2005 Fiscal Year Final Research Report Summary
A STUDY ON NEW MIXING METHOD AIMED AT MAKING TO QUALITY OF HIGH STRENGTH LOW WATER-CEMENT RATIO CONCRETE
| Project/Area Number |
16560400
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | TOKAI UNIVERSITY |
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Principal Investigator |
KASAI Tetsurou TOKAI UNIVERSITY, School of Engineering, Professor, 工学部, 教授 (20266373)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Hydrate of cement / Low water-cement ratio / Hydration reaction / Chemical shrinkage / Self-desiccation / Autogenerous shrinkage / Curing of concrete / Water penetration |
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| Research Abstract |
Influences of penetrative condition of curing water on properties of cementitious materials were investigated. In a large-size specimen with a low water-cement ratio (W/C), both the mixing water and penetrative water at standard water curing are not sufficient to complete the hydration of the entire specimen. Therefore, curing conditions were studied to improve the properties of the specimens at any distances from the surface during hydration process. When W/C is low, specimens cured with water containing AE-admixture, which has low surface tension, and water under high pressure was able to improve the degree of hydration and strength more than those subjected to the standard water curing.
Curing of supplying additional water to a specimen during hydration has large influences on properties of cementations materials. The following conclusions regarding to influences of penetrative curing were obtained in this study :
1) For the hardened cement pastes with low W/C, such as W/C of 0.20,0.2
… More
5 and 0.30, it was found that the mixing water was unable to fill pores formed as a result of hydration reaction, and to penetrate into the central part of hardened cement pastes. A larger self-desiccation occurs in the middle part of specimens and the progress of hydration became slower.
2) At any distance from surface to middle part of the specimen with a low W/C, different degree of hydration and self desiccation due to the lack of hydration were shown. Additionally, the strength in the central part of specimens was lower than in the near-surface-area specimens.
3) The high-strength concrete with low W/C that treated by the standard water curing clearly showed difference in degree of hydration and self-desiccation in the bulk and in the surface layer. Consequently, it is not suitable to apply the same curing condition as applied to the normal concrete because of the difference in surface tension. The degree of the penetration of water into the specimen and degree of self-desiccation were different by the curing water. Further investigations to find the appropriate curing condition as standard for the high-strength concrete, are needed. Nevertheless in this paper, it was found that high pressure water curing and low surface tension water curing was able to develop strength of specimens more than that with the standard curing, especially at a low W/C ratio. Less
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Research Products
(6 results)
