Effect of curing: conditions on strength and durability of high-performance concrete
Canpolat F. , Naık T. R.
SCIENTIA IRANICA, Vol.24, ss.576-583, 2017
DOI: 10.24200/sci.2017.2419
This paper describes the effects of variable curing temperatures on compressive strength and sulfate resistance of high-strength, high-performance concrete. Two different concrete mixtures were proportioned to attain the 56-day compressive strength of about 70 MPa upon moist-curing. One mixture contained more quantity of ASTM Class C fly ash than the other one. For each mixture, one set of specimens was cured in a standard moist-curing room at 23 degrees C and 100% relative humidity; another set of specimens was sealed in plastic bags and cured in an elevated, Variable-Temperature Curing Environment (VTCE). The average temperature of the VTCE oscillated between about 30 C and 41 C once per day. This study revealed that the VTCE-cured concrete did not significantly exhibit different compressive strength or ability to resist sulfates attack compared to the standard moist-cured specimens. Thus, it was concluded, based on the results of this research, that additional effort to stabilize higher curing-temperatures would be necessary for field-cured concrete
Experimental evaluation of the durability properties of high performanceIAEME Publication
The document discusses the use of admixtures to improve the durability properties of high performance concrete (HPC). It describes how supplementary cementing materials (SCMs) like fly ash, silica fume, and metakaoline can improve the strength and durability of HPC when used to partially replace cement. The document also examines the acid resistance and sulfate resistance of HPC specimens containing these admixtures through immersion testing in acid and sulfate solutions. Test results showed that HPC with SCMs exhibited greater resistance to chemical attacks compared to plain cement concrete.
Experimental evaluation of the durability properties of high performanceIAEME Publication
The document discusses the use of admixtures to improve the durability properties of high performance concrete (HPC). It describes how supplementary cementing materials (SCMs) like fly ash, silica fume, and metakaoline can improve the strength and durability of HPC when used to partially replace cement. The document also examines the acid resistance and sulfate resistance of HPC mixtures containing various SCMs through experimental testing of specimens exposed to acids and sulfate solutions.
Metamodel techniques to estimate the compressive strength of UHPFRC using var...Shakerqaidi
This document discusses the development of metamodel techniques to estimate the compressive strength of ultra-high performance fiber reinforced concrete (UHPFRC) based on mix proportions and curing temperatures. Four soft computing techniques were developed: nonlinear relationship model, pure quadratic model, M5P-tree model, and artificial neural network model. The artificial neural network model performed best with the lowest error and highest accuracy based on 274 data points analyzing the effect of 11 variables on compressive strength, including curing temperature. The most influential variables were found to be curing temperature, fiber content, and curing time.
Strength and durability studies on silica fume modified high volume fly ash c...IAEME Publication
This document discusses a study on the strength and durability of silica fume modified high-volume fly ash concrete. Five concrete mixes were tested: a control mix and four mixes where 50% of cement was replaced with fly ash and additional replacement of cement with 5%, 10%, and 15% silica fume. Testing included compressive strength at various ages, rapid chloride permeability, chloride ion diffusion, and carbonation resistance. The addition of silica fume to high-volume fly ash concrete was found to improve mechanical properties and durability compared to fly ash concrete without silica fume.
This document summarizes a study on the effects of elevated temperatures on the compressive and splitting tensile strengths of ultra-high strength concrete. Cubes and cylinders of M100 grade concrete were exposed to temperatures between 50-250°C for durations of 1-4 hours. Testing found that compressive and splitting tensile strengths initially increased with temperature up to 100°C but then decreased with further increases in temperature. The maximum strengths were observed when specimens were heated to 100°C for 1 hour. Understanding how high-strength concrete properties change after fire exposure can help determine the load capacity of damaged structures.
RESIDUAL COMPRESSIVE STRENGTH OF TERNARY BLENDED CONCRETE AT ELEVATED TEMPERA...Ijripublishers Ijri
The extensive use of concrete as a structural material for the high rise buildings, storage tanks, nuclear reactors and
pressure vessels increase the risk of concrete being exposed to high temperatures. This has led to a demand to improve
the understanding of the effect of temperature on concrete. The behavior of concrete exposed to high temperature is a
result of many factors including the exposed environment and constituent materials.
Concrete structures are exposed to fire when a fire accident occurs. Damage in concrete structures due to fire depends
to a great extent on the intensity and duration of fire. The distress in the concrete manifests in the form of cracking and
spalling of the concrete surface.
In general, Developing and maintaining world’s facilities to meet the future needs have developing to improve the total well-being. The standard and performance of concrete perform a critical role for most of the facilities including commercial, industrial, and residential and army, public works, and power plants. Concrete sets as the solid hydrates, and is an exothermic response, means it produces heat response goes quickly when the concrete is a hot condition. The primary reason for the concrete's strength and setting time is not the air temperature range but the particular heat range. Varying climate circumstances at a work site cold and hot, windy or relaxed, dry or moist may be considerably different from the best possible conditions believed at sufficient time a concrete mix is specified designed, or selected, or from lab circumstances in which concrete samples are saved and tested. This paper provides the results of a study performed to look at the condition of concrete in hot and cold weather in the construction industry under the climate of Afghanistan.
This document summarizes a study on rehabilitation techniques for existing concrete structures. It discusses various repair methods and materials that can be used, including polymer modified mortar. Non-destructive tests were conducted on a sample structure to evaluate its condition. Based on the results, polymer modified mortar was selected for repairing columns due to its low cost, ease of application, and ability to extend the life of the building for 15-18 years at a lower cost than reconstruction. The study concludes that repairing existing structures using appropriate technologies and materials is more economical than demolition and aims to provide guidance on cost-effective rehabilitation.
Experimental evaluation of the durability properties of high performanceIAEME Publication
The document discusses the use of admixtures to improve the durability properties of high performance concrete (HPC). It describes how supplementary cementing materials (SCMs) like fly ash, silica fume, and metakaoline can improve the strength and durability of HPC when used to partially replace cement. The document also examines the acid resistance and sulfate resistance of HPC specimens containing these admixtures through immersion testing in acid and sulfate solutions. Test results showed that HPC with SCMs exhibited greater resistance to chemical attacks compared to plain cement concrete.
Experimental evaluation of the durability properties of high performanceIAEME Publication
The document discusses the use of admixtures to improve the durability properties of high performance concrete (HPC). It describes how supplementary cementing materials (SCMs) like fly ash, silica fume, and metakaoline can improve the strength and durability of HPC when used to partially replace cement. The document also examines the acid resistance and sulfate resistance of HPC mixtures containing various SCMs through experimental testing of specimens exposed to acids and sulfate solutions.
