and durability as a concrete's ability to resist deterioration when exposed to the environment. Several factors influence concrete durability, including the materials used, water-cement ratio, compaction, curing and the physical and chemical conditions of the service environment. Common durability issues include corrosion, cracking from sulfate attack or alkali-silica reaction, and carbonation reducing alkalinity. Proper quality control of materials and construction processes is needed to produce durable concrete.
The document provides an introduction to the repair and rehabilitation of structures. It discusses factors contributing to damages in buildings from construction through use. Common causes of distress in concrete structures are then outlined, including construction errors, environmental factors, and chemical reactions. The objectives of conducting a condition survey of a distressed structure are presented, including identifying causes and assessing the extent of damage. The stages of a condition survey are described, beginning with a preliminary inspection, planning, visual inspection, and potentially field and laboratory testing. Classification of damage into different classes is also covered to help assess repair needs.
NDT techniques can evaluate concrete structures in a non-destructive manner by assessing strength, quality, and durability without damaging the concrete. Some key NDT tests described in the document include rebound hammer testing to estimate concrete strength, UPV testing to evaluate homogeneity and detect cracks or voids, half-cell potential testing to assess corrosion risk, and cover meter testing to determine reinforcement location and concrete cover thickness. NDT allows for more extensive evaluation than destructive testing methods at a lower cost. Test results are influenced by factors like moisture, temperature, reinforcement properties, and concrete composition.
Properties of Fresh and Hardened ConcreteRishabh Lala
1. The document discusses the properties of fresh and hardened concrete, including workability, strength, permeability, and durability.
2. Workability of fresh concrete refers to the effort required to mix and place the concrete without segregation. It is measured by tests like slump.
3. Compressive strength is an important property of hardened concrete, as concrete is designed to resist compressive loads. Strength depends on factors like water-cement ratio and compaction.
4. Permeability and durability are also important properties, as permeability affects how easily substances like water or salts can pass through concrete. Low permeability leads to higher durability.
This document discusses quality control of concrete through various tests on fresh and hardened concrete. It begins with an introduction to concrete and quality, then discusses where quality control begins in the production of materials and continues through handling, batching, mixing, transporting and placing concrete. Key tests on fresh concrete include slump and compacting factor tests, while tests on hardened concrete include compression, tensile strength, and flexural strength tests to evaluate the quality and strength of the concrete. The document also reviews materials used in concrete such as cement, water, aggregates, and admixtures.
This document discusses quality control in concrete construction. It explains that concrete is made by mixing cement, fine aggregate, coarse aggregate, water, and admixtures. Quality control is important to ensure the concrete has strength, durability, and aesthetics. Quality control involves testing the materials used, the fresh concrete mix, and the hardened concrete. Tests on fresh concrete include slump and compacting factor tests, while tests on hardened concrete include compression, tensile, and flexural strength tests. The document outlines the quality control process from the production of materials to placement and curing of the concrete.
This document outlines 8 techniques for repairing cracks in concrete structures: 1) Sealing with epoxies, 2) Routing and sealing, 3) Stitching, 4) External stressing, 5) Overlays, 6) Grouting, 7) Blanketing, and 8) Autogenous healing. Sealing with epoxies involves injecting epoxy compounds into cracks at high pressure. Routing and sealing enlarges cracks and fills them with sealants. Stitching reestablishes tensile strength across major cracks using metal units drilled into crack walls. External stressing closes cracks by applying compression to overcome tensile stresses. Overlays provide a sealed surface for multiple cracks. Grouting is an alternative
This document discusses various techniques for repairing and rehabilitating concrete structures. It covers topics such as concrete deterioration mechanisms, materials used for repair like cement mortars and polymers, and techniques like grouting, jacketing, and external bonding. Assessment of damaged structures involves preliminary investigation, detailed investigation using techniques like core cutting, rebar location, corrosion measurement, and pull-out tests to determine repair requirements. Underwater repair of structures also requires special considerations and techniques.
This document discusses quality control and durability factors in concrete. It defines quality as conformance to requirements and durability as a concrete's ability to resist deterioration when exposed to the environment. Several factors influence concrete durability, including the materials used, water-cement ratio, compaction, curing and the physical and chemical conditions of the service environment. Common durability issues include corrosion, cracking from sulfate attack or alkali-silica reaction, and carbonation reducing alkalinity. Proper quality control of materials and construction processes is needed to produce durable concrete.
The document provides an introduction to the repair and rehabilitation of structures. It discusses factors contributing to damages in buildings from construction through use. Common causes of distress in concrete structures are then outlined, including construction errors, environmental factors, and chemical reactions. The objectives of conducting a condition survey of a distressed structure are presented, including identifying causes and assessing the extent of damage. The stages of a condition survey are described, beginning with a preliminary inspection, planning, visual inspection, and potentially field and laboratory testing. Classification of damage into different classes is also covered to help assess repair needs.
NDT techniques can evaluate concrete structures in a non-destructive manner by assessing strength, quality, and durability without damaging the concrete. Some key NDT tests described in the document include rebound hammer testing to estimate concrete strength, UPV testing to evaluate homogeneity and detect cracks or voids, half-cell potential testing to assess corrosion risk, and cover meter testing to determine reinforcement location and concrete cover thickness. NDT allows for more extensive evaluation than destructive testing methods at a lower cost. Test results are influenced by factors like moisture, temperature, reinforcement properties, and concrete composition.
Properties of Fresh and Hardened ConcreteRishabh Lala
1. The document discusses the properties of fresh and hardened concrete, including workability, strength, permeability, and durability.
2. Workability of fresh concrete refers to the effort required to mix and place the concrete without segregation. It is measured by tests like slump.
3. Compressive strength is an important property of hardened concrete, as concrete is designed to resist compressive loads. Strength depends on factors like water-cement ratio and compaction.
4. Permeability and durability are also important properties, as permeability affects how easily substances like water or salts can pass through concrete. Low permeability leads to higher durability.
This document discusses quality control of concrete through various tests on fresh and hardened concrete. It begins with an introduction to concrete and quality, then discusses where quality control begins in the production of materials and continues through handling, batching, mixing, transporting and placing concrete. Key tests on fresh concrete include slump and compacting factor tests, while tests on hardened concrete include compression, tensile strength, and flexural strength tests to evaluate the quality and strength of the concrete. The document also reviews materials used in concrete such as cement, water, aggregates, and admixtures.
This document discusses fresh concrete and factors that affect its workability. It describes workability as the ease with which concrete can be mixed, placed, and compacted. Key factors that influence workability include water content, aggregate size and shape, admixtures, aggregate surface texture, and aggregate grading. Common tests to measure workability are the slump test, compacting factor test, and VeeBee consistometer test. The document also covers segregation and bleeding of concrete, their causes, and methods to prevent them.
Concrete is a widely used construction material consisting of cement, water, and aggregates. The strength of concrete is specified using its 28-day cube strength in N/sq.mm. Formwork is used to mold wet concrete into desired shapes and allow it to cure. Formwork design involves choosing traditional or systematic approaches using wood or steel components like props, beams, sheathing to form columns, walls, and beams until the concrete gains sufficient strength. Proper formwork is important for quality concrete finish and structural integrity.
Curing concrete is important to allow the cement hydration process to continue and develop strength over time. Proper curing ensures concrete reaches its designed strength and durability by controlling moisture loss. Common curing methods include water curing through ponding, sprinkling or wet coverings; membrane curing using plastic sheeting or curing compounds; and steam curing to accelerate strength gain. Curing should continue for at least 7 days for normal concrete and 14 days if blended cements are used. Inadequate curing can lead to reduced strength, increased permeability and poor durability.
