Effects of Silica Fume and Shrinkage Reducing Admixture on Autogenous Shrinkage and Porosity of Concrete

Abstract

Abstract: Silica fume and low water-binder ratio will reduce the total porosity of concrete, but increase the autogenous shrinkage of concrete and lead to microcracks. In this paper, the effects of silica fume and shrinkage reducing admixture (SRA) on autogenous shrinkage and pore size distribution in micro and macro scale of concrete with different water-binder ratios were studied. The results show that the autogenous shrinkage of concrete increases by 27.3%~28.8% with the addition of 10% (volume fraction) of silica fume, while the autogenous shrinkage of concrete decreases by 68.0%~85.1% with the addition of SRA, and even more to the concrete samples containing silica fume. In addition, the addition of silica fume and SRA reduces the total porosity of concrete by 5.1%~6.0% and 35.9%~39.7%, respectively, but silica fume increases the proportion of pore volume below 100 nm and above 100 μm, while SRA has the opposite effect on the volume of these two types of pores. At the same time, there is a significant positive correlation between autogenous shrinkage and pore volume fraction above 100 μm.

Key words: silica fume, shrinkage reducing admixture, water-binder ratio, autogenous shrinkage, pore size distribution, porosity

CLC Number:

TU528.01

HUANG Zhengfeng, OU Zhongwen, LUO Wei, WANG Fei, WANG Tingfu. Effects of Silica Fume and Shrinkage Reducing Admixture on Autogenous Shrinkage and Porosity of Concrete[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2022, 41(9): 3077-3083.

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