Metamodel techniques to estimate the compressive strength of UHPFRC using var...Shakerqaidi
This document discusses the development of metamodel techniques to estimate the compressive strength of ultra-high performance fiber reinforced concrete (UHPFRC) based on mix proportions and curing temperatures. Four soft computing techniques were developed: nonlinear relationship model, pure quadratic model, M5P-tree model, and artificial neural network model. The artificial neural network model performed best with the lowest error and highest accuracy based on 274 data points analyzing the effect of 11 variables on compressive strength, including curing temperature. The most influential variables were found to be curing temperature, fiber content, and curing time.
Strength and durability studies on silica fume modified high volume fly ash c...IAEME Publication
This document discusses a study on the strength and durability of silica fume modified high-volume fly ash concrete. Five concrete mixes were tested: a control mix and four mixes where 50% of cement was replaced with fly ash and additional replacement of cement with 5%, 10%, and 15% silica fume. Testing included compressive strength at various ages, rapid chloride permeability, chloride ion diffusion, and carbonation resistance. The addition of silica fume to high-volume fly ash concrete was found to improve mechanical properties and durability compared to fly ash concrete without silica fume.
This document summarizes a study on the effects of elevated temperatures on the compressive and splitting tensile strengths of ultra-high strength concrete. Cubes and cylinders of M100 grade concrete were exposed to temperatures between 50-250°C for durations of 1-4 hours. Testing found that compressive and splitting tensile strengths initially increased with temperature up to 100°C but then decreased with further increases in temperature. The maximum strengths were observed when specimens were heated to 100°C for 1 hour. Understanding how high-strength concrete properties change after fire exposure can help determine the load capacity of damaged structures.
RESIDUAL COMPRESSIVE STRENGTH OF TERNARY BLENDED CONCRETE AT ELEVATED TEMPERA...Ijripublishers Ijri
The extensive use of concrete as a structural material for the high rise buildings, storage tanks, nuclear reactors and
pressure vessels increase the risk of concrete being exposed to high temperatures. This has led to a demand to improve
the understanding of the effect of temperature on concrete. The behavior of concrete exposed to high temperature is a
result of many factors including the exposed environment and constituent materials.
Concrete structures are exposed to fire when a fire accident occurs. Damage in concrete structures due to fire depends
to a great extent on the intensity and duration of fire. The distress in the concrete manifests in the form of cracking and
spalling of the concrete surface.
In general, Developing and maintaining world’s facilities to meet the future needs have developing to improve the total well-being. The standard and performance of concrete perform a critical role for most of the facilities including commercial, industrial, and residential and army, public works, and power plants. Concrete sets as the solid hydrates, and is an exothermic response, means it produces heat response goes quickly when the concrete is a hot condition. The primary reason for the concrete's strength and setting time is not the air temperature range but the particular heat range. Varying climate circumstances at a work site cold and hot, windy or relaxed, dry or moist may be considerably different from the best possible conditions believed at sufficient time a concrete mix is specified designed, or selected, or from lab circumstances in which concrete samples are saved and tested. This paper provides the results of a study performed to look at the condition of concrete in hot and cold weather in the construction industry under the climate of Afghanistan.
This document summarizes a study on rehabilitation techniques for existing concrete structures. It discusses various repair methods and materials that can be used, including polymer modified mortar. Non-destructive tests were conducted on a sample structure to evaluate its condition. Based on the results, polymer modified mortar was selected for repairing columns due to its low cost, ease of application, and ability to extend the life of the building for 15-18 years at a lower cost than reconstruction. The study concludes that repairing existing structures using appropriate technologies and materials is more economical than demolition and aims to provide guidance on cost-effective rehabilitation.
Concrete is a composite material made of coarse aggregate bonded together with a fluid cement that hardens over time. The document discusses properties of both fresh and hardened concrete, including workability, strength, permeability, durability, response to temperature changes, and causes of damage. It provides definitions of key terms, describes tests used to evaluate properties like slump and compressive strength, and explains factors that affect the durability of concrete such as permeability, sulfate attack, freezing and thawing, and corrosion of reinforcing steel.
Flexural Behavior of Fibrous Reinforced Cement Concrete Blended With Fly Ash ...Ijripublishers Ijri
This document discusses high strength concrete that is reinforced with fibers. It provides background on concrete composites and describes how high strength concrete is achieved through methods like using a lower water-cement ratio or supplementary cementitious materials. The document focuses on fiber reinforced concrete and the benefits fibers provide, such as improved strength and crack resistance. It also discusses different types of fibers like steel fibers and their properties. Blended cements and use of pozzolanic materials like metakaolin and fly ash are described as ways to further improve concrete strength and durability.
Development of high-strength, economical self-consolidating concretePubl 2022
Naık T. R. , Kumar R., Ramme B. W. , Canpolat F.
This paper presents information regarding development, properties, and advantages and disadvantages of using high-strength self-consolidating concrete in the construction industry. It also presents results of a study recently completed for manufacturing economical high-strength self-consolidating concrete containing high-volumes of fly ash. In this study, portland cement was replaced by Class C fly ash in the range of 35-55% by the mass of cement. The results of fresh and hardened properties of concrete show that the use of high-volumes of Class C fly ash in self-consolidating concrete reduces the requirements for superplasticizer (HRWRA) and viscosity modifying agent (VMA) compared with the normal dosage for such admixtures in self-Consolidating concrete. The results further indicate that economical self-consolidating concrete with 28-day strengths up to 62 MPa can be made using high-volumes of fly ash. Such concretes can be used for a wide range of applications from cast-in-place to precast concrete construction.
DOI:10.1016/j.conbuildmat.2011.12.025
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.
Study of Compressive and Flexural Strength of Fibrous Triple Blended High Str...researchinventy
-Change has been a constant parameter within the concrete industry in view of increasing construction activities and most importantly an increased thrust in high quality yet economic structures. This change has thus, brought along with it, different trends in concrete technology with respect to the way in which it is perceived and more technically, its composition, its handling, mixing etc. . As a result, we have today, different types of concretes such as triple blended concrete, self-compacted concrete, bacterial concrete etc. which have, in their own respective manner, succeeded in enhancing the serviceability of the structure with which they are built, in comparison to ordinary concrete. In this report, we focus and emphasize on Triple Blended Concrete, its meaning, materials involved, process of casting, testing, salient features et al.