Causes of deterioration of concrete structuresKarthi Kavya
The document discusses types of deterioration that can occur in concrete structures. It identifies three main types: distress in concrete, permeability of concrete, and aggressive deterioration agents. Distress can be physical, chemical, or mechanical due to issues like high water-cement ratio, inadequate curing, poor aggregates, overloading, or design deficiencies. Permeability is increased by porosity, microcracks, and dampness/seepage, allowing chemicals to enter. Major agents are chlorides, sulfates, and alkali-silica reaction, which can cause corrosion, cracking, or expansion through carbonation, sulfate attack, or silica gel formation.
This document provides an overview of concrete, including its composition, properties, production process, and testing. Some key points:
- Concrete is a composite material made of cement, fine and coarse aggregates, and water. It can be classified based on its cementing material, mix proportions, performance specifications, grade, density, and place of casting.
- The production of concrete involves batching, mixing, transporting, placing, compacting, curing, and finishing. Proper batching and mixing are important to ensure uniform strength. Compaction removes entrapped air for maximum strength. Curing maintains moisture for proper hardening.
- Concrete properties depend on water-cement ratio, with maximum theoretical
Project report on self compacting concreterajhoney
This project report summarizes research conducted on developing self-compacting concrete using industrial waste. A group of students conducted the research under the guidance of Prof. M. B. Kumthekar to fulfill requirements for a B.E. in Civil Engineering from Shivaji University, Kolhapur. The report documents the need for self-compacting concrete to improve construction efficiency and concrete quality. It describes tests conducted to utilize red mud and foundry waste sand as partial replacements for cement in self-compacting concrete mixtures and analyze the results.
This document discusses using a scientific approach to determine the workability of concrete by measuring its rheological properties. It outlines that workability is traditionally determined through empirical tests like slump tests, which have limitations. Rheology allows measurement of yield stress and plastic viscosity, parameters that better describe concrete flow. Various rheometers are described that can measure these properties, like coaxial cylinder and parallel plate devices. Factors influencing concrete rheology are also discussed. The document concludes workability should be evaluated based on rheological measurements to address limitations of empirical tests.
This document discusses concrete distress, its causes, and concrete repair systems. It defines distress as damage to concrete that can occur during production or service life due to varying conditions. Common causes of distress include structural loads, errors in design and construction, drying shrinkage, corrosion, and deterioration over time from chemical reactions, freezing/thawing, or weathering. Proper concrete repair requires determining the cause of damage, evaluating its extent, selecting repair methods, preparing the surface, applying repair materials, and curing. Durable repairs depend on high quality workmanship and materials to ensure the repair is well-bonded and resistant to future distress.
Concrete Mix design with the recommendation of IS10262:2009. Also discussed the differences between the IS10262:2009 and IS10262:1982.
The major content of presentation are:
Scope
Introduction
Factors affected mix design
Mix Design
Differences b/w IS10262:1982 and 10262:2009
Exercise
Non-Destructive Testing of Concrete In Structures26032015
Ultrasonic pulse velocity testing, rebound hammer testing, and cover meter testing are three common non-destructive testing methods for concrete structures. Ultrasonic pulse velocity testing uses transducers to transmit and receive ultrasonic pulses through concrete to assess properties like strength and uniformity without damage. Rebound hammer testing measures surface hardness through a spring-controlled hammer's rebound, indicating relative concrete strength. Cover meters use electromagnetic principles to locate and measure rebar cover thickness in concrete. Non-destructive testing provides important information on structural condition and performance without damaging the structure.
Ultrasonic pulse velocity test for concreteCivil Engineer
Ultrasonic pulse velocity (UPV) testing uses ultrasonic waves to assess the quality and uniformity of concrete in a non-destructive manner. UPV testing involves transmitting ultrasonic pulses through concrete and measuring the transit time, from which the pulse velocity can be calculated. Higher pulse velocities indicate higher quality concrete with fewer voids or defects. UPV testing can detect voids, cracks, and changes in concrete properties. It provides information on concrete strength and uniformity that can be used to evaluate structures and estimate deterioration.
This document discusses quality assurance for concrete construction. It outlines three key components of a quality management system: 1) a quality assurance plan, 2) quality control process, and 3) quality audits. The quality assurance plan establishes organizational responsibilities, control measures, acceptance criteria, and documentation requirements. Quality control ensures conformance to specifications. Quality audits verify that quality assurance and control programs are properly implemented. Factors that affect concrete properties like strength, permeability, cracking and durability are also summarized.
MEANING OF MIX DESIGN
GRADE OF CONCRETE.
FACTORS INFLUCING THE CHOICE OF MIX DESIGN.
MATHODS OF CONCRETE MIX DESIGN
MIX DESIGN BY INDIAN STANDARD METHOD.
The document discusses concrete mix design, including:
- Concrete is made from cement, aggregates, water, and sometimes admixtures.
- ACI and BIS methods are described for determining mix proportions based on factors like strength, workability, durability, and materials.
- A step-by-step example is provided to design a mix using the ACI method for a specified 30MPa strength, including determining water-cement ratio, volumes, and final proportions.
1. Concrete repair refers to modifying damaged concrete structures to restore their load-bearing capacity and durability.
2. Common repair techniques include removing damaged concrete and replacing it with new concrete.
3. Shotcreting is a repair method that projects a concrete mixture at high velocity to repair large areas or strengthen structures. It produces a dense, homogeneous material without formwork.
This document discusses types of waste materials that can be used to produce waste material based concrete, including organic waste like rice husk, inorganic waste like broken concrete and glass, and industrial wastes like blast furnace slag, coal ash, and red mud. Rice husk can be used to produce lightweight concrete, while broken concrete and glass can produce concrete of sufficient strength. Blast furnace slag and coal ash can partially replace cement and improve properties like chemical resistance. Silica fume can significantly increase strength and allow high water-cement ratios. Using these wastes can reduce costs and environmental impacts of concrete production.
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.
Concrete permeability is a key factor in its durability. Permeability is affected by water-cement ratio, with lower ratios producing less permeable concrete. Curing also impacts permeability. Proper curing, including moist curing, produces less permeable concrete. Permeability testing involves measuring water flow through a sample over time under pressure. Sulfate attack can occur when sulfates penetrate permeable concrete and form expansive compounds that crack the material. Resistance to sulfates is improved with lower permeability concrete.
This document discusses repairs, rehabilitation, and retrofitting of structures. It begins by defining repair, rehabilitation, and retrofitting. Repair returns a structure to its previous condition without improving strength. Rehabilitation considers strength by repairing damage. Retrofitting modifies existing structures to increase resistance to hazards like earthquakes. It provides examples of each process. The document outlines evaluation and quality control methods for repairs. It also discusses materials and techniques used for crack repair in structures, including epoxy injection grouting. Overall, the document provides an overview of restoring and upgrading structures through various repair, rehabilitation, and retrofitting methods.
Chapter 3 materials & techniques for repairsAnkit Patel
The document discusses various types of polymer concrete, including polymer impregnated concrete (PIC), polymer Portland cement concrete (PPCC), and polymer concrete (PC). PIC involves impregnating hardened Portland cement concrete with a monomer, then polymerizing it in place. PPCC is produced by incorporating a polymer or monomer emulsion into ordinary concrete. PC uses a polymer as the sole binder instead of Portland cement. Polymer concrete has improved strength, adhesion, chemical resistance, impact resistance, and impermeability compared to ordinary concrete.
This document discusses fresh concrete and factors that affect its workability. It describes workability as the ease with which concrete can be mixed, placed, and compacted. Key factors that influence workability include water content, aggregate size and shape, admixtures, aggregate surface texture, and aggregate grading. Common tests to measure workability are the slump test, compacting factor test, and VeeBee consistometer test. The document also covers segregation and bleeding of concrete, their causes, and methods to prevent them.
