2006 Fiscal Year Final Research Report Summary
Development of Expansive-High Strength Concrete and Systematic Evaluation of Structural Behavior of Reinforced Concrete Beams
| Project/Area Number |
16360220
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Civil engineering materials/Construction/Construction management
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| Research Institution | Hiroshima University |
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Principal Investigator |
SATO Ryoichi Hiroshima University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (20016702)
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| Co-Investigator(Kenkyū-buntansha) |
HOSODA Akiro Yokohama National University, Faculty of Environment and Science, Associate Professor, 大学院工学研究院, 助教授 (50374153)
KONDO Kazuo Graduate School of Engineering, Associate Professor, 大学院工学研究科, 助教授 (00116584)
KAWAI Kenji Graduate School of Engineering, Associate Professor, 大学院工学研究科, 助教授 (90224716)
MARUYAMA Ippei Nagoya University, Graduate School of Environmental Studies, Associate Professor, 大学院環境学研究科, 助教授 (40363030)
ITO Hidetoshi Hiroshima Institute of Technology, Faculty of Engneering, Associate Professor, 工学部, 助教授 (90104067)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Expansive-high strength concrete / Autogenous shrinkage / Reinforced concrete / Flexural crack width / Micro cracking / Curvature / Shear strength |
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| Research Abstract |
Expansive-high strength concrete(E-LAS) with compressive strength over 100N/mm^2 and expansive strain reaching 200 X 10^<-8> at maximum was developed, which was made of low heat Portland cement, expansive additive and shrinkage reducing agent.Stress produced in E-LAS ranged from 0.5 to・.2 N/mm2, which was not strongly dependent on the strain.
The ultimate and rate of creep strains of E-LAS and conventional HSC(N-HAS) obtained experimentally showed less difference between both concretes for the case of with water to binder ratios(W/B) of 0.3. Linear creep analysis based on step by step for reinforced HSC beams showed fairly good agreement with experimental results, while the former overestimated shrinkage stress and underestimate expansive stress of HSC with W/B of 0.15 with the increase of RB ratio. The reason for the overestimate of shrinkage stress was explained by the detection of micro cracking developed in the radial direction and the computed result was improved by incorporating t
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ension softening of concrete depending on the age.
Effectiveness of E-LAS was verified by experiment for improving the serviceability performance of short-and long-term flexural crack width as well as curvature of reinforced concrete(RC) beams and a new concept was proposed for evaluating them based on the strain change in tension RB from the zero concrete stress condition at tension RB depth to the loaded condition and the change of stress related curvature before and after loading, respectively, whose validity was verified by comparing with results obtained by conventional method and experiment, while tension softening effect must be considered in case of small crack width.
Shear strength at diagonal cracking of E-LAS beams, whose effective depth(d) is from 250-1000mm and strain in tension RB before loading is almost zero, was improved by 5% for d=250mm, 12% for d=500mm and 19% for d=1000mm, compared with that of N-HAS beams with remarkable shrinkage strain in the same RB. A concept of equivalent tension RB ratio considering RB strain due to early age deformation was proposed. The concept showed the linear relationship between shear strength at diagonal cracking and (effective depth)^<-1/3> independent of early age deformation, while previouisly proposed equations followed the law of (effective depth)^<-1/2> and (effective depth)^<-2/5> for RC beams made of N-HAS. A proposed equation formulated based on this concept showed high prediction accuracy independent of the magnitude of early age deformation in concrete.
E-LAS was also effective in improving shear strength of RC beams which was 13% for shear RB ratio of 0.25% and 6% for 0.51% higher than that of corresponding N-HAS beam, respectively. The shear RB strains averaged along a primary shear crack of E-LAS beams were smaller than those of N-HAS beams which could be roughly predicted by the modified truss theory applied a proposed equation for evaluating concrete contribution for shear resistance. Less
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Research Products
(68 results)
