The void diameter and the internal surface area of porous concrete, prepared with crushed stone and glass balls of differing diameters as aggregate, were determined by slicing off the central cross section, cutting it into pieces at constant intervals and making an image analysis of those sections to examine the effect of the analytical results on the physical properties of the porous concrete and the growth of plants. The results indicated that the mean void diameter of the porous concrete is approximately 0.22 to 0.24 times the particle diameter of the aggregate packed with 30% binder and that the interconnected void, approximately 3 mm in mean diameter, is appropriate for grass-planting concrete.
{"title":"Properties and Application of Environmentally Friendly Porous Concrete","authors":"M. Tamai, T. Matsukawa","doi":"10.14359/6035","DOIUrl":"https://doi.org/10.14359/6035","url":null,"abstract":"The void diameter and the internal surface area of porous concrete, prepared with crushed stone and glass balls of differing diameters as aggregate, were determined by slicing off the central cross section, cutting it into pieces at constant intervals and making an image analysis of those sections to examine the effect of the analytical results on the physical properties of the porous concrete and the growth of plants. The results indicated that the mean void diameter of the porous concrete is approximately 0.22 to 0.24 times the particle diameter of the aggregate packed with 30% binder and that the interconnected void, approximately 3 mm in mean diameter, is appropriate for grass-planting concrete.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"11 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":"125657751","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}
Y. Dosho, M. Kikuchi, M. Narikawa, A. Ohshima, A. Kôyama, T. Miura
A study on the application of recycled concrete for structural concrete was carried out under the concept of life cycle assessment (LCA) for environmental management of construction utilizing recycled products. Such products are often discarded, when existing electric power plants are rebuilt or upgraded in order to meet increasing power demands. In pursuing the reuse of these recycled materials, the basic policy was composed of three items: (1) the assurance of quality; (2) the reduction of environmental impact; and (3) construction cost. The study is divided into two main parts: feasibility study on the reuse of recycled concrete, and experimental study on the quality of recycled aggregate and recycled aggregate concrete. This paper presents the result of the experimental study on the quality of recycled aggregate and recycled aggregate concrete. Based on the investigation and the analysis of results, valuable data were obtained regarding concept and practice as to the reuse of construction debris based on LCA.
{"title":"Application of Recycled Concrete for Structural Concrete- Experimental Study on the Quality of Recycled Aggregate and Recycled Aggregate Concrete","authors":"Y. Dosho, M. Kikuchi, M. Narikawa, A. Ohshima, A. Kôyama, T. Miura","doi":"10.14359/6087","DOIUrl":"https://doi.org/10.14359/6087","url":null,"abstract":"A study on the application of recycled concrete for structural concrete was carried out under the concept of life cycle assessment (LCA) for environmental management of construction utilizing recycled products. Such products are often discarded, when existing electric power plants are rebuilt or upgraded in order to meet increasing power demands. In pursuing the reuse of these recycled materials, the basic policy was composed of three items: (1) the assurance of quality; (2) the reduction of environmental impact; and (3) construction cost. The study is divided into two main parts: feasibility study on the reuse of recycled concrete, and experimental study on the quality of recycled aggregate and recycled aggregate concrete. This paper presents the result of the experimental study on the quality of recycled aggregate and recycled aggregate concrete. Based on the investigation and the analysis of results, valuable data were obtained regarding concept and practice as to the reuse of construction debris based on LCA.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"78 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":"130387625","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}
In this paper, the authors present results of an experimental program carried out to study the pull-out behavior of a new type of high yield strength steel deformed reinforcing bars (f sub y = 830 MPa) embedded in high strength concrete (f sub c = 100 MPa). Influence of embedded length, concrete strength and yield steel strength on bond strength has been investigated by means of pull-out tests. The final aim of this research program is to define design and specification requirements for this new material. Variations of the average ultimate bond strength with embedded length, for concretes with compressive strength from 40 MPa to 100 MPa, produce horizontal curves, which indicates that the mean ultimate bond stress is an appropriate bond strength indicator. Ultimate bond strength increases proportionally with both the increase of tensile strength and compressive strength of concrete. No significant effect of the yield steel strength of reinforcement on the value of the mean ultimate bond stress has been observed. In the case of a pull-out failure, the relationships between the ultimate mean bond stress and the main characteristics of the bond between steel and concrete (embedded length, mechanical strengths of concrete and yield steel strength) are similar to the ones of standard deformed reinforcement (f sub y = 500 MPa).