Concrete is a widely used construction material consisting of cement, water, and aggregates. The strength of concrete is specified using its 28-day cube strength in N/sq.mm. Formwork is used to mold wet concrete into desired shapes and allow it to cure. Formwork design involves choosing traditional or systematic approaches using wood or steel components like props, beams, sheathing to form columns, walls, and beams until the concrete gains sufficient strength. Proper formwork is important for quality concrete finish and structural integrity.
Curing concrete is important to allow the cement hydration process to continue and develop strength over time. Proper curing ensures concrete reaches its designed strength and durability by controlling moisture loss. Common curing methods include water curing through ponding, sprinkling or wet coverings; membrane curing using plastic sheeting or curing compounds; and steam curing to accelerate strength gain. Curing should continue for at least 7 days for normal concrete and 14 days if blended cements are used. Inadequate curing can lead to reduced strength, increased permeability and poor durability.
Causes of deterioration of concrete structuresKarthi Kavya
The document discusses types of deterioration that can occur in concrete structures. It identifies three main types: distress in concrete, permeability of concrete, and aggressive deterioration agents. Distress can be physical, chemical, or mechanical due to issues like high water-cement ratio, inadequate curing, poor aggregates, overloading, or design deficiencies. Permeability is increased by porosity, microcracks, and dampness/seepage, allowing chemicals to enter. Major agents are chlorides, sulfates, and alkali-silica reaction, which can cause corrosion, cracking, or expansion through carbonation, sulfate attack, or silica gel formation.
This document provides an overview of concrete, including its composition, properties, production process, and testing. Some key points:
- Concrete is a composite material made of cement, fine and coarse aggregates, and water. It can be classified based on its cementing material, mix proportions, performance specifications, grade, density, and place of casting.
- The production of concrete involves batching, mixing, transporting, placing, compacting, curing, and finishing. Proper batching and mixing are important to ensure uniform strength. Compaction removes entrapped air for maximum strength. Curing maintains moisture for proper hardening.
- Concrete properties depend on water-cement ratio, with maximum theoretical
Project report on self compacting concreterajhoney
This project report summarizes research conducted on developing self-compacting concrete using industrial waste. A group of students conducted the research under the guidance of Prof. M. B. Kumthekar to fulfill requirements for a B.E. in Civil Engineering from Shivaji University, Kolhapur. The report documents the need for self-compacting concrete to improve construction efficiency and concrete quality. It describes tests conducted to utilize red mud and foundry waste sand as partial replacements for cement in self-compacting concrete mixtures and analyze the results.
This document discusses using a scientific approach to determine the workability of concrete by measuring its rheological properties. It outlines that workability is traditionally determined through empirical tests like slump tests, which have limitations. Rheology allows measurement of yield stress and plastic viscosity, parameters that better describe concrete flow. Various rheometers are described that can measure these properties, like coaxial cylinder and parallel plate devices. Factors influencing concrete rheology are also discussed. The document concludes workability should be evaluated based on rheological measurements to address limitations of empirical tests.
This document discusses concrete distress, its causes, and concrete repair systems. It defines distress as damage to concrete that can occur during production or service life due to varying conditions. Common causes of distress include structural loads, errors in design and construction, drying shrinkage, corrosion, and deterioration over time from chemical reactions, freezing/thawing, or weathering. Proper concrete repair requires determining the cause of damage, evaluating its extent, selecting repair methods, preparing the surface, applying repair materials, and curing. Durable repairs depend on high quality workmanship and materials to ensure the repair is well-bonded and resistant to future distress.
Concrete Mix design with the recommendation of IS10262:2009. Also discussed the differences between the IS10262:2009 and IS10262:1982.
The major content of presentation are:
Scope
Introduction
Factors affected mix design
Mix Design
Differences b/w IS10262:1982 and 10262:2009
Exercise
Non-Destructive Testing of Concrete In Structures26032015
Ultrasonic pulse velocity testing, rebound hammer testing, and cover meter testing are three common non-destructive testing methods for concrete structures. Ultrasonic pulse velocity testing uses transducers to transmit and receive ultrasonic pulses through concrete to assess properties like strength and uniformity without damage. Rebound hammer testing measures surface hardness through a spring-controlled hammer's rebound, indicating relative concrete strength. Cover meters use electromagnetic principles to locate and measure rebar cover thickness in concrete. Non-destructive testing provides important information on structural condition and performance without damaging the structure.
Ultrasonic pulse velocity test for concreteCivil Engineer
Ultrasonic pulse velocity (UPV) testing uses ultrasonic waves to assess the quality and uniformity of concrete in a non-destructive manner. UPV testing involves transmitting ultrasonic pulses through concrete and measuring the transit time, from which the pulse velocity can be calculated. Higher pulse velocities indicate higher quality concrete with fewer voids or defects. UPV testing can detect voids, cracks, and changes in concrete properties. It provides information on concrete strength and uniformity that can be used to evaluate structures and estimate deterioration.
This document discusses quality assurance for concrete construction. It outlines three key components of a quality management system: 1) a quality assurance plan, 2) quality control process, and 3) quality audits. The quality assurance plan establishes organizational responsibilities, control measures, acceptance criteria, and documentation requirements. Quality control ensures conformance to specifications. Quality audits verify that quality assurance and control programs are properly implemented. Factors that affect concrete properties like strength, permeability, cracking and durability are also summarized.
MEANING OF MIX DESIGN
GRADE OF CONCRETE.
FACTORS INFLUCING THE CHOICE OF MIX DESIGN.
MATHODS OF CONCRETE MIX DESIGN
MIX DESIGN BY INDIAN STANDARD METHOD.
The document discusses concrete mix design, including:
- Concrete is made from cement, aggregates, water, and sometimes admixtures.
- ACI and BIS methods are described for determining mix proportions based on factors like strength, workability, durability, and materials.
- A step-by-step example is provided to design a mix using the ACI method for a specified 30MPa strength, including determining water-cement ratio, volumes, and final proportions.
1. Concrete repair refers to modifying damaged concrete structures to restore their load-bearing capacity and durability.
2. Common repair techniques include removing damaged concrete and replacing it with new concrete.
3. Shotcreting is a repair method that projects a concrete mixture at high velocity to repair large areas or strengthen structures. It produces a dense, homogeneous material without formwork.
This document discusses types of waste materials that can be used to produce waste material based concrete, including organic waste like rice husk, inorganic waste like broken concrete and glass, and industrial wastes like blast furnace slag, coal ash, and red mud. Rice husk can be used to produce lightweight concrete, while broken concrete and glass can produce concrete of sufficient strength. Blast furnace slag and coal ash can partially replace cement and improve properties like chemical resistance. Silica fume can significantly increase strength and allow high water-cement ratios. Using these wastes can reduce costs and environmental impacts of concrete production.
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.
Concrete permeability is a key factor in its durability. Permeability is affected by water-cement ratio, with lower ratios producing less permeable concrete. Curing also impacts permeability. Proper curing, including moist curing, produces less permeable concrete. Permeability testing involves measuring water flow through a sample over time under pressure. Sulfate attack can occur when sulfates penetrate permeable concrete and form expansive compounds that crack the material. Resistance to sulfates is improved with lower permeability concrete.
This document discusses repairs, rehabilitation, and retrofitting of structures. It begins by defining repair, rehabilitation, and retrofitting. Repair returns a structure to its previous condition without improving strength. Rehabilitation considers strength by repairing damage. Retrofitting modifies existing structures to increase resistance to hazards like earthquakes. It provides examples of each process. The document outlines evaluation and quality control methods for repairs. It also discusses materials and techniques used for crack repair in structures, including epoxy injection grouting. Overall, the document provides an overview of restoring and upgrading structures through various repair, rehabilitation, and retrofitting methods.
