Dry crushed rock fines (CRF) which is a nuisance waste at crushed rock aggregate plants has been investigated for its use as a mineral addition in concrete. According to the research conducted so far, both methylene-blue test and sand equivalent test can be applied for the screening test on the quality of CRF. Furthermore, CRF is useful not only as supplemental fines in fine particle lacking aggregates such as sea-dredged sand, but also for high-volume fines in self-compacting concrete. This paper presents the test results of a prototype reinforced concrete column and wall structure cast with self-compacting concrete (SCC) containing high-volume of CRF (CRFSCC). Judging from the test results of concrete cores obtained from the column and wall of the structure, the following conclusions were obtained: (1) The greater the distance the concrete flowed through reinforcing steel bars, the greater the segregation of the CRFSCC; (2) Both the front part of the CRFSCC flow and upper part of the CRFSCC structure contained less amount of coarse aggregate, and showed both low values for modulus of elasticity and high values for drying shrinkage; (3) In order to get more homogeneous quality in the structure with CRFSCC, special care is needed for concrete casting procedures - it is suggested that a reverse casting flow direction technique may be effective; and (4) Drying shrinkage of CRFSCC did not result in deleterious cracking on the structure.
{"title":"Self-Compacting Concrete With High-Volume Crushed Rock Fines","authors":"A. Nishio, H. Tamura, M. Ohashi","doi":"10.14359/6064","DOIUrl":"https://doi.org/10.14359/6064","url":null,"abstract":"Dry crushed rock fines (CRF) which is a nuisance waste at crushed rock aggregate plants has been investigated for its use as a mineral addition in concrete. According to the research conducted so far, both methylene-blue test and sand equivalent test can be applied for the screening test on the quality of CRF. Furthermore, CRF is useful not only as supplemental fines in fine particle lacking aggregates such as sea-dredged sand, but also for high-volume fines in self-compacting concrete. This paper presents the test results of a prototype reinforced concrete column and wall structure cast with self-compacting concrete (SCC) containing high-volume of CRF (CRFSCC). Judging from the test results of concrete cores obtained from the column and wall of the structure, the following conclusions were obtained: (1) The greater the distance the concrete flowed through reinforcing steel bars, the greater the segregation of the CRFSCC; (2) Both the front part of the CRFSCC flow and upper part of the CRFSCC structure contained less amount of coarse aggregate, and showed both low values for modulus of elasticity and high values for drying shrinkage; (3) In order to get more homogeneous quality in the structure with CRFSCC, special care is needed for concrete casting procedures - it is suggested that a reverse casting flow direction technique may be effective; and (4) Drying shrinkage of CRFSCC did not result in deleterious cracking on the structure.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"397 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126754108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thin-section petrography, coupled with quantitative electron-probe microanalysis (EPMA), is very useful in identifying reactive constituents and alkali-aggregate reaction in concretes, as well as in characterizing the nature of cement constituents, reaction products and gel products in old deteriorated concretes. EPMA analysis made it possible to detect chemical compositions of the unhydrated cement phases alite, belite, tricalcium aluminate, and the ferrite phase in the original cement used in old structures from Canada and Japan, made even 100 years ago. Coupled with detailed petrography in thin section, this technique also enabled us to estimate the thermal histories and composition of cement clinkers in hardened concretes, variations of CSH gels which reflect the degree of cement hydration, leaching and weathering of concretes, as well as the process of migration and alteration of ASR gels in concretes. The results thus obtained can be used for the assessment of cement properties and the durability of old concretes.