This document discusses self-compacting concrete (SCC), which is a type of concrete that can flow and consolidate under its own weight without any external vibration. SCC has advantages over traditional vibrated concrete such as easier placement in complex forms, reduced noise pollution, and improved surface finish. The key properties of SCC include high flowability, passing ability, and segregation resistance. These properties are achieved through optimizing the mix design, including using a high range of superplasticizer, limiting coarse aggregate content, increasing fine particles and viscosity modifying agents. SCC has applications in structures with dense reinforcement like the Burj Khalifa where it simplified construction. The document also discusses experimental investigations into the compressive strength of SCC exposed to
Evaluation of Saturated Conditioned Concrete Cubes by Initial Surface Absorpt...IRJET Journal
This document presents research on evaluating saturated concrete cubes using an Initial Surface Absorption Test (ISAT). Seventy-two concrete cubes with different mixture proportions were prepared and tested. The objectives were to examine how ISAT values are influenced by conditioning, time, water-cement ratio, and concrete grade. ISAT was performed on saturated conditioned cubes to characterize near-surface absorption for different mixtures. Results showed ISAT values increased at initial time points for lower strength mixtures, and decreased over time. Charts were developed to provide a better assessment of normal strength concrete permeability using ISAT.
The document discusses the durability of concrete, which is defined as its ability to resist weathering, chemical attack, and other deterioration processes over its lifespan. It notes that the interaction between concrete and its environment occurs through the hardened cement paste, allowing materials from the environment to permeate into the concrete. To improve durability, the document states that environments must be better classified so that appropriate cements, water-cement ratios, reinforcement covers, and crack widths can be selected. Lower water-cement ratios produce denser, less permeable concrete and therefore improve durability by reducing cracks and disintegration over time.
Investigation on Flexural Strength of High Strength Silica Fume ConcreteIRJET Journal
This document investigates the flexural strength of high-strength concrete with different replacement levels of cement with silica fume. Standard prisms were tested to analyze the flexural strength at 7 and 28 days. The results showed that the flexural strength reached a maximum value at 12% cement replacement with silica fume for M40 grade concrete. Workability tests of the mixes found that slump and compaction factor decreased as the amount of silica fume increased, with the lowest values at 15% replacement level. In conclusion, adding silica fume as a partial cement replacement was found to improve the flexural strength properties of high-strength concrete.
EFFECT OF DEAD SEA WATER ON DURABILITY, STRENGTH, FLEXURE AND BOND ON HARDENE...IAEME Publication
The purpose of this research is to study on the effect of the Dead Sea water on
concrete structures. The normal concrete is usually mixed and cured with fresh water
in order to protect the concrete from alkali attack which may lead to expansion and
deterioration and finally loss of durability of concrete. Compressive strength,
absorption, corrosion of steel, bond stress, and flexural stress were investigated in fresh
and saline (Dead Sea) waters. Salt durability, compressive strength, flexural stress, and
bond stress significantly decreased after exposure of concrete to Dead Sea saline water
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
Temperature and shrinkage effect on structural analysis - 10.01.03.072Mohammed_Shakib
This document summarizes the effects of shrinkage and temperature changes on concrete, including:
- Shrinkage occurs as free water evaporates from concrete, causing cracks if not controlled. It can cause stresses in statically indeterminate structures and loss of pre-stress.
- The amount of shrinkage depends on water-cement ratio, cement content, aggregate type and content. It can be reduced by decreasing water, increasing aggregate, and proper curing.
- Temperature changes cause expansion and contraction that can also cause cracks. The coefficient of thermal expansion is typically 4-7x10-6 per °F.
- Both shrinkage and temperature effects are important to consider in concrete design to
Effect of water cement ratio on the compressive strength of gravel - crushed ...Alexander Decker
Reducing the water-cement ratio of concrete mixtures containing crushed over burnt bricks as a partial replacement for natural gravel as a coarse aggregate was found to increase the compressive strength of the concrete. A mixture with a 2:2 ratio of gravel to crushed bricks by volume and a water-cement ratio of 0.4 achieved the highest compressive strength of 35.9 MPa at 28 days. Using crushed over burnt bricks alone as the coarse aggregate still produced concrete but with lower strength, with a maximum strength of 29.5 MPa obtained at a water-cement ratio of 0.4. In general, decreasing the water-cement ratio was found to increase the compressive strength of the concrete mixtures by over
Permeability of concrete, chemical attack, acid attack, efflorescence, Corrosion in concrete. Thermal conductivity, thermal diffusivity, specific heat. Alkali Aggregate Reaction
High Performance Concrete & Durability of ConcreteAbhal Gudhka
This e-poster by students from A. D. Patel Institute of Technology discusses high performance concrete (HPC) and concrete durability. HPC has improved workability, high strength, and durability. The poster explains factors affecting concrete durability like permeability and chemical attacks. It presents methods to improve durability including using mineral and chemical admixtures. Specifically, fly ash is discussed as an admixture that improves strength, permeability, alkali-silica reaction resistance, and reduces heat of hydration. A case study on a university building that used high volume fly ash concrete is also summarized.
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.
Study of mechanical properties of concrete at elevated temperatures a revieweSAT Journals
Abstract Concrete, the second highest consumed material after water in the world, plays a vital role in the construction field because of the versatility in its use. Developments during the last two decades have shown a marked increase in the number of structures involving the long time heating of concrete. In recognition of its importance, many researchers have attempted to investigate the effect of elevated temperature on mechanical properties of concrete. These researchers, during their investigation, used materials with varying combination and different experimental conditions. These materials include cement, different percentages of admixtures like fly ash, silica fume, metakaolin, finely grounded pumice(FGP), group granulated blast furnace slag(GGBS), polypropylene fibre(PP fibre), palm oil fuel ash(POFA), Portland pozzolana cement(PPC), rice husk ash(RHA), different fine and coarse aggregates, super plasticisers, retarders and the conditions included a temperature range of 28oC to 1200oC . The other conditions that were varied are the shapes and sizes of test specimens, curing methods, curing conditions and test methods. The analysis of these investigations and their results are reviewed and presented in this paper. Key words: concrete, mechanical properties, elevated temperature, admixtures, curing methods
This document discusses a study on the effect of using Sudanese aggregates and supplementary cementitious materials like silica fume and fly ash to produce high strength concrete. Hundreds of concrete specimens with different mixtures of local materials, silica fume, fly ash, and water-cement ratios were tested to determine compressive strength and workability. The results showed that local Sudanese materials can be used to successfully produce concrete with a compressive strength of 80 MPa when combined with supplementary cementitious materials. Water-cement ratio had an inverse relationship with compressive strength. Silica fume improved short and long-term concrete properties while fly ash inversely affected 28-day strength. The study aims to provide insights for producing
The environmental impacts of calcium chloride addition to cement on reinforci...Alexander Decker
This document discusses the environmental impacts of adding calcium chloride to cement on reinforcing steel corrosion. It finds that chloride ions from calcium chloride can more quickly penetrate low-alumina cement mortar compared to moderate-alumina cement mortar. The addition of calcium chloride to cement was also found to decrease the electrical potential of steel reinforcement and increase the rate of corrosion, especially at higher water-cement ratios. While calcium chloride can accelerate cement setting in concrete, its use also increases the risks of steel corrosion through depassivation unless concentrations and exposure temperatures are carefully controlled.