Chapter 3 materials & techniques for repairsAnkit Patel
The document discusses various types of polymer concrete, including polymer impregnated concrete (PIC), polymer Portland cement concrete (PPCC), and polymer concrete (PC). PIC involves impregnating hardened Portland cement concrete with a monomer, then polymerizing it in place. PPCC is produced by incorporating a polymer or monomer emulsion into ordinary concrete. PC uses a polymer as the sole binder instead of Portland cement. Polymer concrete has improved strength, adhesion, chemical resistance, impact resistance, and impermeability compared to ordinary concrete.
The document discusses repair and rehabilitation of concrete structures. It describes various causes of distress in concrete structures including structural causes, errors in design/construction, chemical reactions, and weathering. It then outlines the evaluation process for repair projects, including visual inspection, non-destructive testing, and laboratory testing to determine the extent of damage and appropriate repair methods. Specific causes of reinforcement corrosion like cracks, moisture, and concrete permeability are explained along with remedial measures.
This document discusses materials used for repair, surface coatings, and polyester resins. It describes various types of materials used for repair like cement, polymers, epoxy resins and chemicals. It also discusses essential parameters for surface coatings like bonding strength, durability and permeability. Different types of surface coatings like solvent-based, solvent-free and water-based are described. Properties and applications of polyester resins are provided.
Durability is the ability of concrete to resist weathering actions, chemical attacks, and abrasion while maintaining its desired engineering properties. A durable concrete structure withstands deterioration over its design life through exposure to the environment. Factors that influence durability include the water-cement ratio, cement content, cover thickness, type of aggregates used, and curing of the concrete. Permeability is an important indicator of durability, with lower permeability reducing susceptibility to chemical attacks. Proper compaction and curing help reduce the permeability of concrete.
The document discusses the durability of concrete and the factors that affect it. It defines durability as the ability of concrete to resist weathering, chemical attack, and abrasion while maintaining its desired properties. The main factors discussed are abrasion, biological factors, temperature effects, freezing and thawing, and various types of chemical attacks including carbonation, chloride attack, acid attack, and sulfate attack. Prevention and mitigation methods are provided for each factor.
This document provides information about a presentation on concrete durability given by Eng. B. Sambasiva Rao. It includes his curriculum vitae, definitions of durability, factors affecting concrete durability like permeability and chloride attacks. It also discusses production of concrete, case studies of old durable structures, and common concrete failures. A case study is presented of the Al Hail Green Residential Development in Muscat where the chloride penetration was monitored monthly.
It contains lots of images and videos which can easily explain the processes.
It contains 48 slides and crucial information for demolition of structures.
This document discusses the durability and permeability of concrete. It defines durability as the ability to last a long time without significant deterioration. Permeability is defined as the property that governs the rate of flow of a fluid into a porous solid. The document discusses factors that affect the durability and permeability of concrete such as water-cement ratio, cement properties, aggregate type and quality, curing methods, and use of admixtures. Maintaining a low water-cement ratio and limiting chloride and sulfate levels in concrete are important for ensuring durability.
The document provides guidelines for repair and rehabilitation of existing reinforced concrete buildings. It discusses causes of concrete deterioration like permeability, aggressive agents, and condition surveys. Non-destructive tests are recommended to evaluate concrete quality, cracking, and corrosion. The approach involves identifying deterioration causes, assessing damage extent, and selecting appropriate repair materials and methods to rehabilitate structures in a systematic and cost-effective manner.
Reasons and solution to cracks in buildings.
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The document provides information about demolition techniques and safety precautions for demolition. It discusses demolition methods such as manual demolition, demolition by machines, demolition by hydraulic crushers, demolition by wrecking ball, and demolition by explosives including implosion. It also outlines the typical demolition sequence and covers safety topics like protective equipment, temporary supports, training, equipment maintenance, and debris handling.
Serviceability limit states refer to how structures perform under normal loads and consider how structures are used. Serviceability looks at deflections, cracks, vibrations, surface deterioration, and corrosion that don't cause collapse but make structures unfit for use. Periodic inspections of existing buildings should be implemented to identify structural defects, distress, material deterioration, overloading, and unauthorized work to avoid disaster and extend a structure's typical 50-year service life through repairs and maintenance. As-built drawings are important for engineers to properly assess structures.
Freddy Jiménez, un pequeño agricultor y ganadero, escribe al Presidente Correa para pedir ayuda con problemas de tierras y corrupción. Comuneros se han adueñado de sus tierras a pesar de tener escrituras, y funcionarios de SIGTIERRAS y jueces demoran los procesos y cobran altas tarifas. También pide créditos para proyectos agrícolas, semillas gratuitas, y protección contra precios bajos de sus cosechas. Desea erradicar la corrupción que afecta especialmente a los más p
Bamzy Baby Productions proposes providing phonics workbooks and educational materials featuring the character Bamzy Baby to help improve early childhood literacy and development. The workbooks and materials are designed to develop phonemic awareness, fine motor skills, and critical thinking through activities, stories, and interactive performances. The proposal outlines pricing for assembly presentations, workbooks, music, apparel, and honors recognition using Bamzy Baby's "Thinking Cap" concept to promote academic achievement.
La educación es el proceso de facilitar el aprendizaje a través de la transmisión de conocimientos, habilidades, valores y creencias de un grupo a otro. La educación puede ocurrir de manera formal en instituciones educativas o de manera no formal a través de experiencias que influyen en cómo uno piensa y actúa. La educación formal se divide en etapas como preescolar, primaria, secundaria, universidad, mientras que la educación no formal ocurre fuera del sistema escolar de manera opcional pero organizada.
El reciclaje convierte desechos en nuevos productos o materia prima para reducir el uso de recursos, la contaminación y las emisiones de gases de efecto invernadero. Es un componente clave para reducir desechos modernos y reutiliza o recicla muchos materiales como papel, vidrio, metales, plásticos, textiles y electrónicos. A veces el reciclaje no es posible y los materiales se reutilizan o usan para generar energía.
Este documento describe diferentes tipos de informes, incluyendo informes de calidad, desempeño, científicos, psicológicos, de lectura, académicos, ambientales y de ventas. Proporciona detalles sobre el propósito y contenido típico de cada tipo de informe.
INTERNAL CURING using Different admixtures- pdfAmrata Yadav
This document summarizes different internal curing methods for concrete including using artificial aggregates, drinking water treatment waste, and porous ceramic waste aggregate. It discusses the significance of these materials as internal curing agents and their effects on properties like compressive strength, porosity, and shrinkage of concrete. The document includes details on mixture proportions, material properties, and test results showing improved performance of concrete with internal curing.
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
Effect of Controlled Permeable Formwork on ConcreteIRJET Journal
This document summarizes research on the effect of controlled permeable formwork (CPF) on concrete properties. CPF is a formwork liner that allows air and excess water to drain from the concrete surface while retaining cement and fine particles. This improves the quality of the surface zone by reducing pores and increasing strength. The document reviews several studies that found CPF produced a denser, stronger surface zone with fewer defects, improved durability, and reduced water and chloride permeability compared to conventional impermeable formwork. CPF drains air and water migrating to the form due to vibration and pressure, resulting in a lower water-cement ratio and increased cement content in the surface zone.
Effect of Admixture on Properties of ConcreteIRJET Journal
This document discusses the effect of admixtures on the properties of concrete. It begins by defining concrete and its main components of cement, water, aggregates, and sometimes admixtures. It then discusses different types of admixtures including their physical and chemical functions. The document also examines how admixtures can be used to increase properties like strength and decrease weaknesses in concrete like brittleness. Finally, it analyzes how admixtures like silica fume can improve properties of lightweight concrete by increasing its strength.