{"title":"Petrographic Diagnosis of Alkali-Aggregate Reaction in Concrete Based on Quantitative EPMA Analysis","authors":"T. Katayama","doi":"10.14359/6060","DOIUrl":"https://doi.org/10.14359/6060","url":null,"abstract":"Thin-section petrography, coupled with quantitative electron-probe microanalysis (EPMA), is very useful in identifying reactive constituents and alkali-aggregate reaction in concretes, as well as in characterizing the nature of cement constituents, reaction products and gel products in old deteriorated concretes. EPMA analysis made it possible to detect chemical compositions of the unhydrated cement phases alite, belite, tricalcium aluminate, and the ferrite phase in the original cement used in old structures from Canada and Japan, made even 100 years ago. Coupled with detailed petrography in thin section, this technique also enabled us to estimate the thermal histories and composition of cement clinkers in hardened concretes, variations of CSH gels which reflect the degree of cement hydration, leaching and weathering of concretes, as well as the process of migration and alteration of ASR gels in concretes. The results thus obtained can be used for the assessment of cement properties and the durability of old concretes.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129133208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Ogasawara, H. Naito, T. Miura, T. Abe, R. Ohmura
Recently, application of super-workable concrete with high flowability, has been increasing in the construction of steel-concrete composite structures of sandwich systems, concrete-filled steel tubes, and structures with congested reinforcing bar arrangements, since compacting of concrete is difficult in those kinds of structures. In such cases, it is necessary to avoid impairing integrities of the structures as a result of gaps formed between steel and concrete due to subsidence and shrinkage of concrete and cracks formed due to restraint by steel. In this study, the influences of the kinds of cement and admixtures, and differences of addition rates on autogenous shrinkage, drying shrinkage, and subsidence of super-workable concrete are examined, as are the influences on gaps formed under disphragms in concrete as well. As a result, it is found that shrinkage and subsidence behaviors differ considerably depending on the kinds of concrete and admixtures.
{"title":"Study on Subsidence and Shrinkage of Super-Workable Concrete","authors":"T. Ogasawara, H. Naito, T. Miura, T. Abe, R. Ohmura","doi":"10.14359/6065","DOIUrl":"https://doi.org/10.14359/6065","url":null,"abstract":"Recently, application of super-workable concrete with high flowability, has been increasing in the construction of steel-concrete composite structures of sandwich systems, concrete-filled steel tubes, and structures with congested reinforcing bar arrangements, since compacting of concrete is difficult in those kinds of structures. In such cases, it is necessary to avoid impairing integrities of the structures as a result of gaps formed between steel and concrete due to subsidence and shrinkage of concrete and cracks formed due to restraint by steel. In this study, the influences of the kinds of cement and admixtures, and differences of addition rates on autogenous shrinkage, drying shrinkage, and subsidence of super-workable concrete are examined, as are the influences on gaps formed under disphragms in concrete as well. As a result, it is found that shrinkage and subsidence behaviors differ considerably depending on the kinds of concrete and admixtures.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134151114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper deals with various types of silanes (alcohol or water solvent, polymerization degree) and silane systems, which are typical hydrophobic agents as repair materials. From the viewpoint of the deterioration mechanism, water control in concrete structures is one of the most important repair strategies. Therefore, various types of surface treatments which can control water content in concrete structures are applied for repair work. Silanes and silane systems were one of the most important for hydrophobic treatment. In this study, the effect of various types of silanes and silane treatment systems on the hydrophobicity of treated concrete is investigated. Furthermore, water control property in concrete treated with silane system is discussed.
{"title":"Water Control Properties of Silane Treatment","authors":"Y. Kubo, A. Hattori, T. Miyagawa, K. Hori","doi":"10.14359/6043","DOIUrl":"https://doi.org/10.14359/6043","url":null,"abstract":"This paper deals with various types of silanes (alcohol or water solvent, polymerization degree) and silane systems, which are typical hydrophobic agents as repair materials. From the viewpoint of the deterioration mechanism, water control in concrete structures is one of the most important repair strategies. Therefore, various types of surface treatments which can control water content in concrete structures are applied for repair work. Silanes and silane systems were one of the most important for hydrophobic treatment. In this study, the effect of various types of silanes and silane treatment systems on the hydrophobicity of treated concrete is investigated. Furthermore, water control property in concrete treated with silane system is discussed.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133899610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Maréchal, B. Gérard, J. Marchand, J. Gagnon, O. Didry
In the past decades, cement-based materials have been increasingly used for the construction of radioactive-waste barriers. The design of durable structures for this specific application requires a precise knowledge of the evolution of the material engineering properties over a 1000-year period. Among the wide range of degradation phenomena to which the structure can be exposed during its service life, the leaching of calcium appears to be the most critical. Given the intricate nature of the leaching process, a reliable prediction of the long term behavior of the concrete barriers can only be made through numerical modeling. In order to generate more quantitative information on the subject, a new accelerated leaching test has been developed. The operating principle of the test is quite simple. The leaching process is accelerated by applying an external electric field through the material. This paper details the different electrochemical phenomena involved during a LIFT experiment. It also presents experimental data obtained for various neat paste samples. In this series of tests, the evolution of the hydrated cement paste microstructure was studied using various experimental techniques, such as X-ray diffraction, DTA/TG analyses and scanning electron microscopy. The advantages and limitations of this new procedure are discussed.
