2000 Fiscal Year Final Research Report Summary
Role of Fine Mineral Powders to Produce High-Performance Concrete
| Project/Area Number |
11650469
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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 |
土木材料・力学一般
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| Research Institution | Hachinohe Institute of Technology |
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Principal Investigator |
SHOYA Masami Hachinohe Institute of Technology, Civil Engineering, Professor, 工学部, 教授 (80006684)
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| Co-Investigator(Kenkyū-buntansha) |
ABA Minoru Hachinohe Institute of Technology, Civil Engineering, Assistant Professor, 工学部, 講師 (10295959)
TSUKINAGA Yoichi Hachinohe Institute of Technology, Architectural Engineering, Professor, 工学部, 教授 (60124898)
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| Project Period (FY) |
1999 – 2000
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| Keywords | High-performance concretes / Fine mineral powder / Bleeding / Water retentivity / Water retaining factor / Character of powder particle / Interfacial zone / High durable concrete |
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| Research Abstract |
In recent years, it has been pointed out that concrete structures are likely suffer the attacks due to excess load and aggravated environment, and various function and performance for them are required. Given this background, High-performance concrete with high strength, high durability and self-compacting has been developed. Fine mineral powder is considered to play an important key factor to produce these high-performance concretes. The purpose of this study is to investigate the role of water retentivity of fine mineral powder to make the concrete with high quality such as high durability. Test results are summarized as follows ;
1. Characters of fine mineral powders, such as specific surface area by BET, particle size distribution, shape factor and percentage of void, are evaluated.
2. The capability to retain water by the fine mineral powders is examined to estimate water retaining factors which were definea from flow test, bleeding test and centrifugation test using powder paste. M
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utual relationships are investigated not only among the water retaining factors but also between these factors and physical properties of the powders.
3. The effect for improving amount and rate of concrete bleeding is studied using nine fine mineral powders which are replaced some the volume of sand. The effect to reduce the bleeding of concrete by the powder is closely related to its capability to retain water. Effect of fine mineral powder incorporated on reduction of concrete bleeding could be estimated by water retaining factor defined in these powder paste tests.
4. Water with air voids in fleshly placed concrete will be moved toward the surface. When the bleeding is excessive, harmful effects will arise on production of defects such as the formation of water channels and water pockets beneath the coarse aggregates, and the spacing factor was increased near the surface layer of concrete.
5. The bleeding of concrete broadly influences interfacial zone of coarse aggregates in concrete. Especially, at the 20mm〜40mm from placed side of concrete, the weakness zone around coarse aggregates is increased. The weakness zone will result in less frost resistance of concrete.
6. The application of mineral fine powders is very effective to make proper air-void system, to form the fine pore structures and to control the weakness zone around coarse aggregates, and it was very important for make the high durable concrete. Less
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