A 36-year-old building collapsed in Bhiwandi, Thane, India at 3:40 am on September 21, 2020, killing 39 people. The building had 48 flats total, with 24 collapsing. The owner has been booked for culpable homicide and negligence. Building collapses are not uncommon in India, with over 13,000 structural collapses reported from 2010-2014 resulting in over 6,500 deaths. Concrete permeability and durability are important factors in preventing collapses. Permeability is influenced by water-cement ratio, compaction, and curing. The Indian code specifies minimum cement contents, water-cement ratios, and concrete grades required for different exposure conditions to ensure
Investigation Review of Self Curing Concrete Experiment ResultsIRJET Journal
This document summarizes an investigation into the physical properties of self-curing concrete using different admixtures. The study tested concrete with lightweight aggregates (LECA) ranging from 0-20% by volume and polyethylene glycol ranging from 1-3% by weight of cement. Tests measured volumetric water absorption, water permeability, water sorptivity, and mass loss at 28 days. Results showed LECA up to 15% and polyethylene glycol at 2% improved properties by retaining more moisture for hydration. Higher cement content, lower water-cement ratio, and addition of silica fume also improved durability. The study concluded self-curing agents along with silica fume can enhance physical properties of concrete compared to
This document summarizes a seminar report on bacterial concrete. It introduces the concept of using bacteria to self-heal cracks in concrete. Bacterial concrete is made by mixing dormant Bacillus subtilis bacteria and calcium lactate nutrients into the concrete. When cracks form and water enters, the bacteria spores germinate and metabolize the nutrients to precipitate calcite crystals that fill the cracks. Research shows bacterial concrete has lower permeability and increased strength compared to conventional concrete. It provides long-term self-healing without further human intervention that can extend the lifespan of concrete structures.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
An experimental study on durability of high strength self compacting concrete...eSAT Journals
Abstract The basic philosophy in the construction of every structure is it should perform its intended functions successfully through the expected and anticipated life time, irrespective of external exposure conditions. The ability of the concrete is to resist and withstand any environmental conditions that may result in early failure or severe damages and it is a major concern to the engineering professional. Out of all the deteriorating agents acid attack is one of the phenomena that plays a vital role in disintegrating concrete structures depending on the type and concentration of the acid. Certain acids are harmless. The present investigation focused on the effect of H2 So4 and HCL on High Strength Self Compacting Concrete. Keywords: Self Compacting Concrete, Durability, deterioration, Compressive strength, viscosity modifying agent, Workability
IRJET- Design of 300 Years Durable Concrete for Nuclear Confinement Zone ...IRJET Journal
This document discusses the design of a 300-year durable self-compacting concrete for use in nuclear confinement zones and tunnel formworks. The concrete mixture uses materials like cement, silica fume, Alccofine 1203, coarse aggregate, fine aggregate, and an admixture to achieve high durability and self-compaction properties. Silica fume and Alccofine help reduce carbonation and permeability through pozzolanic reactions and fine particle sizes. A water-binder ratio of 0.28 provides sufficient workability while ensuring complete hydration. This concrete is predicted to last 300 years based on durability modeling software.
IRJET- Behavior of Compound Concrete Filled Reinforced PVC Tubes Under Compre...IRJET Journal
This document discusses an experimental study on the compressive behavior of compound concrete filled reinforced polyvinyl chloride (PVC) tubes compared to unreinforced PVC tubes. Compound concrete contains a mixture of fresh concrete and demolished concrete lumps. Ten specimens were tested - two unreinforced and eight with internal steel stirrup reinforcement at varying spacings. Results showed that reinforced specimens had higher load capacity and compressive strength than unreinforced specimens. Closer stirrup spacing led to higher strength. Reinforcement improved the compressive performance of the composite tubes.
1) The document discusses using zeolite as a partial replacement for cement in concrete to reduce carbon dioxide emissions. Zeolite improves the properties of concrete such as compressive strength, carbon dioxide absorption, chloride permeability and expansion resistance.
2) Zeolite concrete can absorb up to 60% of the carbon dioxide released during the concrete production process, making it more environmentally friendly. The carbon dioxide absorption capacity of concrete increases by approximately 30% with the addition of zeolite.
3) Studies have found an optimal concentration of 10-20% zeolite replacement of cement to maximize compressive strength in concrete. Higher percentages may decrease strength. Zeolite concrete also exhibits greater resistance to chlorides and
IRJET- Experimental Study on the Behaviour of Self Healing Concrete using Sil...IRJET Journal
This document presents an experimental study on the behavior of self-healing concrete using silica gel in microcapsules as a healing agent. Concrete specimens were made with 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% dosages of silica gel by weight of cement. The specimens were initially cracked and then retested after 7 days of curing. Test results showed that specimens with 0.3% silica gel achieved the highest regain in compressive strength and split tensile strength after healing, reaching 55.34% of the original strength. The study aims to evaluate the influence of silica gel dosage on the strength properties of self-healing concrete.
Introduction of concrete
Historic development
Composition of concrete
Advantages of concrete over other materials
Advances and future trends in concrete
Overview of Sustainability and Concrete development.
IRJET- Environmental -Sustainable Solution of Pervious Concrete for PavementIRJET Journal
This document summarizes research on pervious concrete, which is a type of concrete with high permeability that allows water to pass through it. It discusses the composition and properties of pervious concrete, including its open pore structure, strength, permeability, and ability to reduce stormwater runoff. The document also reviews previous studies on pervious concrete that examined the effects of variables like the water-cement ratio on its properties. Applications of pervious concrete discussed include pavements, sidewalks, pools, and more. Benefits highlighted are reducing stormwater, recharging groundwater, lower costs, and increased safety.
AN EXPERIMENTAL INVESTIGATION ON EFFECT OF MECHANICAL PROPERTIES OF M50 GRADE...IRJET Journal
This document summarizes an experimental investigation on the effect of mechanical properties of M50 grade concrete with partial replacement of sand with copper slag. The study aims to determine the optimal percentage of polyethylene glycol (PEG-4000) to be added to self-curing concrete and examines how replacing sand with copper slag in various percentages affects the compressive strength, tensile strength, and flexural strength of the concrete mixes. Experimental results from previous studies on self-curing concrete and use of copper slag in concrete are discussed. The experimental procedure and materials used including cement, fine aggregate, coarse aggregate, water, PEG-4000, and copper slag are described.
IRJET - Variation of Cumulative Water Absorption in Concrete CubesIRJET Journal
This document summarizes research on the variation of cumulative water absorption in concrete cubes. It discusses how water absorption and permeability affect the durability of concrete structures. The researchers conducted experiments with 72 concrete cubes containing different concrete mixtures to evaluate the effectiveness of cumulative water absorption. The results showed that cumulative water absorption decreases with decreasing water absorption and increases with increasing water absorption rate. Cumulative absorption also decreases with increasing aggregate content and compressive strength but increases with higher water-cement ratios and over time. The sorptivity coefficient, which indicates water penetration rate, decreases with higher compressive strength and cumulative absorption.
A Study on Properties of Self Compacting Concrete with Slag as Coarse AggregateIRJET Journal
This document presents a study on the properties of self-compacting concrete using blast furnace slag as a coarse aggregate replacement. The study aims to determine the strength characteristics of slag for application in self-compacting concrete. Specimens with 0%, 10%, 20%, 40%, and 60% replacement of natural coarse aggregate with slag aggregate were produced and tested. Workability, compressive strength, and split tensile strength tests were conducted on the specimens. The results were then compared to code requirements to evaluate the performance of self-compacting concrete with slag aggregate replacement.