{"title":"New Accelerated Leaching Experiment: The LIFT Procedure","authors":"J. Maréchal, B. Gérard, J. Marchand, J. Gagnon, O. Didry","doi":"10.14359/6081","DOIUrl":"https://doi.org/10.14359/6081","url":null,"abstract":"In the past decades, cement-based materials have been increasingly used for the construction of radioactive-waste barriers. The design of durable structures for this specific application requires a precise knowledge of the evolution of the material engineering properties over a 1000-year period. Among the wide range of degradation phenomena to which the structure can be exposed during its service life, the leaching of calcium appears to be the most critical. Given the intricate nature of the leaching process, a reliable prediction of the long term behavior of the concrete barriers can only be made through numerical modeling. In order to generate more quantitative information on the subject, a new accelerated leaching test has been developed. The operating principle of the test is quite simple. The leaching process is accelerated by applying an external electric field through the material. This paper details the different electrochemical phenomena involved during a LIFT experiment. It also presents experimental data obtained for various neat paste samples. In this series of tests, the evolution of the hydrated cement paste microstructure was studied using various experimental techniques, such as X-ray diffraction, DTA/TG analyses and scanning electron microscopy. The advantages and limitations of this new procedure are discussed.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131585796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the effects of various curing methods in cold weather conditions on the compressive strength of concrete incorporating ground granulated blast-furnace slag (GGBS). The specific surface area of GGBS (4000, 6000, and 8000 sq cm/g) was varied, as was the replacement level of cement by GGBS (50, 60, 70, and 80%). Mortar specimens were prepared for the experiment. The specimens were cured at 5 deg C constant and 20 deg C constant by atmospheric curing, water curing and sealed curing. Compressive strength test results were performed at various ages. Furthermore, the effects of applying heat curing at 30 deg C constant at early age to GGBS-concrete on the strength development were also examined. Results show the concrete incorporating the GGBS with the specific surface area of 8000 sq cm/g would have no strength development problem even though it were cured at 5 deg C by sealed curing. However, heat curing may have a bad influence on the strength development, particularly at later ages. On the other hand, GGBS-concrete with the specific surface area of 4000 sq cm/g would require heat curing in order to improve the compressive strength at early ages. Finally, based on the data derived from this experiment, the relationship between the compressive strength of concrete incorporating GGBS and maturity is discussed.
