西安建筑科技大学学报(自然科学版)

通过试验研究了不同含气量对路面常用C35混凝土流动性、抗压强度、早期收缩、后期收缩的影响并通过图像处理的手段分析孔隙率和分级孔隙率对90 d收缩的影响.结果表明:混凝土的流动性随着含气量的升高先增大后减小,含气量为6.5%时坍落度达到最大值165 mm.抗压强度随含气量的升高而降低.混凝土的含气量越高对早期收缩变形的抑制越明显,当含气量为8.0%时72 h收缩率最小; 7 d以前混凝土的收缩率随着混凝土含气量的升高而减小; 14～90 d混凝土收缩率随着含气量的升高而增大.含气量为4.6%时混凝土的流动性、抗压强度和收缩性能得到较好的平衡.图像法分析可知孔隙率越大90 d混凝土收缩率越大,其中孔径为1 000～2 000 μm的气孔对90 d收缩贡献最大而10～100 μm的气孔对90 d收缩贡献最小.该方法简便快捷为今后工程应用提供了很好的理论依据.

In this paper, the effects of different air content on the fluidity, compressive strength, early shrinkage and late shrinkage of C35 concrete are studied experimentally, and the effects of porosity and graded porosity on 90 day shrinkage are analyzed by means of image processing. The results show that the fluidity of concrete increases first and then decreases with the increase of air content, and the maximum slump is 160 mm when air content is 6.5%, and the compressive strength decreases with the increase of air content. The higher the air content of concrete, the more obvious the restraint of early shrinkage deformation. When the air content is 8.0%, the shrinkage rate of 72 hours is the smallest; before 7 days, the shrinkage rate of concrete decreases with the increase of air content of concrete; and after 14 days to 90 days, the shrinkage rate of concrete increases with the increase of air content. When the air content is 4.6%, the fluidity, strength and shrinkage of concrete can be well balanced. The image analysis shows that the larger the porosity is, the larger the shrinkage of concrete in 90 days. The pore size of 1 000～2 000 μm contributes the most to the shrinkage in 90 days, while the pore size of 10～100 μm contributes the least to the shrinkage in 90 days. This method is simple and fast, which provides a good theoretical basis for future engineering applications.

引言
1 试验原材料及试验方法
2 试验结果与分析
3 结论

图1 K12引气剂摇泡状态<br/>Fig.1 Shaking state of air entraining agent K12

图1 K12引气剂摇泡状态
Fig.1 Shaking state of air entraining agent K12

表1 混凝土配合比/(kgm-3)<br/>Tab.1 Concrete mix ratio/(kgm-3)

表1 混凝土配合比/(kgm-3)
Tab.1 Concrete mix ratio/(kgm-3)

表2 不同含气量时混凝土的性能<br/>Tab.2 Performance of concrete with different air content

表2 不同含气量时混凝土的性能
Tab.2 Performance of concrete with different air content

图2 不同含气量时混凝土的早期收缩<br/>Fig.2 Early shrinkage of concrete with different air content

图2 不同含气量时混凝土的早期收缩
Fig.2 Early shrinkage of concrete with different air content

图3 不同含气量时混凝土的后期收缩<br/>Fig.3 Later shrinkage of concrete with different air content

图3 不同含气量时混凝土的后期收缩
Fig.3 Later shrinkage of concrete with different air content

表3 不同含气量时90 d混凝土的孔径分布<br/>Tab.3 Pore size distribution of 90 d concrete with different air content

表3 不同含气量时90 d混凝土的孔径分布
Tab.3 Pore size distribution of 90 d concrete with different air content

图4 90 d混凝土的气孔分布和形貌特征<br/>Fig.4 Pore distribution and morphological characteristics of 90 d concrete

图4 90 d混凝土的气孔分布和形貌特征
Fig.4 Pore distribution and morphological characteristics of 90 d concrete

图5 不同含气量时孔隙率对90 d混凝土收缩的影响<br/>Fig.5 Effect of porosity on shrinkage of 90 d concrete with different air content

图5 不同含气量时孔隙率对90 d混凝土收缩的影响
Fig.5 Effect of porosity on shrinkage of 90 d concrete with different air content

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备注

引言

1 试验原材料及试验方法

2 试验结果与分析

3 结论

期刊信息