Synopsis: Restrained tests are used to evaluate the risk of early age cracking and the cracking sensitivity of concrete mixtures. One test that has become common in recent years is the active uniaxial restrained test in which the length change due to shrinkage is recovered by applying external load to maintain the concrete sample at constant length. The length change is measured by linear variable differential transformer (LVDT), which is used as the control signal in this test. In such tests, the dog-bone geometry is used to grip the ends. To ensure a fully restrained test, the LVDT response to the loads and to shrinkage should reflect the deformation in the concrete sample. Therefore, the grip-specimen interaction should not interfere with the measurement of deformation, and this depends on the instrumentation and how the LVDT is attached to the concrete specimen. Some experiments in the literature have the LVDT attached to the steel grips, a practice vulnerable to possible error due to the interaction between the grip and the concrete. This study considered two methods of attaching the LVDT. First, the LVDT is attached to the steel grips; second, the LVDT is attached to the concrete within the zone of reduced cross-section. The results indicate that attaching the LVDT to the grips results in errant measurement of the shrinkage stress, creep, and elastic strains due to the grip-specimen interaction. The consequences will be false interpretation of fully restrained shrinkage and creep characteristics because the grip-specimen interaction leads to a partially restrained test. The study suggests mounting the LVDT to the concrete sample away from the grips to achieve a fully restrained test. Results for two concrete mixtures with w/c ratio of 0.51 and 0.56 are discussed for both methods of attaching LVDTs.
{"title":"Grip-Specimen Interaction in Uniaxial Restrained Test","authors":"S. Altoubat, D. Lange","doi":"10.14359/12253","DOIUrl":"https://doi.org/10.14359/12253","url":null,"abstract":"Synopsis: Restrained tests are used to evaluate the risk of early age cracking and the cracking sensitivity of concrete mixtures. One test that has become common in recent years is the active uniaxial restrained test in which the length change due to shrinkage is recovered by applying external load to maintain the concrete sample at constant length. The length change is measured by linear variable differential transformer (LVDT), which is used as the control signal in this test. In such tests, the dog-bone geometry is used to grip the ends. To ensure a fully restrained test, the LVDT response to the loads and to shrinkage should reflect the deformation in the concrete sample. Therefore, the grip-specimen interaction should not interfere with the measurement of deformation, and this depends on the instrumentation and how the LVDT is attached to the concrete specimen. Some experiments in the literature have the LVDT attached to the steel grips, a practice vulnerable to possible error due to the interaction between the grip and the concrete. This study considered two methods of attaching the LVDT. First, the LVDT is attached to the steel grips; second, the LVDT is attached to the concrete within the zone of reduced cross-section. The results indicate that attaching the LVDT to the grips results in errant measurement of the shrinkage stress, creep, and elastic strains due to the grip-specimen interaction. The consequences will be false interpretation of fully restrained shrinkage and creep characteristics because the grip-specimen interaction leads to a partially restrained test. The study suggests mounting the LVDT to the concrete sample away from the grips to achieve a fully restrained test. Results for two concrete mixtures with w/c ratio of 0.51 and 0.56 are discussed for both methods of attaching LVDTs.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125787192","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}
The paper reviews the opportunities the Portland Cement Association has taken to address part of the education needs of the cement and concrete industries. Addressed are current educational efforts and a review of how research at universities addresses both the educational and technical needs of the industry. A list of concrete related websites is included. Through education the concrete industry can meet the need for informed professionals who are necessary to sustain concrete as the building material of choice for this century.
{"title":"The Education Connection: From Research to the Web","authors":"S. Kosmatka","doi":"10.14359/12274","DOIUrl":"https://doi.org/10.14359/12274","url":null,"abstract":"The paper reviews the opportunities the Portland Cement Association has taken to address part of the education needs of the cement and concrete industries. Addressed are current educational efforts and a review of how research at universities addresses both the educational and technical needs of the industry. A list of concrete related websites is included. Through education the concrete industry can meet the need for informed professionals who are necessary to sustain concrete as the building material of choice for this century.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122829215","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}
The paper reviews the investigation of the bond stress versus slip behavior of steel fibers cut from twisted wire strands; the behavior is then compared to that of a single triangular steel fiber twisted along its axis. The parameters investigated are: the embedded length of the fiber in the matrix; the number of individual wires making a strand fiber; the pitch distance of the fiber; the compressive strength of the mortar matrix; and the tensile strength of the fiber.
{"title":"Evaluation of Bond-Slip Behavior of Twisted Wire Strand Steel Fibers Embedded in Cement Matrix","authors":"C. Sujivorakul, A. Naaman","doi":"10.14359/12258","DOIUrl":"https://doi.org/10.14359/12258","url":null,"abstract":"The paper reviews the investigation of the bond stress versus slip behavior of steel fibers cut from twisted wire strands; the behavior is then compared to that of a single triangular steel fiber twisted along its axis. The parameters investigated are: the embedded length of the fiber in the matrix; the number of individual wires making a strand fiber; the pitch distance of the fiber; the compressive strength of the mortar matrix; and the tensile strength of the fiber.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132195195","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}
The two separate structures of the Kishwaukee River Bridge in Rockford, Illinois, opened to traffic in 1980 (the southbound bridge) and 1982 (the northbound bridge). Severe cracking in the webs is evident, as eight segments on either side of each pier are heavily cracked. The paper describes the model that was developed for assessment of stresses in shear reinforcement based on measured crack width. The model is based on CFB-FIP model for crack width prediction that was modified for inclined cracks.
