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A STUDY ON NEW MIXING METHOD AIMED AT MAKING TO QUALITY OF HIGH STRENGTH LOW WATER-CEMENT RATIO CONCRETE

提高高强低水灰比混凝土质量的新拌和方法研究

基本信息

批准号：
16560400
负责人：
KASAI Tetsurou
金额：
$ 1.66万
依托单位：
TOKAI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560400/
关键词：
Hydrate of cement Low water-cement ratio Hydration reaction Chemical shrinkage Self-desiccation Autogenerous shrinkage Curing of concrete Water penetration 高強度コンクリート

项目摘要

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

研究了养护水渗透条件对胶凝材料性能的影响。在水灰比较低的大尺寸试件中，标准水养护时的混合水和渗透水均不足以完成整个试件的水化。因此，养护条件进行了研究，以提高性能的试样在任何距离的表面在水化过程中。当水灰比较低时，采用低表面张力的AE掺合料水化养护和高压水养护，比常规水养护能更好地提高水化程度和强度，在水化过程中补充水对胶凝材料的性能有较大影响。研究结果表明：1）对于水灰比较低的硬化水泥浆体，如水灰比为0.20，0.2 ...更多信息 5和0.30时，发现混合水不能填充由于水化反应而形成的孔隙，并且不能渗透到硬化水泥浆体的中心部分。在水灰比较低的试样中，从试样表面到试样中部的任意距离处，均表现出不同程度的水化和水化不足引起的自干燥现象。3）低水灰比高强混凝土经标准水养护后，其水化和自干燥程度在表层和本体存在明显差异。因此，由于表面张力的差异，不适合采用与普通混凝土相同的养护条件。不同的养护水对试样的渗透程度和自干燥程度有不同的影响。需要进一步研究，以找到合适的养护条件作为高强度混凝土的标准。然而，在本文中，发现高压水养护和低表面张力水养护能够发展的强度比与标准养护，特别是在低水灰比的标本。少