本文介绍了一种新型高屈服强度钢变形钢筋(f sub - y = 830 MPa)嵌入高强度混凝土(f sub - c = 100 MPa)的拉拔性能试验程序的研究结果。通过拉拔试验，研究了埋置长度、混凝土强度和屈服钢强度对粘结强度的影响。这项研究计划的最终目的是确定这种新材料的设计和规格要求。在抗压强度为40 ~ 100 MPa的混凝土中，平均粘结极限应力随埋深的变化呈水平曲线，表明平均粘结极限应力是一个合适的粘结强度指标。极限粘结强度随混凝土抗拉强度和抗压强度的增加而成比例增大。钢筋屈服钢强度对平均极限粘结应力值无显著影响。在拉出破坏情况下，钢与混凝土粘结的主要特征(埋置长度、混凝土机械强度和屈服钢强度)与极限平均粘结应力之间的关系与标准变形钢筋(f下标y = 500 MPa)相似。
{"title":"Pull-Out Behavior of High Yield Strength Steel Deformed Bars Embedded in High Strength Concrete","authors":"M. Lorrain, O. Maurel","doi":"10.14359/6083","DOIUrl":"https://doi.org/10.14359/6083","url":null,"abstract":"In this paper, the authors present results of an experimental program carried out to study the pull-out behavior of a new type of high yield strength steel deformed reinforcing bars (f sub y = 830 MPa) embedded in high strength concrete (f sub c = 100 MPa). Influence of embedded length, concrete strength and yield steel strength on bond strength has been investigated by means of pull-out tests. The final aim of this research program is to define design and specification requirements for this new material. Variations of the average ultimate bond strength with embedded length, for concretes with compressive strength from 40 MPa to 100 MPa, produce horizontal curves, which indicates that the mean ultimate bond stress is an appropriate bond strength indicator. Ultimate bond strength increases proportionally with both the increase of tensile strength and compressive strength of concrete. No significant effect of the yield steel strength of reinforcement on the value of the mean ultimate bond stress has been observed. In the case of a pull-out failure, the relationships between the ultimate mean bond stress and the main characteristics of the bond between steel and concrete (embedded length, mechanical strengths of concrete and yield steel strength) are similar to the ones of standard deformed reinforcement (f sub y = 500 MPa).","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"155 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":"134347675","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}
Portland cement contains sulfur compounds from the clinker phase and from added calcium sulfate (e.g., gypsum) which acts as a set regulator. The purpose of this investigation was to study the influence of the sulfate content in the clinker phase on the performance of superplasticized concrete mixtures in terms of initial slump level at a given water-cement ratio (0.45), slump-loss rate, and compressive strength at early and later ages. Two batches (A and B) of clinker from the same kiln source were studied, the main difference being the content of sulfate (SO3) in the clinker (0.72% and 1.40%, respectively). Different percentages of natural gypsum, as wet regulator, were interground in a laboratory mill to manufacture portland cements: A1, A2, A3 from clinker A, and B1, B2, B3 from clinker B. Three levels of total sulfate content in terms of SO3 were set: 3.0% in portland cements A1 and B1; 3.5% in portland cements A2 and B2; 4.0% in portland cements A3 and B3. At a given sulfate content in portland cement, the lower the clinker sulfate content, the more effective is the slump increase of the concrete caused by the superplasticizer addition. Moreover, the lower is the clinker sulfate content, the lower is the slump-loss rate of the superplasticized concrete mixture. Finally, at a given water-cement ratio, there is a reduction in the compressive strength at early ages (
{"title":"Influence of the Sulfate Level in the Clinker Phase on the Performance of Superplasticized Concretes","authors":"L. Coppola, R. Troli, P. Zaffaroni, M. Collepardi","doi":"10.14359/6044","DOIUrl":"https://doi.org/10.14359/6044","url":null,"abstract":"Portland cement contains sulfur compounds from the clinker phase and from added calcium sulfate (e.g., gypsum) which acts as a set regulator. The purpose of this investigation was to study the influence of the sulfate content in the clinker phase on the performance of superplasticized concrete mixtures in terms of initial slump level at a given water-cement ratio (0.45), slump-loss rate, and compressive strength at early and later ages. Two batches (A and B) of clinker from the same kiln source were studied, the main difference being the content of sulfate (SO3) in the clinker (0.72% and 1.40%, respectively). Different percentages of natural gypsum, as wet regulator, were interground in a laboratory mill to manufacture portland cements: A1, A2, A3 from clinker A, and