Assessment of the fire-induced spalling of high strength concrete in concrete structures requires knowledge of the tensile strength of concrete at an elevated temperature. However, previous research is mainly focused on determining residual tensile strength, measured at the post-fire stage after cooling the specimens to ambient temperature. However, such residual tensile strength is only applicable to concrete after fire exposure and not during the fire event, which is usually more critical. In this study, the early residual splitting tensile strength of concrete at high temperature is determined experimentally. The test results indicate that early residual splitting tensile strength decreases with temperature. To understand this phenomenon, temperature distribution is examined. Compared to residual tensile strength, loss of early residual splitting tensile strength is found to be faster due to the elevated temperature effect. Lastly, in order to reproduce early residual splitting tensile strength, a numerical model is developed and empirical expressions are proposed for engineering application.
{"title":"Early residual splitting tensile strength of concrete at elevated temperature","authors":"Zhiwei Shan, Zhuo-wei Wu, S. Lo, R. Su","doi":"10.1680/jmacr.22.00209","DOIUrl":"https://doi.org/10.1680/jmacr.22.00209","url":null,"abstract":"Assessment of the fire-induced spalling of high strength concrete in concrete structures requires knowledge of the tensile strength of concrete at an elevated temperature. However, previous research is mainly focused on determining residual tensile strength, measured at the post-fire stage after cooling the specimens to ambient temperature. However, such residual tensile strength is only applicable to concrete after fire exposure and not during the fire event, which is usually more critical. In this study, the early residual splitting tensile strength of concrete at high temperature is determined experimentally. The test results indicate that early residual splitting tensile strength decreases with temperature. To understand this phenomenon, temperature distribution is examined. Compared to residual tensile strength, loss of early residual splitting tensile strength is found to be faster due to the elevated temperature effect. Lastly, in order to reproduce early residual splitting tensile strength, a numerical model is developed and empirical expressions are proposed for engineering application.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44102722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kanchan K. Kole, S. Gautham, P. Khan, Ripan K. Biswas, Kajari Dasgupta, A. K. Mandal, M. B. Anoop, J. Ghosh, S. Sasmal
Cement hydration has a direct influence on the mechanical and durability properties of concrete. Understanding the formation and evolution of hydration products at atomic scale during different stages of hydration is important in order to engineer the material for specific performance. However, research investigations on effects of addition of supplementary materials like fly ash (FA) on the development of atomic scale structure of the major hydration product (namely, Calcium-Silicate-Hydrate C-S-H) and its correlations with nano-mechanical properties (through complementary physico-chemical and nano-mechanical techniques) are scanty. In this work, fly ash was added to Portland Cement (PC) in different percentages (20% and 40%) to study its effect on the structural and mechanical properties at different phases of hydration (3 to 90 days). The evolution of C-S-H at atomic scale in cement-FA systems has been studied using XRD, APDF, HRTEM, FESEM and FTIR, and mechanical properties at different ages have been evaluated using nanoindentation technique. The information and critical observations from the present study provide significant information on intrinsic properties of hydrating cement composites which will help in developing low-energy cement composites for sustainable structures.
{"title":"Effect of fly ash on the atomic scale structure of C–S–H during Portland Cement hydration","authors":"Kanchan K. Kole, S. Gautham, P. Khan, Ripan K. Biswas, Kajari Dasgupta, A. K. Mandal, M. B. Anoop, J. Ghosh, S. Sasmal","doi":"10.1680/jmacr.22.00327","DOIUrl":"https://doi.org/10.1680/jmacr.22.00327","url":null,"abstract":"Cement hydration has a direct influence on the mechanical and durability properties of concrete. Understanding the formation and evolution of hydration products at atomic scale during different stages of hydration is important in order to engineer the material for specific performance. However, research investigations on effects of addition of supplementary materials like fly ash (FA) on the development of atomic scale structure of the major hydration product (namely, Calcium-Silicate-Hydrate C-S-H) and its correlations with nano-mechanical properties (through complementary physico-chemical and nano-mechanical techniques) are scanty. In this work, fly ash was added to Portland Cement (PC) in different percentages (20% and 40%) to study its effect on the structural and mechanical properties at different phases of hydration (3 to 90 days). The evolution of C-S-H at atomic scale in cement-FA systems has been studied using XRD, APDF, HRTEM, FESEM and FTIR, and mechanical properties at different ages have been evaluated using nanoindentation technique. The information and critical observations from the present study provide significant information on intrinsic properties of hydrating cement composites which will help in developing low-energy cement composites for sustainable structures.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48132423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the influence of pore structures on the chloride diffusivity of cement pastes. A quantitative relationship between pore structure parameters (i.e., pore diameter, porosity, constrictivity, and tortuosity) and the diffusivity of cement paste is established. Microstructures of different pore structure parameters were generated, and then their diffusivities were predicted by 3D lattice diffusivity model. It was found that the pore diameter has little effect on the chloride diffusivity of the cement pastes, and the chloride diffusivity is significantly affected by porosity, constrictivity and tortuosity. The diffusivity is proportional to the porosity, proportional to the 2nd order polynomial of the constrictivity, and inversely proportional to the square of the tortuosity. The proposed model can provide a fundamental understanding for improving the diffusivity of cement-based composite materials.