AI for Legal Research with applications, toolsmahaffeycheryld
AI applications in legal research include rapid document analysis, case law review, and statute interpretation. AI-powered tools can sift through vast legal databases to find relevant precedents and citations, enhancing research accuracy and speed. They assist in legal writing by drafting and proofreading documents. Predictive analytics help foresee case outcomes based on historical data, aiding in strategic decision-making. AI also automates routine tasks like contract review and due diligence, freeing up lawyers to focus on complex legal issues. These applications make legal research more efficient, cost-effective, and accessible.
Concrete is a composite material made of coarse aggregate bonded together with a fluid cement that hardens over time. The document discusses properties of both fresh and hardened concrete, including workability, strength, permeability, durability, response to temperature changes, and causes of damage. It provides definitions of key terms, describes tests used to evaluate properties like slump and compressive strength, and explains factors that affect the durability of concrete such as permeability, sulfate attack, freezing and thawing, and corrosion of reinforcing steel.
Flexural Behavior of Fibrous Reinforced Cement Concrete Blended With Fly Ash ...Ijripublishers Ijri
This document discusses high strength concrete that is reinforced with fibers. It provides background on concrete composites and describes how high strength concrete is achieved through methods like using a lower water-cement ratio or supplementary cementitious materials. The document focuses on fiber reinforced concrete and the benefits fibers provide, such as improved strength and crack resistance. It also discusses different types of fibers like steel fibers and their properties. Blended cements and use of pozzolanic materials like metakaolin and fly ash are described as ways to further improve concrete strength and durability.
Development of high-strength, economical self-consolidating concretePubl 2022
Naık T. R. , Kumar R., Ramme B. W. , Canpolat F.
This paper presents information regarding development, properties, and advantages and disadvantages of using high-strength self-consolidating concrete in the construction industry. It also presents results of a study recently completed for manufacturing economical high-strength self-consolidating concrete containing high-volumes of fly ash. In this study, portland cement was replaced by Class C fly ash in the range of 35-55% by the mass of cement. The results of fresh and hardened properties of concrete show that the use of high-volumes of Class C fly ash in self-consolidating concrete reduces the requirements for superplasticizer (HRWRA) and viscosity modifying agent (VMA) compared with the normal dosage for such admixtures in self-Consolidating concrete. The results further indicate that economical self-consolidating concrete with 28-day strengths up to 62 MPa can be made using high-volumes of fly ash. Such concretes can be used for a wide range of applications from cast-in-place to precast concrete construction.
DOI:10.1016/j.conbuildmat.2011.12.025
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.
Study of Compressive and Flexural Strength of Fibrous Triple Blended High Str...researchinventy
-Change has been a constant parameter within the concrete industry in view of increasing construction activities and most importantly an increased thrust in high quality yet economic structures. This change has thus, brought along with it, different trends in concrete technology with respect to the way in which it is perceived and more technically, its composition, its handling, mixing etc. . As a result, we have today, different types of concretes such as triple blended concrete, self-compacted concrete, bacterial concrete etc. which have, in their own respective manner, succeeded in enhancing the serviceability of the structure with which they are built, in comparison to ordinary concrete. In this report, we focus and emphasize on Triple Blended Concrete, its meaning, materials involved, process of casting, testing, salient features et al.
This document discusses self-compacting concrete (SCC), which is a type of concrete that can flow and consolidate under its own weight without any external vibration. SCC has advantages over traditional vibrated concrete such as easier placement in complex forms, reduced noise pollution, and improved surface finish. The key properties of SCC include high flowability, passing ability, and segregation resistance. These properties are achieved through optimizing the mix design, including using a high range of superplasticizer, limiting coarse aggregate content, increasing fine particles and viscosity modifying agents. SCC has applications in structures with dense reinforcement like the Burj Khalifa where it simplified construction. The document also discusses experimental investigations into the compressive strength of SCC exposed to
Evaluation of Saturated Conditioned Concrete Cubes by Initial Surface Absorpt...IRJET Journal
This document presents research on evaluating saturated concrete cubes using an Initial Surface Absorption Test (ISAT). Seventy-two concrete cubes with different mixture proportions were prepared and tested. The objectives were to examine how ISAT values are influenced by conditioning, time, water-cement ratio, and concrete grade. ISAT was performed on saturated conditioned cubes to characterize near-surface absorption for different mixtures. Results showed ISAT values increased at initial time points for lower strength mixtures, and decreased over time. Charts were developed to provide a better assessment of normal strength concrete permeability using ISAT.
The document discusses the durability of concrete, which is defined as its ability to resist weathering, chemical attack, and other deterioration processes over its lifespan. It notes that the interaction between concrete and its environment occurs through the hardened cement paste, allowing materials from the environment to permeate into the concrete. To improve durability, the document states that environments must be better classified so that appropriate cements, water-cement ratios, reinforcement covers, and crack widths can be selected. Lower water-cement ratios produce denser, less permeable concrete and therefore improve durability by reducing cracks and disintegration over time.
Investigation on Flexural Strength of High Strength Silica Fume ConcreteIRJET Journal
This document investigates the flexural strength of high-strength concrete with different replacement levels of cement with silica fume. Standard prisms were tested to analyze the flexural strength at 7 and 28 days. The results showed that the flexural strength reached a maximum value at 12% cement replacement with silica fume for M40 grade concrete. Workability tests of the mixes found that slump and compaction factor decreased as the amount of silica fume increased, with the lowest values at 15% replacement level. In conclusion, adding silica fume as a partial cement replacement was found to improve the flexural strength properties of high-strength concrete.