B1, B2, B3 from clinker B. Three levels of total sulfate content in terms of SO3 were set: 3.0% in portland cements A1 and B1; 3.5% in portland cements A2 and B2; 4.0% in portland cements A3 and B3. At a given sulfate content in portland cement, the lower the clinker sulfate content, the more effective is the slump increase of the concrete caused by the superplasticizer addition. Moreover, the lower is the clinker sulfate content, the lower is the slump-loss rate of the superplasticized concrete mixture. Finally, at a given water-cement ratio, there is a reduction in the compressive strength at early ages (</= 3 days) when the low sulfate clinker is used to manufacture portland cements. These results are related to the effect of the clinker sulfate content on the degree of cement hydration: the lower the clinker sulfate content, the lower the early cement hydration in terms of gypsum consumption, ettringite formation, and tricalcium silicate (alite) hydration.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"520 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":"133631588","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 use of high strength normal weight and lightweight aggregate concrete (i.e., with water/binder ratios below 0.40) have shown that the concrete may be more sensitive to cracking the first hours and days after casting (due to autogenous shrinkage and thermal strains) than normal strength concretes. Two test rigs have been built in order to investigate the problem. The "Shrinkage-Rig" determines the "free" deformations (e.g., autogenous and thermal deformations), and the special "Stress-Rig" determines the stresses when the concrete is restrained against the deformations. The paper presents the results from testing of one high strength normal weight concrete and one high strength lightweight aggregate concrete, both with water/binder ratio 0.38, in the test rigs. Both concretes were exposed to two different temperature histories generated from heat of hydration. The normal weight concrete developed relatively high tensile strains during cooling phase. The corresponding stresses in the Stress-Rig became very high, and in one case the concrete failed. The lightweight aggregate concrete, however, did not develop any tensile strain, due to a lack of autogenous shrinkage caused by the water supply from the lightweight aggregate grains. Consequently, no severe tensile stresses were built up in the Stress-Rig.
{"title":"Cracking Tendency of High Strength Lightweight Aggregate Concrete at Early Ages","authors":"T. A. Hammer, Ø. Bjøntegaard, E. J. Sellevold","doi":"10.14359/6031","DOIUrl":"https://doi.org/10.14359/6031","url":null,"abstract":"The use of high strength normal weight and lightweight aggregate concrete (i.e., with water/binder ratios below 0.40) have shown that the concrete may be more sensitive to cracking the first hours and days after casting (due to autogenous shrinkage and thermal strains) than normal strength concretes. Two test rigs have been built in order to investigate the problem. The \"Shrinkage-Rig\" determines the \"free\" deformations (e.g., autogenous and thermal deformations), and the special \"Stress-Rig\" determines the stresses when the concrete is restrained against the deformations. The paper presents the results from testing of one high strength normal weight concrete and one high strength lightweight aggregate concrete, both with water/binder ratio 0.38, in the test rigs. Both concretes were exposed to two different temperature histories generated from heat of hydration. The normal weight concrete developed relatively high tensile strains during cooling phase. The corresponding stresses in the Stress-Rig became very high, and in one case the concrete failed. The lightweight aggregate concrete, however, did not develop any tensile strain, due to a lack of autogenous shrinkage caused by the water supply from the lightweight aggregate grains. Consequently, no severe tensile stresses were built up in the Stress-Rig.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"29 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":"114682215","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}