{"title":"Study on the quantitative relationship between diffusivity and pore structure parameters of cement pastes","authors":"Liangyuan Xie, Lin Liu, Guanghui Tao","doi":"10.1680/jmacr.22.00262","DOIUrl":"https://doi.org/10.1680/jmacr.22.00262","url":null,"abstract":"This paper investigates the influence of pore structures on the chloride diffusivity of cement pastes. A quantitative relationship between pore structure parameters (i.e., pore diameter, porosity, constrictivity, and tortuosity) and the diffusivity of cement paste is established. Microstructures of different pore structure parameters were generated, and then their diffusivities were predicted by 3D lattice diffusivity model. It was found that the pore diameter has little effect on the chloride diffusivity of the cement pastes, and the chloride diffusivity is significantly affected by porosity, constrictivity and tortuosity. The diffusivity is proportional to the porosity, proportional to the 2nd order polynomial of the constrictivity, and inversely proportional to the square of the tortuosity. The proposed model can provide a fundamental understanding for improving the diffusivity of cement-based composite materials.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46256723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of exposing concrete beams (150 × 250 ×1600 mm), retrofitted with parabolic and straight profiles of NSM carbon FRP ropes, to mild and moderate stages of cyclic sulfate treatment (CST), is investigated as a part of an ongoing comprehensive study. A total of sixteen beams were used to evaluate structural performance for strengthened beams before and after exposure to CST for about 4 and 11 months when free concrete expansions of about 2008 and 8690 μ strain were attained, respectively. Mechanical tests on concrete cylinders showed increased brittleness of concrete due to the CST with 6% and 15% reductions in compressive strength after exposure to the mild and moderate stages of CST, respectively. The load capacity and stiffness for beams exposed to the mild stage of CST were slightly decreased, yet experienced noticeable increases for those exposed to the moderate stage of CST, owing to the significant pre-compressive stresses induced in concrete. In contrast, rotational ductility and toughness were progressively decreased as the treatment progressed. Generally, concrete beams, strengthened with curved and straight NSM CFRP ropes, cannot retain their overall structural performance under moderate levels of sulfate attack.
{"title":"Impact of sulfate attack extent on the flexural behavior of CFRP-strengthened concrete beams","authors":"R. Haddad, Hebah M. Al-Jabali","doi":"10.1680/jmacr.23.00019","DOIUrl":"https://doi.org/10.1680/jmacr.23.00019","url":null,"abstract":"The effect of exposing concrete beams (150 × 250 ×1600 mm), retrofitted with parabolic and straight profiles of NSM carbon FRP ropes, to mild and moderate stages of cyclic sulfate treatment (CST), is investigated as a part of an ongoing comprehensive study. A total of sixteen beams were used to evaluate structural performance for strengthened beams before and after exposure to CST for about 4 and 11 months when free concrete expansions of about 2008 and 8690 μ strain were attained, respectively. Mechanical tests on concrete cylinders showed increased brittleness of concrete due to the CST with 6% and 15% reductions in compressive strength after exposure to the mild and moderate stages of CST, respectively. The load capacity and stiffness for beams exposed to the mild stage of CST were slightly decreased, yet experienced noticeable increases for those exposed to the moderate stage of CST, owing to the significant pre-compressive stresses induced in concrete. In contrast, rotational ductility and toughness were progressively decreased as the treatment progressed. Generally, concrete beams, strengthened with curved and straight NSM CFRP ropes, cannot retain their overall structural performance under moderate levels of sulfate attack.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48531071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhongzhe Zhang, Yong-sheng Ji, Zhanguo Ma, Yanpeng Zhao, Zhishan Xu, Furong Gao, Qi Xue, M. Ma
The issue of low compressive strength in concrete is primarily caused by the anti-washout admixture (AWA) added to cement-based cementitious materials (CBCMs). In this paper, the AWA was added to alkali-activated cementitious materials (AACM) to prepare underwater non-dispersible concrete (UNDC). The effect of different AWA contents on the compressive strength of AACM was studied by measuring the compressive strength, hydration process, pore structure, microscopic appearance, and chemical composition. The results show that the compressive strength of AACM-UNDC moulded underwater can reach higher than 80% of the compressive strength of AACM-UNDC moulded on land. The polymerization and decomposition reaction of AACM can lead to the formation of strong covalent bonds, which can not only interweave with the long chain structure of AWA to form a dense network structure, but also can avoid the AWA wrapping on the surface of the activated material through the charge effect, and hinder the hydration reaction process of AASM.