EFFECT OF POLYCARBOXYLATE ON COMPRESSIVE STRENGTH OF PERVIOUS CONCRETEIAEME Publication
This document discusses the effects of adding polycarboxylate to pervious concrete mixes on compressive strength. Pervious concrete is a porous pavement that allows water to drain through it. The study tested pervious concrete mixes with 10mm and 11.2mm aggregates and varying amounts of polycarboxylate additive from 2-6 ml. Compressive strengths were tested at 7 and 28 days. Results showed compressive strength generally increased with polycarboxylate content, with highest strengths at 5 ml for both aggregate sizes and curing periods. The chemical reaction between polycarboxylate and cement was concluded to increase compressive strength. Usage of pervious concrete with polycarboxylate was found to meet strength
Similar to Chapter 2 seviceability and durability (20)
This document discusses groundwater hydrology. It defines groundwater as water located beneath the earth's surface, filling the pore spaces of sediment and cracks in rock. Groundwater exists in two zones - the unsaturated zone above the water table, and the saturated zone below it. The saturated zone can be classified as aquifers, which transmit groundwater; aquicludes, which do not transmit water; aquifuges, which transmit no water; and aquitards, which transmit water slowly. Properties like porosity, permeability, and transmissibility determine an aquifer's ability to store and transport groundwater according to Darcy's Law.
Module 2 ch-1 heytograph and hydrology analysisAnkit Patel
This document discusses hyetographs, hydrographs, runoff, and unit hydrographs. It contains the following key points:
1. A hyetograph is a graphical representation of rainfall intensity over time, showing the relationship between rainfall amount and time. A hydrograph shows stream discharge over time.
2. Runoff is the portion of rainfall that flows into streams and rivers. It is affected by rainfall characteristics and basin properties like soil, vegetation and topography.
3. A unit hydrograph represents the runoff from 1 cm of effective rainfall uniformly distributed over a basin and duration. It can be used to estimate flood hydrographs from storm rainfall amounts and distributions.
The document discusses hydrology and the hydrologic cycle. It begins by defining hydrology as the science of water and its movement on the Earth. It then describes the key components of the hydrologic cycle, including evaporation, precipitation, infiltration, transpiration, and the various stages water passes through as it circulates from the oceans to the atmosphere and back again. Engineering applications of hydrology are also mentioned such as flood control and selecting dam sites. Measurement of rainfall is discussed, along with different types of rain gauges used to collect precipitation data.
Traffic studies are carried out to analyze traffic characteristics and help decide geometric design and traffic control measures. The main traffic studies include traffic volume, speed, origin-destination, traffic flow characteristics, capacity, and accident studies. Traffic volume studies measure the number of vehicles on a road section over time and are used for planning, operations, and analysis. Speed studies measure the speeds of vehicles using methods like short-distance timing or radar guns.
This document discusses traffic characteristics and engineering. It defines traffic engineering as dealing with planning and designing streets and highways for safe, efficient traffic flow. Road users and their physical, mental, psychological characteristics are examined, as well as vehicles' static properties like weight and dimensions, and dynamic properties like speed and braking. Traffic surveys study these characteristics to determine road geometry and controls. Perception, intellect, emotion and volition times that make up a driver's total reaction time are also outlined.
This document discusses the demolition of structures. It outlines the objectives, planning steps, safety measures, and methods used for demolition. Surveys are conducted to identify hazardous materials and structural details. A demolition plan is then prepared outlining the sequence, equipment, and safety procedures. Common demolition methods include mechanical techniques like wrecking balls, hydraulic breakers, and dismantling, as well as explosives for implosions. Factors like the structure type and location influence the chosen method.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
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.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
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
2. Durability
Durability of Portland cement is defined as its ability to resist weathering
action, chemical attack, abrasion or any other process of deterioration that is
durable concrete will retain its original form, quality, and serviceability when
expose to its environment. It is generally accepted now that in designing
structures the durability characteristics of materials under consideration
should be evaluated as carefully as other factors. The durability of concrete
depends on its resistance to deterioration and the environment in which it is
placed. The resistance of concrete to weathering, chemical attack, abrasion,
frost and fire depends largely upon its quality and constituent materials. All
concrete in service will be subject to chemical and physical changes. A
durable concrete is one in which these changes occur at a rate, which does not
detrimentally affect its performance within its intended life. Leave it to
concrete alone, the material remains by and large durable, but concrete alone
cannot be utilised extensively for structural applications. It is the Reinforced
Concrete (RCC), a composite structural material, which is utilised for variety
of structural uses.BITS Edu Campus Prof. Ankit Patel 2
3. Durability
But, it has been observed that RCC has not proved to be durable due to large
number of factors, including variations in production, loading conditions in
service life and subsequent attack by the environmental factors. However, a
well constituted, properly compacted, and cured concrete used in RCC
continues to be substantially water tight and durable as long as capillary pores
and micro-cracks in the interior do not become interconnected pathways
leading to surface of concrete. Based on this simplification of causes, few
holistic models of deterioration of RCC have been illustrated, which represent
a qualitative design approach for easy understanding of the contributing
factors for deterioration and its mechanism.
BITS Edu Campus Prof. Ankit Patel 3
17. Holistic Model of Deterioration of RCC
Model-1:
According to this holistic model of deterioration of concrete shown in Fig,
the deterioration process is considered in two stages. During the first stage,
due to loading and weathering effects (e.g. cycles of wetting & drying,
seasonal temperature variations, etc) the voids and micro-cracks in the
interfacial zone between the cement paste and coarse aggregate or
reinforcing steel become inter-linked. When the inter-linked network of
micro-cracks gets connected to any cracks present at the concrete surface,
this provides the primary mechanism of fluid transport into the interior of
concrete. Once this happens, the penetrability of concrete increases greatly
and the beginning of the second stage during which water, oxygen, carbon
dioxide and acidic ions are able to penetrate easily into concrete. The
presence of these elements facilitates various physical-chemical interactions
as a result of which, the material eventually undergoes cracking, spalling
and loss of mass resulting in partial loss of strength and stiffness
BITS Edu Campus Prof. Ankit Patel 17
19. Holistic Model of Deterioration of RCC
Model-2:
According to this concept as illustrated in Fig there are three stages, namely
gradual loss of water tightness, initiation of damage and propagation of
damage. During the stage 1 no noticeable weakening of the material occurs
but some protective barrier is being broken down, such as the depassivation
of the reinforcing steel by CO2 or chloride penetration
BITS Edu Campus Prof. Ankit Patel 19
20. Holistic Model of Deterioration of RCC
Module-3:
Another model on deterioration of concrete, which is dependent on the
important role played by water cement ratio (W/C), is illustrated in Fig. This
offers an overall view on the Co-existence of the following three principal
elements.
(a) Interconnected porosity of Cement paste
(b) Exposure to aggressive agents/chemicals
(c) Intermittent presence of water
In absence of any of these three elements, damage to RCC will not occur.
For example, even in a porous and/or micro cracked concrete, further
deterioration cannot occur, in absence of Water/moisture even if there is a
potential presence of environmental aggressive agent such as SO4, Cl- , and
CO2. In absence of water/moisture, these aggressive ions cannot travel,
through inter connected pores. Thus, neither sulphate attack on cement paste
nor the corrosion of steel reinforcement can occur.
BITS Edu Campus Prof. Ankit Patel 20
21. Holistic Model of Deterioration of RCC
BITS Edu Campus Prof. Ankit Patel 21
30. Fresh concrete contains a considerable quantity of free water. If such
concrete subject to freezing temp, discrete ice lenses are formed. Water
expands about 9% in volume during freezing, so that the excess water in
the cavity is expelled. The formation of ice lenses formed in the body of
fresh concrete disrupt the fresh concrete causing nearly permanent
damage to concrete. Such concrete will not recover the structural
integrity, if later on allowed to harden at temp higher than the freezing
temp.
For fully hardened concrete subjected to alternate cycles of freezing and
thawing the Servest conditions for frost action arise when concrete has
more than one face expose to the weather and it remains wet for longer
period. For example parapets, road kerb etc has been estimated that the
freezing of water in hardened concrete may exert pressure of about
14Mpa. If the hydraulic pressure so generated exceeds the tensile strength
of the concrete, cracks are developed in concrete.