Transportation to and from Prince Edward Island, Canada's smallest province, has been by ferry for the past century. The cost to operate the ferry system became an increasing burden for the Canadian government and a proposal call was solicited in 1987 to the private sector to construct and operate an alternate system to the Province of Prince Edward Island. A proposal was accepted for a private consortium to build a 12.9 km bridge from the mainland to Prince Edward Island. The bridge was completed in May, 1997. A precast concrete, post-tensioned segmental box girder structure was selected for the site. A requirement of the Government of Canada was that the design and construction of the bridge provide a structure with a design life of 100 years. The bridge is located in a harsh marine environment, with some 100 annual cycles of freezing and thawing. Ice floes which originate in Northern waters pass through the Northumberland Strait in the winter and early spring months. Water temperatures vary from about -2 deg C in the winter months to +18 deg C in the summer. The salinity of the water in the Northumberland Strait is approximately 3.5%. This paper presents some of the durability concerns which were considered during the design and construction of the bridge and describes how these concerns were addressed. The discussion covers concrete materials and mixtures, air content and slump, chloride ingress, alkali-aggregate reactivity, sulphate attack, freezing and thawing resistance, ice abrasion, salt scaling, thermal cracking, and concrete curing.
在过去的一个世纪里，往返于加拿大最小省份爱德华王子岛的交通工具一直是渡轮。运营渡轮系统的成本成为加拿大政府日益沉重的负担。1987年，加拿大政府向私营部门征求建议，要求建造和运营一个替代爱德华王子岛省的渡轮系统。政府接受了一个私人财团的提议，建造一座从大陆到爱德华王子岛(Prince Edward Island)的12.9公里大桥。这座桥于1997年5月建成。现场选择了预制混凝土后张拉节段箱梁结构。加拿大政府的一项要求是，大桥的设计和建造提供了一个设计寿命为100年的结构。这座桥位于恶劣的海洋环境中，每年大约有100次冻融循环。在冬季和早春的几个月里，来自北方水域的浮冰穿过诺森伯兰海峡。水温从冬季的-2摄氏度到夏季的+18摄氏度不等。诺森伯兰海峡的海水盐度约为3.5%。本文介绍了在桥梁设计和建造过程中考虑到的一些耐久性问题，并描述了如何解决这些问题。讨论内容包括混凝土材料和混合物、空气含量和坍落度、氯化物侵入、碱骨料反应性、硫酸盐侵蚀、抗冻融性、冰磨损、盐结垢、热裂和混凝土养护。
{"title":"Some Durability Considerations in the Design of the Confederation Bridge","authors":"W. Langley, G. Forbes, E. Tromposch","doi":"10.14359/6028","DOIUrl":"https://doi.org/10.14359/6028","url":null,"abstract":"Transportation to and from Prince Edward Island, Canada's smallest province, has been by ferry for the past century. The cost to operate the ferry system became an increasing burden for the Canadian government and a proposal call was solicited in 1987 to the private sector to construct and operate an alternate system to the Province of Prince Edward Island. A proposal was accepted for a private consortium to build a 12.9 km bridge from the mainland to Prince Edward Island. The bridge was completed in May, 1997. A precast concrete, post-tensioned segmental box girder structure was selected for the site. A requirement of the Government of Canada was that the design and construction of the bridge provide a structure with a design life of 100 years. The bridge is located in a harsh marine environment, with some 100 annual cycles of freezing and thawing. Ice floes which originate in Northern waters pass through the Northumberland Strait in the winter and early spring months. Water temperatures vary from about -2 deg C in the winter months to +18 deg C in the summer. The salinity of the water in the Northumberland Strait is approximately 3.5%. This paper presents some of the durability concerns which were considered during the design and construction of the bridge and describes how these concerns were addressed. The discussion covers concrete materials and mixtures, air content and slump, chloride ingress, alkali-aggregate reactivity, sulphate attack, freezing and thawing resistance, ice abrasion, salt scaling, thermal cracking, and concrete curing.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"57 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":"130539120","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}
In this program, the performance of concrete masonry pavers is examined under freezing and thawing conditions of American Society for Testing and Materials (ASTM) C 1262-95. The 100 x 200 x 60 mm solid rectangular pavers of eight different mixture proportions were manufactured in a commercial plant and tested to determine their physical and inherent characteristics. Mass loss and surface condition under various freezing and thawing cycles, density, absorption, compressive strength, and tensile-splitting resistance were compared in order to assess the potential of each mixture proportion as a measure of field durability and quality control. The results obtained under ASTM C 1262 also enabled comparison with the degree of severity experienced by the same group of pavers under the other ASTM and Canadian freezing and thawing (with or without deicing salt) tests.