{"title":"Effect of anti-washout admixture on the compressive strength of alkali-activated underwater non-dispersible concrete","authors":"Zhongzhe Zhang, Yong-sheng Ji, Zhanguo Ma, Yanpeng Zhao, Zhishan Xu, Furong Gao, Qi Xue, M. Ma","doi":"10.1680/jmacr.22.00239","DOIUrl":"https://doi.org/10.1680/jmacr.22.00239","url":null,"abstract":"The issue of low compressive strength in concrete is primarily caused by the anti-washout admixture (AWA) added to cement-based cementitious materials (CBCMs). In this paper, the AWA was added to alkali-activated cementitious materials (AACM) to prepare underwater non-dispersible concrete (UNDC). The effect of different AWA contents on the compressive strength of AACM was studied by measuring the compressive strength, hydration process, pore structure, microscopic appearance, and chemical composition. The results show that the compressive strength of AACM-UNDC moulded underwater can reach higher than 80% of the compressive strength of AACM-UNDC moulded on land. The polymerization and decomposition reaction of AACM can lead to the formation of strong covalent bonds, which can not only interweave with the long chain structure of AWA to form a dense network structure, but also can avoid the AWA wrapping on the surface of the activated material through the charge effect, and hinder the hydration reaction process of AASM.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48533121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Siyao Li, C. Fu, Weizhuo Shi, Qi He, Jiandong Wang
The use of slag-reinforced concrete is necessary due to environmental concerns around the world, but the decrease in concrete durability caused by chloride-ion rich environments requires more advanced concrete-mix designs, especially in coastal areas. This study aims to assess the influence of slag addition on chloride-ion transport performance in reinforced concrete beams under sustained bending moment, considering two conditions of environmental chlorine exposure: drying-wetting cycles and soaking. Results show that the chloride diffusion coefficient increases in tension zones and decreases in compression zones when the sustained bending load in concrete beams increases. However, the addition of slag can significantly reduce the chloride diffusion depth and diffusion coefficient values for both environmental conditions, with a more significant effect on the drying-wetting cycle. The chloride concentration on the surface of slag concrete (SC) in compression zones is greater than that in SC tension zones and that in ordinary concrete (OC) in both tension and compression zones. The study established a prediction model describing the chloride-penetration characteristics of concrete beams subjected to sustained bending moment. The proposed model is a reasonable approach for predicting chloride distribution in reinforced concrete beams with slag addition subjected to bending moments.