EFFECT OF DEAD SEA WATER ON DURABILITY, STRENGTH, FLEXURE AND BOND ON HARDENE...IAEME Publication
The purpose of this research is to study on the effect of the Dead Sea water on
concrete structures. The normal concrete is usually mixed and cured with fresh water
in order to protect the concrete from alkali attack which may lead to expansion and
deterioration and finally loss of durability of concrete. Compressive strength,
absorption, corrosion of steel, bond stress, and flexural stress were investigated in fresh
and saline (Dead Sea) waters. Salt durability, compressive strength, flexural stress, and
bond stress significantly decreased after exposure of concrete to Dead Sea saline water
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
Temperature and shrinkage effect on structural analysis - 10.01.03.072Mohammed_Shakib
This document summarizes the effects of shrinkage and temperature changes on concrete, including:
- Shrinkage occurs as free water evaporates from concrete, causing cracks if not controlled. It can cause stresses in statically indeterminate structures and loss of pre-stress.
- The amount of shrinkage depends on water-cement ratio, cement content, aggregate type and content. It can be reduced by decreasing water, increasing aggregate, and proper curing.
- Temperature changes cause expansion and contraction that can also cause cracks. The coefficient of thermal expansion is typically 4-7x10-6 per °F.
- Both shrinkage and temperature effects are important to consider in concrete design to
Effect of water cement ratio on the compressive strength of gravel - crushed ...Alexander Decker
Reducing the water-cement ratio of concrete mixtures containing crushed over burnt bricks as a partial replacement for natural gravel as a coarse aggregate was found to increase the compressive strength of the concrete. A mixture with a 2:2 ratio of gravel to crushed bricks by volume and a water-cement ratio of 0.4 achieved the highest compressive strength of 35.9 MPa at 28 days. Using crushed over burnt bricks alone as the coarse aggregate still produced concrete but with lower strength, with a maximum strength of 29.5 MPa obtained at a water-cement ratio of 0.4. In general, decreasing the water-cement ratio was found to increase the compressive strength of the concrete mixtures by over
Permeability of concrete, chemical attack, acid attack, efflorescence, Corrosion in concrete. Thermal conductivity, thermal diffusivity, specific heat. Alkali Aggregate Reaction
High Performance Concrete & Durability of ConcreteAbhal Gudhka
This e-poster by students from A. D. Patel Institute of Technology discusses high performance concrete (HPC) and concrete durability. HPC has improved workability, high strength, and durability. The poster explains factors affecting concrete durability like permeability and chemical attacks. It presents methods to improve durability including using mineral and chemical admixtures. Specifically, fly ash is discussed as an admixture that improves strength, permeability, alkali-silica reaction resistance, and reduces heat of hydration. A case study on a university building that used high volume fly ash concrete is also summarized.
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.
Study of mechanical properties of concrete at elevated temperatures a revieweSAT Journals
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Effect of curing: conditions on strength and durability of high-performance concrete
1. Scientia Iranica A (2017) 24(2), 576{583
Sharif University of Technology
Scientia Iranica
Transactions A: Civil Engineering
www.scientiairanica.com
Research Note
Eect of curing conditions on strength and durability of
high-performance concrete
F. Canpolata,b; and T.R. Naikb
a. Yildiz Technical University, Faculty of Civil Engineering, Department of Civil Engineering, Davutpasa Campus, Istanbul, Turkey
34220.
b. UWM Center for By-Products Utilization, Department of Civil Engineering and Mechanics, University of Wisconsin-Milwaukee,
P.O. Box 784, Milwaukee, WI 53201, USA.
Received 14 November 2014; received in revised form 6 October 2015; accepted 23 February 2016
KEYWORDS
Compressive strength;
Curing;
Fly ash;
High-performance
concrete;
Sulfate resistance;
Temperature.
Abstract. This paper describes the eects of variable curing temperatures on compressive
strength and sulfate resistance of high-strength, high-performance concrete. Two dierent
concrete mixtures were proportioned to attain the 56-day compressive strength of about
70 MPa upon moist-curing. One mixture contained more quantity of ASTM Class C
y
ash than the other one. For each mixture, one set of specimens was cured in a standard
moist-curing room at 23C and 100% relative humidity; another set of specimens was
sealed in plastic bags and cured in an elevated, Variable-Temperature Curing Environment
(VTCE). The average temperature of the VTCE oscillated between about 30C and 41C
once per day. This study revealed that the VTCE-cured concrete did not signi
2. cantly
exhibit dierent compressive strength or ability to resist sulfates attack compared to the
standard moist-cured specimens. Thus, it was concluded, based on the results of this
research, that additional eort to stabilize higher curing-temperatures would be necessary
for
4. F. Canpolat and T.R. Naik/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 576{583 577
reaction, while lower curing temperatures will retard
the hydration reaction. In fact, when the temperature
was increased by about 7C, the hydration reaction
rate was reported to increase by 100% [2]. Elevated
curing temperatures aect hardened concrete in two
ways. First, at the microscopic level, Calcium-Silicate-
Hydrate (C-S-H) crystals grow quickly, although they
are thin, long, and wide. These long, wide crystals are
comparatively large, but do not occupy all the available
pore space within the concrete matrix. Second, the
elevated curing temperatures usually prompt a greater
water loss due to evaporation, leaving unhydrated
cementitious particles in the concrete matrix, as well
as the voids which are created by the evaporated water
and are not yet
5. lled with C-S-H crystals. Therefore,
the concrete cured at higher temperatures tends to
exhibit a more porous microstructure. This leads to
lower long-term concrete strength and decreases the
ability of the concrete to resist penetration of harmful
substances such as sulfate-bearing water, for example
in the marine environment. So, even if desired strength
levels are achieved, porosity alone may prove to be
a source of a serious challenge to durability issue in
concrete structures constructed under a hot-weather
curing condition.
High-Performance Concrete (HPC) has become
an attractive option compared to normal-strength con-
crete. HPC is a specialized concrete designed to
provide several bene
6. ts in the construction of concrete
structures. HPC oers high strength, better durability
properties, and good construction. High strength is
one of the important attributes of HPC [3].
The advancement of High-Strength Concrete
(HSC) has aected nearly every area of concrete
construction. Since high-strength concrete (higher
than 40 MPa at the 28-day age [4]) is now generally
readily obtainable, the application of HSC as a viable
construction material is now well accepted. However,
if HSC is to be the construction material for use
in any condition, then other properties must also be
achieved in addition to the strength [5]. Some of
these properties include, but are not limited to, the
following: resistance to expansion caused by sulfate and
alkali-silica reaction, low permeability to air and water,
resistance to cycles of freezing and thawing, as well as
chloride-ion penetration.
