超低水胶比及硅灰对水泥净浆早期自收缩的影响-《混凝土与水泥制品》杂志社

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超低水胶比及硅灰对水泥净浆早期自收缩的影响

Influence of Very Low W/B and Silica Fume on Early Autogenous Shrinkage of Cement Paste

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关键词：

超低水胶比；硅灰；自收缩；毛细负压；水化程度

Key words：

Very low W/B; Silica fume; Autogenous shrinkage; Capillary pressure; Hydration degree

刊期：

２０16年第4期

DOI：

文章编号：

1000-4637（2016）04-01-04

基金项目：

国家自然科学基金项目（51438003）

作者：

葛晓丽1，刘加平1,2,3，王育江3，田倩3，杨斌3

单位：

1.重庆大学材料科学与工程学院，400045；2. 东南大学材料科学与工程学院，南京 210096； 3.江苏省建筑科学研究院有限公司高性能土木工程材料国家重点实验室，南京210008

摘要

摘要：采用自行研制的波纹管测试系统，测试超低水胶比水泥净浆的早期自收缩；并通过测试毛细管负压和水化程度，对自收缩结果进行分析，定性阐述超低水胶比水泥净浆的自收缩机理及规律。结果表明，当水胶比低于0.18时，水泥净浆的自收缩随水胶比的减小而降低；反之则增加；当水胶比为0.18（临界水胶比）时，水泥净浆的自收缩最大。硅灰可以很好地抑制超低水胶比水泥净浆的自收缩，当水胶比为0.15，硅灰掺量为5%和10%时，水泥基材料48h的自收缩分别降低了25.8%和56.3%。

Abstract: Early autogenous shrinkage of cement paste with very low W/B was measured with self-designed corrugated tubes. According to the capillary pressure and hydration progress, the early autogenous shrinkage was analyzed. Meanwhile, mechanism of early autogenous shrinkage was qualitatively presented. The results show that the autogenous shrinkage of cement paste decreases with the reducing of W/B in the case of W/B≤0.18, while a contrary tendency is presented when W/B is over 0.18; a critical W/B of 0.18 is observed in which autogenous shrinkage of cement paste would reach maximum. Silica fume is effective to restrain the early autogenous shrinkage of cement paste with very low W/B. When the W/B is 0.15 and the contents of silica fume are 5% and 10%, the autogenous shrinkage would decrease by 25.8% and 56.3% after 48h.

结论

（1）水胶比对超低水胶比水泥净浆早期自收缩的影响存在临界值，临界水胶比为0.18。大于临界水胶比时，水泥净浆的自收缩随水胶比的增大而降低；小于临界水胶比时，水泥净浆的自收缩随水胶比的降低而降低；等于临界水胶比时，水泥净浆自收缩最大，其48h的自收缩可高达3248μm/m。

（2）硅灰可有效抑制水胶比为0.15的水泥净浆的早期自收缩，且掺量越高抑制作用越大，5%和10%的硅灰可使48h自收缩分别降低25.8%和56.3%。

（3）在水泥净浆水化初期，水胶比主要通过影响水化程度和早期毛细负压来影响自收缩。硅灰对超低水胶比水泥净浆早期自收缩的影响机理尚不十分明确，真正的原因还有待进一步研究。

参考文献

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