Freezing starts at the surface in the largest cavities and gradually extends
to smaller ones. Gel pores are too small to get it frozen till the temp goes
below -78 degree Celsius so that in practice no ice is formed in gel pores.
BITS Edu Campus Prof. Ankit Patel 30
31. Rate of freeze-thaw deterioration:
Increase porosity increase rate
Increase moisture saturation increase rate
Increase number of freeze cycle increase rate
Air entrainment decrease rate
Preventive measures:
Use of lowest practical w/c ratio
Adequate air entrainment
Use of durable non porous aggregate
Adequate curing of concrete prior to exposure to freezing and
thawing
Providing proper drainage rather than flat surfaces.
BITS Edu Campus Prof. Ankit Patel 31
34. Sea water contains 3.5 percent of salt by weight. Its PH value varies
between 7.5 to 8.4. sea water also contains some amount of C02.
Concrete between the tide marks subjected to alternating weeting &
drying is severely attacked , while permanently immerse concrete is
attacked least.
It is therefore necessary to provide a sufficient cover to reinforcement
preferably 75mm.
BITS Edu Campus Prof. Ankit Patel 34
39. Carbonation
The carbon dioxide present in atmosphere reacts in the presence of water
with hydrated cement minerals, converting calcium hydroxide to calcium
carbonate. The carbonation penetrates beyond the exposed surface of
concrete only very slowly.
The important factor affecting rate of carbonation are:
Grade of concrete
Relative humidity
Permeability of concrete
Cover of reinforcement
Time
In case of stronger concrete the rate of carbonation depth will be slower. The
permeability of concrete also affects the rate carbonation. In permeable
concrete carbonation penetrate at a faster rate, than in dense concrete.
Concrete with higher w/c ratio is more susceptible to carbonation. The depth
of carbonation can be measured by treating the freshly broken surface of
concrete with a solution of phenolphthalein in diluted alcohol.BITS Edu Campus Prof. Ankit Patel 39
40. Carbonation
Concrete of good quality usually carbonates very slowly. Even after a period
of 50 years carbonation is to penetrate to a depth of about 5 to 10mm. On
the other hand a permeable concrete may carbonate to depth of 25mm in
less than 10 years.
Carbonation reduced due to reduced moisture content and reduced carbon
dioxide concentration in the atmosphere.
BITS Edu Campus Prof. Ankit Patel 40
55. Alkali Aggregate Reaction (AAR)
The alkali silica gel formed by alkali aggregate reaction is confined by the
surrounding cement paste and internal pressure is developed leading to
expansion , cracking and disruption of cement paste. The reactivity of
aggregate depends upon its particle size and porosity as these influences the
area over which the reaction takes place
Factors Promoting the alkali aggregate reactions:
Reactive type of aggregate
High alkali content in cement
Optimum temperature
Availability of moisture
Measures to control alkali aggregate reactions:
Selection of non reactive types of aggregates
By restricting alkali content in cement below 0.6%
By controlling temp
By controlling moisture conditions
By the use of corrective admixtures such as pozzolonas
By controlling the void space in concreteBITS Edu Campus Prof. Ankit Patel 55
57. Sulphate Attack
The sulphate of calcium, sodium, potassium, and magnesium are present in
most soils and ground water. Agricultural soil and water contains
ammonium sulphate from the use fertilizers or from sewage and industrial
effluents. Water use in concrete cooling towers can also be a potential
source of sulphate attack.
Solid salt do not attack concrete, but when present in solution they can react
with hardened cement paste. In hardened concrete, sulphate react with the
free calcium hydroxide to form calcium sulphate. Similarly sulphate react
with calcium aluminate hydrate (C-A-H) to form calcium sulphoaluminate.
The produce of the reactions, gypsum and calcium sulphoaluminate have a
considerably greater volume than the compound they replace, so that the
reactions with the sulphate lead to expansion and disruption of the concrete .
Of all the sulphate, magnesium sulphate causes maximum damage to
concrete.
With increase in the strength of the solution the rate of sulphate attack
increases. But beyond a concentration of about 0.5 % of MGSO4 the rate of
increase in the intensity of the attack becomes smaller.BITS Edu Campus Prof. Ankit Patel 57
58. Sulphate Attack
Attack of magnesium sulphate to concrete with higher w/c ratio can causes
serious damage to concrete. If concrete is made with low water cement ratio
the concrete can withstand the action of magnesium sulphate for 2 to 3
years. In addition to the concentration of the sulphate, the speed with which
concrete is attacked also influences the rate of sulphate attack. When
concrete is exposed to the pressure of sulphate bearing water on one side the
rate of attack will be highest.
Methods for controlling sulphate attack:
Use of sulphate resisting cement
Addition of pozzolana
Quality of concrete
Use of air entrainment
Use of high alumina cement
BITS Edu Campus Prof. Ankit Patel 58
61. Acid Attack
Concrete is used for the storage of many kinds of liquids, some of
which are harmful to concrete. In industrial plants, concrete floors
come in contact with acids which damage the floor. In damp condition
SO2 and CO2 and other acid fumes present in atmosphere affect
concrete by dissolving and removing part of the set concrete. The
form of attack occurs in chimney and steam railway tunnels. In fact
no Portland cement is acid resistant.
Acid attack is encounter also under industrial conditions. Concrete is
also attacked by water containing free CO2.
In practice, acid attack occurs at values of PH below about 6.5. but
the attack is serve only at a PH value below 5.5. At a PH value below
4.5, the attack is serve. Under acid attack, cement compounds are
eventually broken down and leached away. If acids or salts are able to
reach the reinforcing steel through cracks or porosity of concrete,
corrosion of reinforcement take place.BITS Edu Campus Prof. Ankit Patel 61
62. Efflorescence
Efflorescence, a deposit of salts on concrete surfaces, can decorate the
surfaces with a new color scheme that probably won’t please the
architect or owner of a structure. It causes unsightly white stains,
usually near cracks or joints where water passes through concrete.
There are effective methods for controlling efflorescence and, if it
occurs, removing it.
BITS Edu Campus Prof. Ankit Patel 62
63. Efflorescence
We know that efflorescence is a fine, white, powdery deposit of
water-soluble salts left on the surface of masonry as the water
evaporates. These efflorescent salt deposits tend to appear at the worst
times, usually about a month after the building is constructed, and
sometimes as long as a year after completion. Efflorescence is not a
simple subject.
Three conditions must exist before efflorescence will occur.
• First: There must be water-soluble salts present somewhere in the
wall.
• Second: There must be sufficient moisture in the wall to render the
salts into a soluble solution.
• Third: There must be a path for the soluble salts to migrate through
to the surface where the moisture can evaporate, thus depositing the
salts which then crystallize and cause efflorescence.
All three conditions must exist. If any one of these conditions is not
present, then efflorescence cannot occur.
BITS Edu Campus Prof. Ankit Patel 63
64. Efflorescence
The efflorescence process:
Concrete structures endure a continuous moisture cycle of wetting
and drying. Water from rain, snow, groundwater, or condensation
enters the concrete. As it moves through the concrete, the water
dissolves soluble compounds, bringing them in solution to the surface
where they are deposited when the water evaporates. The availability
of water, permeability of the concrete, and amounts of soluble
compounds determine how much efflorescence will occur and when it
will stop. Water temperature and hardness also have an effect Calcium
hydroxide, a water-soluble cement hydration product, is the most
common source of efflorescence. A cubic yard of concrete contains
from 100 to 150 pounds of calcium hydroxide. Other alkalies are
present in the concrete but when these highly soluble alkaline
compounds come to the surface they’re washed away by rain
BITS Edu Campus Prof. Ankit Patel 64
65. Efflorescence
Controlling efflorescence :
There are three ways to control efflorescence: reduce water flow
through the concrete, reduce the amount of salt that’s contained in
mix ingredients, or convert soluble compounds to an insoluble form
Removing efflorescence:
Calcium hydroxide remains soluble for only a brief time after
reaching the concrete surface. When exposed to carbon dioxide in the
atmosphere it converts to calcium carbonate, which is difficult to
dissolve. Consequently, it pays to try to remove efflorescence
promptly while the salt deposits can still be washed off with water
alone. This avoids working with acids that might etch the concrete
and damage adjacent materials
BITS Edu Campus Prof. Ankit Patel 65
66. Efflorescence
Any of several diluted solutions of acids are effective ways to remove
eff l o r e s c e n c e :
one part hydrochloric acid in nine to 19 parts water
one part phosphoric acid in nine parts water
one part phosphoric acid plus one part acetic acid in 19 parts water
Good drainage also helps prevent efflorescence
Use a low water-cement ratio and adequate curing to reduce the
amount of water passing through pores in the concrete.