HSC, with high durability, is sometimes re-
ferred to as High-Performance Concrete (HPC). Un-
like normal-strength concretes, high-strength concretes
must almost always employ supplementary cementi-
tious materials, chemical admixtures, and improved
mixture proportioning, and handling/placement tech-
niques. HSC is believed to be a more sensitive
material than traditional normal-strength concrete [6].
Therefore, additional care must be exercised for such
concretes in mixture proportioning and construction,
often leading to increased costs. Despite these costs,
HSC has proved to be a very economical option for
certain structural elements such as columns for high-
rise buildings [7-9].
The
7. rst uses of HPC in the 1970s were indoor
applications, mainly in columns in high-rise buildings,
which are not subjected to a particularly severe envi-
ronment. Outdoor applications of HPC date back to
the late 1980s and early 1990s, which means that not
enough time has passed to fully assess the real service
life of HPC structures under outdoor conditions. But,
based on the experience with ordinary concrete, one
can assume that HPC is more durable than ordinary
concrete. Indeed, the experience gained with ordinary
concrete has shown that concrete durability is governed
by concrete permeability and the harshness of the
environment [5,10].
Permeability dictates the rate at which aggres-
sive agents penetrate into the concrete, leading to
various types of undesirable physical and/or chemical
reactions. The aggressive agents include gases (CO2,
SOx, and NOx) and liquids (acid rain, salt-bearing
water, sea water, sulfate-bearing water, snow and ice
water, and river or lake
owing water). The primary
variables in
uencing concrete permeability are water
to cementitious materials ratio, quantities of supple-
mentary cementitious materials, grading and size of
aggregates, compaction of concrete, and curing [5,11].
Seawater is not a particularly harsh environment
for plain concrete, but such a marine environment
can be very harmful to reinforced concrete due to the
multiplicity of aggression that it can face. Marine
concrete structure is widely concerned about long-term
serviceability. It is well known that the destruction
of concrete structure in marine environment is mainly
due to sulfate attack and the corrosion of steel under
chloride attack [12]. In a marine environment, a
concrete structure is mainly subjected to four types
of aggressive factors [13]. They are as follows:
1. Chemical factors related to the presence of various
ions dissolved in the seawater or transported in the
wet air;
2. Geometrical factors related to the
uctuation of the
sea level, waves, tides, storms, and other similar
factors;
3. Physical forces such as freezing and thawing, scal-
ing, wetting and drying, abrasion, and other similar
factors;
4. Mechanical factors such as the kinetic action of the
waves and the erosion caused by sand [11].
Most sea waters are more or less the same
in composition, containing about 3.5% soluble salts
(chlorides and sulfates) by mass. The pH of seawa-
ter varies from 7.5 to 8.4, averaging about 8.2 [11].
8. 578 F. Canpolat and T.R. Naik/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 576{583
Concrete exposed to seawater may deteriorate from
the combined eects of the following chemical and
physical processes [14]: sulfate attack; leaching of lime
(primarily and easily dissolvable calcium hydroxide)
from the concrete; alkali-aggregate expansion; scaling
and/or salt crystallization from alternate wetting and
drying; freezing and thawing; corrosion of embedded
reinforcing or pre-stressing steel; and erosion and
abrasion from waves. Attack by most of these processes
can be slowed by reducing the permeability of concrete.
Low permeability helps keep aggressive chemicals out
of the concrete, slows leaching of soluble materials
such as lime, and limits the depth of carbonation,
thereby protecting the reinforcing steel better from
corrosion [14].
Marine concrete can be classi
9. ed according to
their exposure zones: submerged, splash, and atmo-
spheric. The submerged zone is continuously covered
by seawater, the splash zone is subject to continuous
wetting and drying, and the atmospheric zone is above
the splash zone and subject to occasional seawater
spray [14]. Concrete in the submerged zone is not
as vulnerable as concrete in the other two zones.
Deterioration in any of these zones tends to make the
concrete more porous and weak, making the concrete
susceptible to more deterioration. Cracks, spalls,
mortar erosion, and corrosion stains are the early
visible signs of deterioration [14].
Seawater can be very harmful to reinforced con-
crete, because once the chloride ions reach reinforcing
steel and steel corrosion occurs, it can result in a
rapid spalling of the cover concrete. Consequently, it
becomes easier for the chloride ions to reach the second
level of reinforcing steel, etc. By specifying a very
dense, impervious concrete and placing it correctly,
and by increasing the thickness of the concrete cover,
the corrosion of the steel can be either inhibited or
delayed [13].
The compressive strength of high-strength high-
performance concrete depends upon an ecient and
judicious use of Other Cementitious Materials (OCM).
These materials augment the chemical reactions pro-
duced by the portland cement and water. The result
from OCM reactions is a tight, densely packed concrete
matrix, which produces a strong bond between the
aggregates and the cementitious binder. The most
eective OCM, capable of producing signi
10. cantly im-
proved microstructure and compressive strength of the
concrete, is silica fume. Experiments have shown
that silica fume used as a replacement for portland
cement at a level of about 10% seems to give opti-
mum strength [15,16]. Unfortunately, silica fume is
expensive and presents diculties in traditional mixing
and
12. ts of silica fume are fairly well known,
they are often misunderstood. With regard to the
usual porosity-strength relationship for plain concrete,
a reduction in porosity cannot be directly correlated
with the silica fume use. This is because porosity is a
stronger function of the water-cementitious materials
ratio [19]. Other sources [17,20] speci
14. cant trouble area in high-
strength concrete production. Therefore, the amount
of water added to a concrete mixture is critical and
must be carefully determined if one is to make use of
the important bene
15. ts of the silica fume.
One of the more common methods of attaining
improved strength concrete economically is to add
y
ash to concrete mixtures. Fly ash is favorable for
use in high-strength concrete, with or without silica
fume, for reasons other than economics. As
y ash is
added to the concrete mixture, slump increases [21,22].
Therefore,
y ash in silica-fume concrete also enhances
workability while contributing to improved compressive
strength development. High-calcium
y ash (ASTM
C 618 designation Class C) is cementitious as well
as pozzolanic. Therefore, it is able to supplement
the performance of portland cement and combine
it with calcium hydroxide, an important ingredient
contributing to the hydration reaction. Studies have
indicated that compressive strength values increase in
mixtures containing Class C
y ash [5,23-26]. At
cement replacement levels exceeding 45%, Class C
y
ash may be responsible for reductions in very early-
age compressive strength value. While
y ash increases
workability of high-strength concrete with or without
silica fume, the use of a High-Range Water-Reducing
Admixture (HRWRA) is still indispensable for such
concretes with silica fume. Fly ash was used to improve
strength and durability of such concrete mixtures.