{"title":"Chloride penetration in reinforced slag-based concrete beams under combined effects of loads and drying-wetting cycles","authors":"Siyao Li, C. Fu, Weizhuo Shi, Qi He, Jiandong Wang","doi":"10.1680/jmacr.22.00331","DOIUrl":"https://doi.org/10.1680/jmacr.22.00331","url":null,"abstract":"The use of slag-reinforced concrete is necessary due to environmental concerns around the world, but the decrease in concrete durability caused by chloride-ion rich environments requires more advanced concrete-mix designs, especially in coastal areas. This study aims to assess the influence of slag addition on chloride-ion transport performance in reinforced concrete beams under sustained bending moment, considering two conditions of environmental chlorine exposure: drying-wetting cycles and soaking. Results show that the chloride diffusion coefficient increases in tension zones and decreases in compression zones when the sustained bending load in concrete beams increases. However, the addition of slag can significantly reduce the chloride diffusion depth and diffusion coefficient values for both environmental conditions, with a more significant effect on the drying-wetting cycle. The chloride concentration on the surface of slag concrete (SC) in compression zones is greater than that in SC tension zones and that in ordinary concrete (OC) in both tension and compression zones. The study established a prediction model describing the chloride-penetration characteristics of concrete beams subjected to sustained bending moment. The proposed model is a reasonable approach for predicting chloride distribution in reinforced concrete beams with slag addition subjected to bending moments.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41669540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on the exposure test of fly ash (FA) concrete in different environments, chloride diffusion coefficients and main microstructural parameters measured by mercury intrusion porosimetry (MIP) and their time dependent properties were analyzed at first. Then, the effect of FA content on time-dependent chloride diffusivity and microstructural parameters was investigated. Finally, according to the similarity theory and Jaccard coefficient, the similarities of instantaneous chloride diffusion coefficient and main microstructural parameters between two environments were discussed. Results show that the proportion of pores with size ≥100 nm has the best correlation with chloride diffusivity of concrete. Besides, chloride diffusion coefficients and main microstructural parameters both decrease with exposure time. The decreasing rate increases with the increase of FA content. Moreover, in the laboratory environment with high temperature and high salinity, an acceleration effect on chloride diffusion can be observed. Results of similarity analysis indicate that chloride diffusivity and main microstructural parameters at the exposure time of 320 d in the laboratory environment is the most similar to that in site at the exposure time of 840 d. For concrete with FA content not more than 40%, their Jaccard coefficients of similar criterion parameters related to chloride diffusivity and microstructural parameters are all greater than 0.87.
{"title":"Time-dependent similarity and micro-mechanism of chloride diffusivity of fly ash concrete in different environments","authors":"Yurong Zhang, Xueqing Ma, S. Du, Yun Zhang","doi":"10.1680/jmacr.22.00236","DOIUrl":"https://doi.org/10.1680/jmacr.22.00236","url":null,"abstract":"Based on the exposure test of fly ash (FA) concrete in different environments, chloride diffusion coefficients and main microstructural parameters measured by mercury intrusion porosimetry (MIP) and their time dependent properties were analyzed at first. Then, the effect of FA content on time-dependent chloride diffusivity and microstructural parameters was investigated. Finally, according to the similarity theory and Jaccard coefficient, the similarities of instantaneous chloride diffusion coefficient and main microstructural parameters between two environments were discussed. Results show that the proportion of pores with size ≥100 nm has the best correlation with chloride diffusivity of concrete. Besides, chloride diffusion coefficients and main microstructural parameters both decrease with exposure time. The decreasing rate increases with the increase of FA content. Moreover, in the laboratory environment with high temperature and high salinity, an acceleration effect on chloride diffusion can be observed. Results of similarity analysis indicate that chloride diffusivity and main microstructural parameters at the exposure time of 320 d in the laboratory environment is the most similar to that in site at the exposure time of 840 d. For concrete with FA content not more than 40%, their Jaccard coefficients of similar criterion parameters related to chloride diffusivity and microstructural parameters are all greater than 0.87.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41755423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to investigate the bond and anchorage characteristics of steel bars embedded in Ultra-High Performance Concrete (UHPC), Tepfer thick-walled cylinder theory and elastic mechanics theory were used to establish the theoretical calculation model of bond strength between deformed steel bars and UHPC under the conditions of splitting failure and pull-out failure, respectively. Then the proposed calculation model is verified with a large number of test data from the literature and experiments conducted by the author. Finally, the anchorage length of deformed steel bars in UHPC is calculated by Central Point method, Checking Point method and the design specification of normal concrete structure, and the recommended values of anchorage length are given based on anchorage reliability theory. The research results can provide design basis for engineering designers, and are also a useful guideline for the popularization and application of UHPC materials.