在这个程序中，混凝土砌体摊铺机的性能在美国材料试验协会(ASTM) C 1262-95的冻结和解冻条件下进行了检查。100 x 200 x 60 mm的实心矩形铺路石由八种不同的混合比例在一家商业工厂生产，并测试了它们的物理和固有特性。通过比较不同冻融循环下的质量损失和表面状况、密度、吸收量、抗压强度和抗拉劈裂性，以评估每种混合比例作为现场耐久性和质量控制指标的潜力。在ASTM C 1262下获得的结果也可以与在其他ASTM和加拿大冻融(有或不除冰盐)试验下同一组摊铺机所经历的严重程度进行比较。
{"title":"Performance of Solid Concrete Pavers Under Freeze-Thaw and Deicing Salt Environments of Newly Adopted ASTM C 1262 Test Method","authors":"N. Ghafoori, S. Kassel","doi":"10.14359/6073","DOIUrl":"https://doi.org/10.14359/6073","url":null,"abstract":"In this program, the performance of concrete masonry pavers is examined under freezing and thawing conditions of American Society for Testing and Materials (ASTM) C 1262-95. The 100 x 200 x 60 mm solid rectangular pavers of eight different mixture proportions were manufactured in a commercial plant and tested to determine their physical and inherent characteristics. Mass loss and surface condition under various freezing and thawing cycles, density, absorption, compressive strength, and tensile-splitting resistance were compared in order to assess the potential of each mixture proportion as a measure of field durability and quality control. The results obtained under ASTM C 1262 also enabled comparison with the degree of severity experienced by the same group of pavers under the other ASTM and Canadian freezing and thawing (with or without deicing salt) tests.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"146 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":"124693445","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 the results of an investigation about the behavior of reinforced concrete flat slabs made with high strength concrete, steel fibers and ordinary shear reinforcement. We tested twelve flat slabs made with different combinations of high strength concrete, ordinary strength concrete, shear reinforcement and steel fiber volume fraction (0%, 0.75% and 1.5%). The square-shaped slabs were designed to represent the slab-column connection in an interior column. A significant increase in the punching shear strength was observed, due to the use of high strength concrete and the addition of steel fibers. The combination of high strength concrete with 1.5% fiber volume fraction and shear reinforcement provided twice the punching shear resistance of an ordinary strength concrete slab without shear reinforcement and without fibers. Fiber addition is believed to be responsible for an increase of approximately 50% in the resistance and also for an increase in ductility. Comparisons with theoretical code provisions, including CEB/90, ACI-318/89 and Eurocode 2, are presented.