{"title":"Effects of Curing Methods in Cold Regions on Strength of Concrete Incorporating Ground Granulated Blast Furnace Slag","authors":"T. Miura, I. Iwaki","doi":"10.14359/6075","DOIUrl":"https://doi.org/10.14359/6075","url":null,"abstract":"This paper investigates the effects of various curing methods in cold weather conditions on the compressive strength of concrete incorporating ground granulated blast-furnace slag (GGBS). The specific surface area of GGBS (4000, 6000, and 8000 sq cm/g) was varied, as was the replacement level of cement by GGBS (50, 60, 70, and 80%). Mortar specimens were prepared for the experiment. The specimens were cured at 5 deg C constant and 20 deg C constant by atmospheric curing, water curing and sealed curing. Compressive strength test results were performed at various ages. Furthermore, the effects of applying heat curing at 30 deg C constant at early age to GGBS-concrete on the strength development were also examined. Results show the concrete incorporating the GGBS with the specific surface area of 8000 sq cm/g would have no strength development problem even though it were cured at 5 deg C by sealed curing. However, heat curing may have a bad influence on the strength development, particularly at later ages. On the other hand, GGBS-concrete with the specific surface area of 4000 sq cm/g would require heat curing in order to improve the compressive strength at early ages. Finally, based on the data derived from this experiment, the relationship between the compressive strength of concrete incorporating GGBS and maturity is discussed.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"166 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129356759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the results of an investigation to determine the performance characteristics of concrete made with recycled coarse aggregate from a plant. Slump and air content of fresh recycled aggregate concrete are studied. The compressive strength, drying shrinkage and resistance to freezing and thawing were investigated experimentally when the types and combinations of coarse aggregate, admixture, air content and so on were varied. It was found that the recycled aggregate concrete decreased the compressive strength at 7 to 28 days as compared with those properties of the control concrete. The decrease in strength can be suppressed low by partial use of recycled coarse aggregate. Drying shrinkage of recycled aggregate concrete showed larger value than conventional crushed aggregate concrete. The use of shrinkage reducing agent can reduce the drying shrinkage of recycled aggregate concrete. The resistance to freezing and thawing of recycled aggregate concrete was lower than that of control concrete of similar composition. The decrease in resistance to freezing and thawing can be suppressed low by partial use of recycled aggregate, reducing the water cement ratio and increasing entraining air.
{"title":"\"Mechanical Properties, Drying Shrinkage and Resistance to Freezing and Thawing of Concrete Using Recycled Aggregate\"","authors":"T. Yamato, Y. Emoto, M. Soeda","doi":"10.14359/6034","DOIUrl":"https://doi.org/10.14359/6034","url":null,"abstract":"This paper presents the results of an investigation to determine the performance characteristics of concrete made with recycled coarse aggregate from a plant. Slump and air content of fresh recycled aggregate concrete are studied. The compressive strength, drying shrinkage and resistance to freezing and thawing were investigated experimentally when the types and combinations of coarse aggregate, admixture, air content and so on were varied. It was found that the recycled aggregate concrete decreased the compressive strength at 7 to 28 days as compared with those properties of the control concrete. The decrease in strength can be suppressed low by partial use of recycled coarse aggregate. Drying shrinkage of recycled aggregate concrete showed larger value than conventional crushed aggregate concrete. The use of shrinkage reducing agent can reduce the drying shrinkage of recycled aggregate concrete. The resistance to freezing and thawing of recycled aggregate concrete was lower than that of control concrete of similar composition. The decrease in resistance to freezing and thawing can be suppressed low by partial use of recycled aggregate, reducing the water cement ratio and increasing entraining air.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"04 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130807965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Penetration of aggressive ions, such as chlorides, through concrete is one of the factors which causes the depassivation of reinforcement and therefore may shorten the service life of a reinforced concrete structure. Most research work focusing on natural or accelerated diffusion tests generally relies on the validity of Fick's laws. In this paper, we present both a new accelerated diffusion cell and an original test operating mode. The theoretical approach is based upon the study of diffusion-migration mechanism within the pore solution. The experimental results presented here have been obtained with tests on samples of saturated mortar.
