1988 Fiscal Year Final Research Report Summary
Influence of Superretarding Admixtures on the Properties of Cement and Concrete.
| Project/Area Number |
61550420
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Building structures/materials
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| Research Institution | Fukuoka University |
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Principal Investigator |
SHIIBA Hiroyuki Professor of Technical Architecture, University of Fukuoka, 工学部建築学科, 教授 (30103782)
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| Co-Investigator(Kenkyū-buntansha) |
HONDA Satoru Assistant of Technical Architecture, University of Fukuoka, 工学部建築学科, 助手 (70181550)
YAMATO Takesi Professor of Civil Engineering, University of Fukuoka, 工学部土木工学科, 教授 (90078650)
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| Project Period (FY) |
1986 – 1988
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| Keywords | Superretarding Admixture / Set-Retarded Concrete / Construction Joint / Time of Setting / Curing Temperature / Workability / Penetration Resistance / 水平量 |
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| Research Abstract |
In these days, it has become necessary to ensure a monolithic structure of concrete. Therefore the avoidance of cold joints is essential and superretarding admixtures prolong the setting time for which concrete can be vibrated.
A conciderable amount of research has been carried out to elucidate the mechanism by which superretarding admixtures delay the setting time of cement concrete. It has been suggested that adsorption of organic compounds on the surface of the cement compounds prevent reaction with water.
However, it has been shown that superretarding admixtures are not strongly adsorbed on the cement hydration products. Because the adsorption by the C_3S (which contributes to the concrete's early strength) is low, it is considered that an adsorption mechanism is not the primary cause of retardation.
This paper describes the results of fundamental studies on the physical effects of superretarder added cement and concrete. Therefore the extent of the knowledge has been obtained for early compressive strength, young's modulus and workability according to setting time by penetraction resistance methods, and for the construction joints of concrete in which splitting tensile strengths and flexural strengths of horizontal and vertical construction joints between new and old concrete under the various conditions.
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