{"title":"Punching Shear Resistance of High Strength Concrete Flat Slabs Reinforced with Steel Fibers and Transverse Reinforcement","authors":"J. B. Hanai, Enz Vargas","doi":"10.14359/6054","DOIUrl":"https://doi.org/10.14359/6054","url":null,"abstract":"The paper presents the results of an investigation about the behavior of reinforced concrete flat slabs made with high strength concrete, steel fibers and ordinary shear reinforcement. We tested twelve flat slabs made with different combinations of high strength concrete, ordinary strength concrete, shear reinforcement and steel fiber volume fraction (0%, 0.75% and 1.5%). The square-shaped slabs were designed to represent the slab-column connection in an interior column. A significant increase in the punching shear strength was observed, due to the use of high strength concrete and the addition of steel fibers. The combination of high strength concrete with 1.5% fiber volume fraction and shear reinforcement provided twice the punching shear resistance of an ordinary strength concrete slab without shear reinforcement and without fibers. Fiber addition is believed to be responsible for an increase of approximately 50% in the resistance and also for an increase in ductility. Comparisons with theoretical code provisions, including CEB/90, ACI-318/89 and Eurocode 2, are presented.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"445 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125846588","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. Ueda, A. Hattori, T. Miyagawa, M. Fujii, S. Mizoguchi, M. Ashida
Desalination is the electrochemical method aiming to remove chlorides from reinforced concrete structures. Until now, it has been applied only to reinforced concrete structures and not to prestressed concrete structures. In this study, desalination was applied to chloride contaminated concrete specimens with pretensioned prestressing steel bars. As a result of the slow strain rate tensile test of prestressing bars after applying desalination, significant influence of treatment on the elastic behavior and plastic behavior until the tensile strength point was not shown but the influence of hydrogen embrittlement due to treatment was impacted on the fracture strength and the contraction rate of fractured sections. As a result of absorbed hydrogen measurement of prestressing steel bars from treated specimens, the release peak of diffusible hydrogen was found. Furthermore, as a result of keeping treated specimens for 1 month, the first peak of diffusible hydrogen (around 470 K) and the change of the fracture behavior due to hydrogen embrittlement disappeared.
{"title":"Influence of Desalination on Behavior of Prestressing Steel","authors":"T. Ueda, A. Hattori, T. Miyagawa, M. Fujii, S. Mizoguchi, M. Ashida","doi":"10.14359/6045","DOIUrl":"https://doi.org/10.14359/6045","url":null,"abstract":"Desalination is the electrochemical method aiming to remove chlorides from reinforced concrete structures. Until now, it has been applied only to reinforced concrete structures and not to prestressed concrete structures. In this study, desalination was applied to chloride contaminated concrete specimens with pretensioned prestressing steel bars. As a result of the slow strain rate tensile test of prestressing bars after applying desalination, significant influence of treatment on the elastic behavior and plastic behavior until the tensile strength point was not shown but the influence of hydrogen embrittlement due to treatment was impacted on the fracture strength and the contraction rate of fractured sections. As a result of absorbed hydrogen measurement of prestressing steel bars from treated specimens, the release peak of diffusible hydrogen was found. Furthermore, as a result of keeping treated specimens for 1 month, the first peak of diffusible hydrogen (around 470 K) and the change of the fracture behavior due to hydrogen embrittlement disappeared.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115014845","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 report documents a survey conducted for the purpose of evaluating the concrete protection effects of chloride attack measures applied to a new prestressed concrete bridge located in a chloride attack environment. The chloride attack measures which consisted of (1) applying a concrete protection lining, and (2) installing waterproofing panels, were performed on different girders of the same bridge, respectively. Then, roughly twelve years after the time of construction, the protection effects of each method were evaluated based on appearance, chloride content and chipping surveys. Both methods were found to have sufficient barrier effects against the ingress of corrosive factors into the concrete from the outside.
{"title":"Effects of Protective Methods Against Salt Damage for New Prestressed Concrete Bridge","authors":"Y. Takizawa","doi":"10.14359/6046","DOIUrl":"https://doi.org/10.14359/6046","url":null,"abstract":"This report documents a survey conducted for the purpose of evaluating the concrete protection effects of chloride attack measures applied to a new prestressed concrete bridge located in a chloride attack environment. The chloride attack measures which consisted of (1) applying a concrete protection lining, and (2) installing waterproofing panels, were performed on different girders of the same bridge, respectively. Then, roughly twelve years after the time of construction, the protection effects of each method were evaluated based on appearance, chloride content and chipping surveys. Both methods were found to have sufficient barrier effects against the ingress of corrosive factors into the concrete from the outside.","PeriodicalId":255305,"journal":{"name":"SP-179: Fourth CANMET/ACI/JCI Conference: Advances in Concrete Technology","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121341290","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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