{"title":"Accelerated Testing of Chloride Diffusivity in Cement Based Materials: New Test Operating Mode","authors":"A. Ammar, J. Loche, P. Dumargue","doi":"10.14359/6062","DOIUrl":"https://doi.org/10.14359/6062","url":null,"abstract":"Penetration of aggressive ions, such as chlorides, through concrete is one of the factors which causes the depassivation of reinforcement and therefore may shorten the service life of a reinforced concrete structure. Most research work focusing on natural or accelerated diffusion tests generally relies on the validity of Fick's laws. In this paper, we present both a new accelerated diffusion cell and an original test operating mode. The theoretical approach is based upon the study of diffusion-migration mechanism within the pore solution. The experimental results presented here have been obtained with tests on samples of saturated mortar.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121481105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A computer controlled temperature matched curing system to simulate curing of concrete in structures is presented. The system has capability to accurately control the ambient temperature against the hydration temperature generated by a fully insulated concrete specimen. It is also capable of simulating any cooling rate which might occur on site and which depends on the thickness of the concrete element, the type of formwork, the ambient temperature, humidity and wind velocity. Data on normal portland cement concrete and fly ash concrete of different compositions cured at 5 deg C, 20 deg C and 35 deg C are compared with data on concrete cured using semiadiabatic conditions, and the effect of simulating the cooling-time curve is discussed in light of the results on strength, porosity and permeability.
{"title":"Effect of Curing Temperature on the Strength and Performance Properties of Concrete","authors":"J. Cabrera, B. A. Gaafar","doi":"10.14359/6076","DOIUrl":"https://doi.org/10.14359/6076","url":null,"abstract":"A computer controlled temperature matched curing system to simulate curing of concrete in structures is presented. The system has capability to accurately control the ambient temperature against the hydration temperature generated by a fully insulated concrete specimen. It is also capable of simulating any cooling rate which might occur on site and which depends on the thickness of the concrete element, the type of formwork, the ambient temperature, humidity and wind velocity. Data on normal portland cement concrete and fly ash concrete of different compositions cured at 5 deg C, 20 deg C and 35 deg C are compared with data on concrete cured using semiadiabatic conditions, and the effect of simulating the cooling-time curve is discussed in light of the results on strength, porosity and permeability.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"186 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134394326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many reinforced buildings were damaged by the Hygoken-Nanbu Earthquake of 1995. In order to clarify the actual state of carbonation of the concrete and the chloride ion content in concrete of buildings in the Hanshin area, the depths of carbonation and the amount of chloride ion were measured in 117 concrete samples that were obtained from 97 damaged buildings. The effects of carbonation depth and chloride ion content with regard to the corrosion of steel were also investigated. The measured carbonation depths were wildly scattered, with some of the concrete being heavily carbonated. The amounts of chloride ions in old river sand concrete were small. Large amounts of chloride ion were found mixed with sand, that came not only from the ocean but also from rivers, in the buildings that were built between 1960 and 1978. This chloride ion was thought to be induced through sea sand and an admixture. The concentration of chloride ions in concrete were small for buildings that had been constructed after the regulation of the amount of chloride in concrete that was instituted in 1986. A great deal of the steel embedded in the carbonated concrete was severely corroded. The degree of steel corrosion tended to increase with an increase in the amount of chloride ion as well as carbonation depth.
{"title":"\"Carbonation, Amount of Chloride Ion, and Corrosion of Steel Reinforced Concrete Buildings in HANSHIN Region\"","authors":"Y. Ohno, Y. Yamamoto","doi":"10.14359/6047","DOIUrl":"https://doi.org/10.14359/6047","url":null,"abstract":"Many reinforced buildings were damaged by the Hygoken-Nanbu Earthquake of 1995. In order to clarify the actual state of carbonation of the concrete and the chloride ion content in concrete of buildings in the Hanshin area, the depths of carbonation and the amount of chloride ion were measured in 117 concrete samples that were obtained from 97 damaged buildings. The effects of carbonation depth and chloride ion content with regard to the corrosion of steel were also investigated. The measured carbonation depths were wildly scattered, with some of the concrete being heavily carbonated. The amounts of chloride ions in old river sand concrete were small. Large amounts of chloride ion were found mixed with sand, that came not only from the ocean but also from rivers, in the buildings that were built between 1960 and 1978. This chloride ion was thought to be induced through sea sand and an admixture. The concentration of chloride ions in concrete were small for buildings that had been constructed after the regulation of the amount of chloride in concrete that was instituted in 1986. A great deal of the steel embedded in the carbonated concrete was severely corroded. The degree of steel corrosion tended to increase with an increase in the amount of chloride ion as well as carbonation depth.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134593710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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