Using an integral w a t e r-repellent or waterproofed will also
reportedly reduce water movement through the concrete
For existing concrete, clear coatings or sealers decrease moisture
absorption. This reduces the amount of efflorescence caused by
wetting-and drying cycles.
BITS Edu Campus Prof. Ankit Patel 66
67. Thermal properties of concrete
The important thermal properties of concrete required for design of
structures:
Thermal conductivity
Thermal diffusivity
Specific heat
Coefficient of thermal expansion
Thermal conductivity:
It is a measure of the ability of the concrete to conduct heat. It is
defined as the ratio of flux of heat to temp gradient.it is measure in
J/m2
The conductivity of ordinary concrete depends on its composition and
when concrete is saturated the conductivity ranges generally from 1.4
to 3.6 J/m2.
Conductivity of concrete depends on types of aggregate moisture
content density of concrete and temp of concrete.BITS Edu Campus Prof. Ankit Patel 67
68. Thermal diffusivity:
It is a measure of the rate at which temp changes within the mass
takes place.
Diffusivity =Conductivity / CP
‡where C is the specific heat, and P is the
density of concrete.
Specific Heat:
It is defined as the quantity of heat required to raise the temp of a unit
mass of concrete by 1 degree Celsius.
Specific heat gets increase with an increase in temp.
Coefficient of thermal expansion:
It is defined as the change in length per degree change in temp.
It depends upon the composition mix coefficient of expansion of
cement paste coefficient of expansion of aggregate.
An average value of the linear thermal coefficient of
expansion of concrete may be taken as 9.9 x 10±6 per °C
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70. Permeability of concrete
The transport of fluid through concrete depends on structure of the
hydrated cement paste. The flow of fluid through concrete is
referred as permeability. Permeability (Interconnected porosity) is
related to :
Capillary Porosity
Air voids
Micro cracks
Macro cracks
1. Capillary porosity: it has been estimated that about 23% of water
by weight of cement is required for chemical reaction. However for
achieving full hydration excess of water is required. This extra
volume of water entrapped in the cement paste after completion of
hydration leaves interconnected pores called capillaries in hardened
concrete which becomes means of passage for external chemicals into
the concrete. This porosity is termed as capillary porosity.BITS Edu Campus Prof. Ankit Patel 70
71. Permeability of concrete
2.Air voids: it is formed due to inadequate compaction in the form of
discrete air bubbles of much larger size than capillary pores. These air
voids may get interconnected by capillary pore system, leading to
permeability of concrete.
3. Micro Cracks: reinforced concrete structure are subjected to various
types of loading conditions ie static loading , cyclic loading, impact
loading during its service life. These structures are also exposed to
extreme conditions of temp changes. These varying loading condition
and exposure condition cause micro cracking in concrete. Micro
cracking combined with capillary pores is generally responsible for
ingress of aggressive chemicals in concrete.
4. Macro cracks: Any crack width, which allows aggressive chemicals
to travel freely into the concrete is termed as macro cracks.
Causes of micro cracks is due to improper placement of concrete,
settlement cracks of fresh concrete, alkali aggregate reaction, heat of
hydration, inc volume of corroded reinforcement and excessive loading.
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80. Causes of Corrosion & Remedial Measures
1. Presence of cracks in concrete: Certain amount of cracking always
occurs in the tension zone of RCC depending upon the stresses in the
reinforcing steel. Through these cracks, oxygen or sea water ingress
into the concrete and set up a good environment for corrosion of
reinforcement.
2. Presence of moisture: Presence of moisture is a precondition for
corrosion to take place because concrete can act as electrolyte in
electrochemical cell only if it contains some moisture in pores.
Corrosion can neither occur in dry concrete nor in submerged
concrete. The worst combination for corrosion to proceed is when
the concrete is slightly drier than saturated about 8-9% relative
humidity with low resistivity and the oxygen can still penetrate to the
steel. Hence in high humidity areas like coastal India, low
permeability concrete is recommended.
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81. Causes of Corrosion & Remedial Measures
3. Permeability of concrete: this is also an important factor affecting
corrosion of reinforcement. Ingress of moisture, sea water, oxygen,
carbon dioxide is easier in porous concrete than in dense and
impermeable concrete. It is worth mentioning that with each increases of
W/C ratio of 0.1 permeability of concrete increases 1.5 times. Poor
curing increases permeability 5 to 10 times in comparison to good cured
concrete and poor compaction increases permeability 7 to 10 times in
comparison to good compacted concrete. Therefore quantity of cement
in concrete should not be less than 350 kg/m3. and w/c ratio should not
exceed 0.55 for ordinary structures and 0.45 for marine structures.
4. Carbonation
5. Chloride
6. Sulphate Attack
7. Alkali aggregate reaction
8. Inadequacy of cover
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82. Difference between porosity and
permeability of Concrete
The main difference between porosity and permeability is
that porosity is a measurement of space between
rocks whereas permeability is a measurement of how easy it is
for fluids to flow between rocks.
Porosity and permeability are two distinct physical properties of
solids. Porosity refers to the extent to which tiny pores or spaces
exist within the solid. Permeability refers to the ability of a mass of
solid to allow or restrain the passage of of fluids, that is gases or
liquids, through itself. These two qualities are closely related. The
fluids are able to permeate through a solid by passing through the
pores it contains, and grater the number and size of pores in a given
mass of solid, easier it is for the fluids to pas through. Thus in
general higher porosity in a material is likely to be accompanied by
higher permeability also.
Porosity is a ratio of volumes, so it has no units.
Permeability has (m /s in the SI system).
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83. REALKALISATION
Realkalisation is a method used to stop and permanently prevent
reinforcement corrosion in carbonated concrete structures by increasing
their pH to a value greater than 10.5, which is sufficient to restore and
maintain a passive oxide film on the steel. Realkalisation involves a
technique whereby a current is passed through the concrete to the
reinforcement by means of an externally applied anode, which is attached
temporarily to the concrete surface. A paste of sprayed cellulous fibre with a
solution of potassium or sodium carbonate is used as the electrolyte
covering the concrete surface.
The net effect of realkalisation includes it's effect on the concrete and on the
steel reinforcement. The alkaline solution is transported into the concrete
mass under the influence of the low voltage electrical current. This raises
the concrete pH level to greater than 10.5. With regard to the effect on steel
reinforcement, the alkalinity is increased at the steel surface by production
of hydroxyl ions. This reinstates the dense passive film on the steel, which
protects from further corrosion.
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84. REALKALISATION
The realkalisation process requires minimal repair work of the concrete,
especially the need to break out concrete behind the reinforcement, which is
in itself a noisy, and expensive exercise. The realkalisation process takes
approximately one week to complete.
Key features of this technology are:
Environmentally friendly: Major reduction of concrete breakout.
Low maintenance: In comparison to patch repair and coating.
Long term global protection: Provides effective treatment for the entire area
of application.
Proven technology: Long history of satisfactory performance.
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