Sulfate attack on concrete can manifest itself
through two distinct forms [10]. First, sulfate ingress
may prompt concrete to undergo deleterious expan-
sions, causing cracking or spalling. Second, sulfates can
cause a progressive loss of mass and loss of strength of
concrete. Whichever of these two deterioration pro-
cesses is prevalent under a given set of circumstances
depends upon the concentration and source of the
sulfate ions. Calcium hydroxide and alumina-bearing
phases of hydrated portland cement are particularly
vulnerable to attack by sulfate ions. If the tricalcium
aluminate content of the portland cement is greater
than 8%, the hydration reaction may cause the de-
velopment of an expansive form of sulfate [11]. This
substance is known as ettringite fC3A + 3 CaSO4 !
ettringiteg. Ettringite is a crystalline structure capable
of swelling with the absorption of water.
It is well known and accepted that inclusion of
Class F
y ash in concrete would increase the resistance
of concrete to sulfate attack [27]. Based on extensive
microscopic investigation of blended cement pastes
16. F. Canpolat and T.R. Naik/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 576{583 579
containing several
y ashes, Mehta [28] reported that
irrespective of the calcium content, it is the amount
of reactive alumina contributed by a
y ash (from the
dissolution of the aluminosilicate glass and hydration
of crystalline compounds, such as C3A and C4A3S),
which controls the presence of the minerals highly
vulnerable to sulfate attack. Mehta [29] also found
that some high-calcium
y ashes formed ettringite as
a product of hydration. As a result, such
y ash
may experience the expansion and strength loss due
to sulfate exposure. Similar results, with regard to
sulfate resistance of Class C
y ash in concrete, were
obtained by Manz and McCarthy [30]. The increase
of
y ash replacement in concrete clearly reduces the
chloride penetration, chloride penetration coecient,
and steel corrosion in concrete [12].
2. Experimental program
The scope of this study involves two types of HPC
mixtures: production-grade (P) and experimental-
grade (E) HPC mixtures. A concrete mixture with
proven capability to achieve strengths in excess of 70
MPa (10000 psi) was used as the control mixture, the
production-grade mixture (Mixture 10P). In addition,
a more cost-eective, experimental-grade concrete mix-
ture (Mixture 10E) was also produced and tested.
2.1. Materials
ASTM C 150 Type I portland cement was used in this
investigation. The
17. ne aggregate used was natural
sand. A crushed limestone with nominal maximum
size of 19 mm was used as the coarse aggregate.
ASTM C 618 Class C
y ash and ASTM C 1240 silica
fume were used as mineral admixtures. ASTM C 494
High-Range Water-Reducing Admixture (HRWRA)
was used. ASTM C 494 retarding admixture was
used to permit placement and
18. nishing of the concrete
mixtures.
2.2. Mixture proportions
The proportions and fresh properties of the HPC
mixtures used for this study are presented in Table 1.
The concrete mixtures were proportioned to have the
56-day compressive strength of 69 MPa. Mixture
10P contained approximately 15%
y ash by mass of
cementitious materials (cement +
y ash), and Mixture
10E contained 40%
y ash. Slump values of the
concrete mixtures exceeded 200 mm.
2.3. Preparation of test specimens
From each concrete mixture, 100 mm 200 mm cylin-
drical specimens were cast for compressive strength
measurement. The specimens for sulfate-resistance
test were 100 mm 75 mm 400 mm prisms. All
specimens were cast in accordance with ASTM C
192 [31].
Table 1. Mixture proportions and fresh properties of
concrete.
Mixture number 10P 10E
Cement (kg/m3) 387 298
Fly ash, class C (kg/m3) 71 201
Water (kg/m3) 142 154
Sand, SSD (kg/m3) 737 715
Crushed stone, 19 mm
max., SSD (kg/m3)
1010 1029
HRWRA (L/m3) 2.79 2.83
Retarding admixture (L/m3) 0.89 0.93
w=c 0.37 0.52
w=cm 0.31 0.31
Slump (mm) 216 241
Air content (%) 5.0 2.4
Density (kg/m3) 2350 2400
2.4. Curing of specimens
After casting, all the molded specimens were covered
with plastic sheets to minimize moisture loss due to
evaporation. After 24 8 hours, the specimens were
demolded and transferred to a standard moist-curing
room or a specially-designed curing unit.
Two types of curing environments were used to
provide the necessary insight into the development
of hardened HPC properties as a function of curing
temperature. The
19. rst environment was the standard
moist-curing in a moist room maintained at 23
1C temperature and 100% relative humidity. The
second curing environment was an elevated Variable-
Temperature Curing Environment (VTCE) to simulate
hot-weather curing conditions. The average temper-
ature of the VTCE was raised from about 30C to
41C in 8 hours and lowered from 41C to 30C in
16 hours, completing one cycle each day (Figure 1).
The concrete specimens were wrapped and sealed in a
plastic bag before placing them in the VTCE chamber
in order to minimize moisture loss due to evaporation.
The relative humidity of the VTCE chamber was found
to vary between 35 and 85%.
Figure 1. Recorded temperature for VTCE.
20. 580 F. Canpolat and T.R. Naik/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 576{583
2.5. Testing of specimens
For each concrete mixture and curing environment,
the compressive strength was determined for three
cylinders (total 21 cylinders) at 3, 7, 28, 56, 91,
182, and 365 days of age in accordance with ASTM
C 39. Upon obtaining the desired compressive-strength
level of 69 MPa, prism specimens were immersed in
a 10% sodium sulfate solution. The sulfate-resistance
test specimens were tested for the change in dynamic
modulus of elasticity to determine the soundness of
concrete (ASTM C88). The sulfate-resistance test
continued for a period of 420 days.
3. Test results and discussion
3.1. Compressive Strength
Compression test results of Mixtures 10P and 10E
are presented in Figure 2 and Table 2. Mixture 10P
exceeded the target 56-day compressive strength of
70 MPa. Both the normal moist-curing environment
and VTCE did not produce signi
21. cant dierences in
strength gains for Mixture 10P over the early curing
period of 91 days. Beyond the 91-day age, the moist-
cured 10P specimens showed almost constant strength
with age, and the VTCE-cured 10P specimens showed
a reduction in strength with age possibly due to
desiccation of concrete. Accordingly, the coecient of
variation for 10P mixes was 3%, and the maximum co-
Figure 2. Compressive strength of concrete mixtures.
Table 2. Compressive strength of concrete mixtures
(MPa).