{"title":"Assessment of Stresses in Reinforcement of Kishwaukee River Bridge","authors":"J. Halvonik, M. W. Wang","doi":"10.14359/12248","DOIUrl":"https://doi.org/10.14359/12248","url":null,"abstract":"The two separate structures of the Kishwaukee River Bridge in Rockford, Illinois, opened to traffic in 1980 (the southbound bridge) and 1982 (the northbound bridge). Severe cracking in the webs is evident, as eight segments on either side of each pier are heavily cracked. The paper describes the model that was developed for assessment of stresses in shear reinforcement based on measured crack width. The model is based on CFB-FIP model for crack width prediction that was modified for inclined cracks.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126092255","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}
The paper presents and discusses results from flexural fatigue tests on plain concrete and two fiber reinforced concrete (FRC) mixes. The fatigue performance of both the FRC mixes investigated in the study were superior to that of the control mix. The difference between the FRC mixes and the control mix becomes readily apparent at the higher levels of upper limit of fatigue stress. The three stage process that characterizes the fatigue failure in FRC is discussed.
{"title":"Fatigue Characteristics of Fiber Reinforced Concrete for Pavement Applications","authors":"V. Gopalaratnam, T. Cherian","doi":"10.14359/12247","DOIUrl":"https://doi.org/10.14359/12247","url":null,"abstract":"The paper presents and discusses results from flexural fatigue tests on plain concrete and two fiber reinforced concrete (FRC) mixes. The fatigue performance of both the FRC mixes investigated in the study were superior to that of the control mix. The difference between the FRC mixes and the control mix becomes readily apparent at the higher levels of upper limit of fatigue stress. The three stage process that characterizes the fatigue failure in FRC is discussed.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129453228","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}
The paper evaluates the use of extrusion technology for the production of cement boards with unbleached kraft pulps. The experiment fabricated cement boards reinforced by both hardwood and softwood pulp of different percentages by using an auger type lab extruded. The moisture content, water absorption and density of all batches were measured. To investigate the strength, the toughness, the anisotropy, the age effect and the resistance to natural weathering as well as the freeze-thaw cycling, the flexural response of the cement boards was used.
{"title":"\"Strength, Toughness and Durability of Extruded Cement Boards with Unbleached Kraft Pulp\"","authors":"Y. Shao, S. Moras","doi":"10.14359/12268","DOIUrl":"https://doi.org/10.14359/12268","url":null,"abstract":"The paper evaluates the use of extrusion technology for the production of cement boards with unbleached kraft pulps. The experiment fabricated cement boards reinforced by both hardwood and softwood pulp of different percentages by using an auger type lab extruded. The moisture content, water absorption and density of all batches were measured. To investigate the strength, the toughness, the anisotropy, the age effect and the resistance to natural weathering as well as the freeze-thaw cycling, the flexural response of the cement boards was used.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122620768","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}
{"title":"Influence of Superplasticizer oin the Volume Stability of Hydrating Cement Pastes at an Early Age","authors":"B. Bissonnette, J. Marchand, C. Martel, M. Pigeon","doi":"10.14359/12252","DOIUrl":"https://doi.org/10.14359/12252","url":null,"abstract":"","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131271400","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}
{"title":"Failure Mechanism of Reinforced Concrete Under Cyclic Loading","authors":"T. Hsu, M. Mansour","doi":"10.14359/12242","DOIUrl":"https://doi.org/10.14359/12242","url":null,"abstract":"","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127491399","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}
The paper reviews an experimental study conducted to evaluate the restrained shrinkage in plain and fiber reinforced concrete. A constant humidity chamber was used to hold the restrained shrinkage specimens. While the chamber was subjected to constant flow of air around the specimens, the strain in the restraining steel and the crack width in the concrete samples were monitored continuously. An analytical approach was developed in order to better understand the restrained shrinkage of concrete under the proposed test method and to eliminate the influence of test conditions. The model incorporates key influential parameters of shrinkage, creep, aging, and microcracking, in stress analysis of a restrained concrete section.
{"title":"Modeling of Restrained Shrinkage Cracking in Concrete Materials","authors":"S. Mane, T. Desai, D. Kingsbury, B. Mobasher","doi":"10.14359/12255","DOIUrl":"https://doi.org/10.14359/12255","url":null,"abstract":"The paper reviews an experimental study conducted to evaluate the restrained shrinkage in plain and fiber reinforced concrete. A constant humidity chamber was used to hold the restrained shrinkage specimens. While the chamber was subjected to constant flow of air around the specimens, the strain in the restraining steel and the crack width in the concrete samples were monitored continuously. An analytical approach was developed in order to better understand the restrained shrinkage of concrete under the proposed test method and to eliminate the influence of test conditions. The model incorporates key influential parameters of shrinkage, creep, aging, and microcracking, in stress analysis of a restrained concrete section.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128901670","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}
The aim of this paper is to review briefly the current position of fracture mechanics in concrete applications. The possible future developments are also discussed.
本文的目的是简要回顾断裂力学在混凝土应用中的现状。并对未来可能的发展进行了讨论。
{"title":"Applications of Fracture Mechanics to Concrete: Where Do We Go From Here?","authors":"S. Mindess","doi":"10.14359/12270","DOIUrl":"https://doi.org/10.14359/12270","url":null,"abstract":"The aim of this paper is to review briefly the current position of fracture mechanics in concrete applications. The possible future developments are also discussed.","PeriodicalId":265574,"journal":{"name":"SP-206: Concrete: Material Science to Application - A Tribute to Surendra P. Shah","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131528935","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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