{"title":"Theoretical analysis on bond characteristics between steel bars and ultra-high performance concrete","authors":"Aoxiang Hu, Jing Du","doi":"10.1680/jmacr.22.00291","DOIUrl":"https://doi.org/10.1680/jmacr.22.00291","url":null,"abstract":"In order to investigate the bond and anchorage characteristics of steel bars embedded in Ultra-High Performance Concrete (UHPC), Tepfer thick-walled cylinder theory and elastic mechanics theory were used to establish the theoretical calculation model of bond strength between deformed steel bars and UHPC under the conditions of splitting failure and pull-out failure, respectively. Then the proposed calculation model is verified with a large number of test data from the literature and experiments conducted by the author. Finally, the anchorage length of deformed steel bars in UHPC is calculated by Central Point method, Checking Point method and the design specification of normal concrete structure, and the recommended values of anchorage length are given based on anchorage reliability theory. The research results can provide design basis for engineering designers, and are also a useful guideline for the popularization and application of UHPC materials.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45785258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aim of this study was to develop an algebraic equation to calculate the thermal conductivity coefficients of porous solid materials. The components of the equation consisted of material porosity and density, and thermal conductivity coefficients of its Matrix and porous gas. The equation was applied to ten samples of organic sediment stones, volcanic rocks, and porous aggregates. The thermal conductivity coefficients given by the equation were higher than those measured experimentally (6.62%-16.89%). The proposed equation was also compared to six algebraic equations. Results suggest that the proposed algebraic equation can be used to calculate the thermal conductivity coefficients of solid materials containing complex geometrical pores. Highlights • A simple algebraic equation was developed to determine of the effective thermal conductivities of concrete with porous aggregates. • The equation was applied to the concrete with expanded clay, expanded polystyrene, pumice and fly ash aggregates. • The new produced samples can be used as light concrete in building.
{"title":"Modelling for determining the thermal conductivity of porous solid materials","authors":"","doi":"10.1680/jmacr.22.00354","DOIUrl":"https://doi.org/10.1680/jmacr.22.00354","url":null,"abstract":"The aim of this study was to develop an algebraic equation to calculate the thermal conductivity coefficients of porous solid materials. The components of the equation consisted of material porosity and density, and thermal conductivity coefficients of its Matrix and porous gas. The equation was applied to ten samples of organic sediment stones, volcanic rocks, and porous aggregates. The thermal conductivity coefficients given by the equation were higher than those measured experimentally (6.62%-16.89%). The proposed equation was also compared to six algebraic equations. Results suggest that the proposed algebraic equation can be used to calculate the thermal conductivity coefficients of solid materials containing complex geometrical pores. Highlights • A simple algebraic equation was developed to determine of the effective thermal conductivities of concrete with porous aggregates. • The equation was applied to the concrete with expanded clay, expanded polystyrene, pumice and fly ash aggregates. • The new produced samples can be used as light concrete in building.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44466814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, capacitance based self-sensing properties of the cement pastes of different curing time are studied for the first time. 7-day, 14-day and 28-day cement paste samples which do not require any functional materials are tested. Continuous and discontinuous loading cycles (minimum load of 21 kPa, maximum load of 98 kPa) are applied to the cement pastes. It is revealed that capacitance based self-sensing is superior to resistance based self-sensing owing to its greater dependence on stress and reversibility. The capacitance change is irreversible for the 7-day cement paste sample due to irreversible deformation. Over time capacitive self-sensing become more effective. The stress sensitivity (fractional increase in capacitance divided by stress) for the 28-day cement paste sample is 2.54 x10−8/Pa. It is also revealed that with an increase in hydration time, decreases in capacitance values are observed, which shows that the strength increase in cement paste can also be sensed with capacitance measurement.
{"title":"Capacitance-based compression self-sensing effectiveness of cement paste with curing time","authors":"","doi":"10.1680/jmacr.22.00114","DOIUrl":"https://doi.org/10.1680/jmacr.22.00114","url":null,"abstract":"In this study, capacitance based self-sensing properties of the cement pastes of different curing time are studied for the first time. 7-day, 14-day and 28-day cement paste samples which do not require any functional materials are tested. Continuous and discontinuous loading cycles (minimum load of 21 kPa, maximum load of 98 kPa) are applied to the cement pastes. It is revealed that capacitance based self-sensing is superior to resistance based self-sensing owing to its greater dependence on stress and reversibility. The capacitance change is irreversible for the 7-day cement paste sample due to irreversible deformation. Over time capacitive self-sensing become more effective. The stress sensitivity (fractional increase in capacitance divided by stress) for the 28-day cement paste sample is 2.54 x10−8/Pa. It is also revealed that with an increase in hydration time, decreases in capacitance values are observed, which shows that the strength increase in cement paste can also be sensed with capacitance measurement.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42637808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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