Age
(days)
10P
moist
cured
10P
VTCE
cured
10E
moist
cured
10E
VTCE
cured
3 52.5 47.8 32.6 34.1
7 53.7 58.0 43.7 50.9
28 73.3 72.7 67.4 63.0
56 72.8 77.6 65.8 58.4
91 82.1 83.1 77.2 67.6
182 78.6 70.7 77.6 63.7
365 78.3 68.7 83.3 55.2
ecient of variations for 10E mixes was 5%. According
to ACI 214 (Standards of Concrete Control) [32], a 5%
maximum coecient of variation is considered fair
for laboratory trial batches. Values in excess of 5% are
considered poor.
Mixture 10E reached the 56-day strength of
66 MPa after moist curing and 58 MPa after curing
in the VTCE. Moist-cured 10E specimens continued
to gain strength with age, while the VTCE-cured 10E
specimens showed a reduction in strength beyond the
91-day age.
If the relative humidity of the air surrounding the
specimens in the VTCE had been 100%, the long-term
strength of VTCE-cured 10P and 10E specimens might
have been higher. Based on the strength results of the
moist-cured specimens and the VTCE-cured specimens
at the early age of up to about three months, it may
be said that the elevated, variable curing temperature
did not aect the compressive strength of concrete
noticeably.
3.2. Sulfate resistance
Fundamental longitudinal frequencies of each concrete
specimen were recorded at predetermined intervals per
ASTM C215 [33]. These data were used to compute
any change in dynamic modulus of the concrete occur-
ring over the test period. Fundamental longitudinal
frequencies of each concrete in Figure 3 and Table 3
present test results pertaining to the change in dynamic
modulus versus the time of sulfate exposure. An
increase in dynamic modulus implies an improvement
in microstructure of the concrete. After storage in
the sodium sulfate solution, both the moist-cured
specimens and the VTCE-cured specimens showed
considerable increase in the dynamic modulus. Study
of Shah et al. [34] showed that nanoindentation along
with imaging is a powerful technique to determine
the mechanical properties of dierent phases of micro-
and nano-structure of cement paste. Young's modulus
of unhydrated cement particles and C-S-H gel was
determined by Shah et al. Using the imaging capability
of the nanoindenter tip made it possible to position
Figure 3. Change in dynamic modulus of concrete due to
exposure to sulfate solution.
22. F. Canpolat and T.R. Naik/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 576{583 581
Table 3. Change in dynamic modulus of concrete due to
exposure to sulfate solution.
Age
(days)
10P
moist
cured
(%)
10P
VTCE
cured
(%)
10E
moist
cured
(%)
10E
VTCE
cured
(%)
7 101.68 102.52 103.63 106.73
14 102.94 103.44 105.59 107.7
21 103.54 104.13 106.41 108.71
28 103.97 105.08 107.26 109.07
56 105.25 106.77 109.17 110.69
91 106.56 107.74 110.8 112.22
105 107.17 108.19 111.18 113.04
140 107.57 108.58 111.64 113.29
182 107.92 108.93 111.92 113.97
273 108.56 109.06 112.2 114.12
420 108.63 109.94 112.06 114.55
the indenter exactly in the narrow region of Interfacial
Transition Zone (ITZ) and perform nanoindentation to
determine the local mechanical properties directly. It
was found that the paste in the ITZ has, in general, a
lower Young's modulus [34].
Moist-cured specimens of both 10P and 10E mix-
tures recorded somewhat lower values of the increase in
the dynamic modulus than their VTCE-cured counter-
parts. The behavior of these specimens indicates that
exposure to severe sulfate solutions would not result
in the internal deterioration of this class of concrete, at
least over the 420-day test period. It is, therefore, likely
that the 70 MPa concrete tested was not susceptible to
the formation of expansive ettringite as a result of the
exposure to the sulfate solution.
4. Conclusions
Substantial dierences in strength-gain behavior and
long-term strengths between moist-cured specimens
and VTCE-cured specimens were expected in the
evaluation of curing temperature eects. The absence
of these dierences in this research indicates that
eorts to stabilize curing temperatures may not be
necessary to attain approximate moist-cured specimen
strengths for concrete cured under summer-weather
variable temperatures.
Specimen measurements involving changes in dy-
namic modulus were analyzed to illustrate the eects of
sulfate attack and for dierences in behavior between
moist-cured specimens and VTCE-cured specimens.
The eect of curing was insigni
23. cant on the sulfate
resistance of the HPC mixtures tested in this inves-
tigation. The absence of any considerable dierential
behavior between identical concretes cured in dierent
environments substantiates the conclusion that eorts
to maintain normal curing temperatures are probably
necessary to attain moist-cured levels of sulfate resis-
tance for concrete cured under variable temperatures
as long as moisture loss is minimized.
Acknowledgments
The UWM Center for By-Products Utilization was es-
tablished in 1988 with a generous grant from Dairyland
Power Cooperative, La Crosse, Wisc.; Madison Gas
and Electric Company, Madison, Wisc.; National Min-
erals Corporation, St. Paul, Minn.; Northern States
Power Company, Eau Claire, Wisc.; We Energies,
Milwaukee, Wisc.; Wisconsin Power and Light Com-
pany, Madison, Wisc.; and, Wisconsin Public Service
Corporation, Green Bay, Wisc. Their
24. nancial support
and additional grant and support from Manitowoc
Public Utilities, Manitowoc, Wisc. are gratefully
acknowledged.
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Biographies
Fethullah Canpolat is an Assistant Professor in
Yildiz Technical University, Istanbul, Turkey. He spe-
cializes in Materials of Sustainable Construction and
Concrete Technology. He is a Former Post-Doctoral
Research Associate at UWM Center for By-Products
Utilization, in the University of Wisconsin-Milwaukee,
27. F. Canpolat and T.R. Naik/Scientia Iranica, Transactions A: Civil Engineering 24 (2017) 576{583 583
where he was involved with research on the use of
recyclable materials such as coal combustion products,
cement kiln dust, limestone quarry
28. nes, and foundry
industry silica-dust in cement-based materials, such as
concrete.
Tarun R Naik, FACI, is an Emeritus Professor of
Structural Engineering at the University of Wisconsin-
Milwaukee and Former Research Professor and Aca-
demic Program Director of the UWM Center for By-
Products Utilization. He was a member of ACI's
Board Advisory Committee on Sustainable Develop-
ment; and ACI Committees 123, Research and Current
Developments; 214, Evaluation of Results of Tests
Used to Determine the Strength of Concrete; 229,
Controlled Low-Strength Materials; 232, Fly Ash and
Natural Pozzolans in Concrete; and 555, Concrete with
Recycled Materials.