碳酸盐岩质机制砂石制备高性能自密实混凝土微孔隙结构试验研究

Experimental study on micropore structure of high performance self-compacting concreteprepared by carbonate sand

为了探究高性能自密实混凝土(C80)微孔结构分布特征,采用高分辨率X射线计算机断层扫描试验、AVIZO软件、扫描电镜等方法对碳酸盐质机制砂石自密实混凝土试件内部孔隙结构进行观测分析,主要结论如下:在碳酸盐岩质高性能自密实混凝土内部存在大量的孔隙结构,在10μm的测试精度范围内,微孔呈现圆形特征,整体圆整度较好。通过SEM扫描电镜观测可知,在高性能混凝土内部存在着微裂隙或贯通的裂隙结构,这些裂隙的宽度在0.5~2μm,样品的内部存在3~10μm的微小空洞。碳酸盐岩质机制砂自密实混凝土内部的微孔洞进行统计分析,孔洞直径服从三参数正态分布,受试验观测及精度的限制,试验统计结果呈现正偏(高峰偏左)现象,故提出一种“纠正偏峰”方法对统计结果“第三参数C”的计算进行的分析和探讨,结果表明所提出的方法可以快速、客观、较优地确定第三参数,弥补10μm以下未统计到的缺失数据及试验样品有限的限制,为检验混凝土内孔洞的分布提供了参考。

In order to explore the micropore structure distribution characteristics of high performance self-compacting concrete(C80),high-resolution X-ray computed tomography test,AVIZO software,scanning electron microscopy and other methods were used to observe and analyze the internal pore structure of carbonate mechanism sand and gravel self-compacting concrete specimens.The main conclusions are as follows,there are a lot of pore structures in the carbonate high-performance self-compacting concrete.The pores show circular characteristics and the overall roundness is good within the test accuracy range of 10μm.By SEM scanning electron microscope observation,it can be seen that there are micro cracks or through cracks in the high performance concrete.The width of these cracks is about from 0.5μm to 2μm,and there are from 3μm to 10μm tiny voids in the sample.Statistical analysis ofmicro-pores in carbonate sand self-compacting concrete shows that the diameter of pores follows the normal distribution of three parameters.Limited by experimental observation and accuracy,the statistical results show a positive bias(peak deviation to the left)phenomenon.A method of"correcting peak deviation"is proposed to analyze and discuss the calculation ofthe"third parameter C"of the statistical results.The results show that the method proposed can determine the third parameter quickly,objectively and optimally,and make up for the limitations of missing data less than 10μm and limited test samples,which provides a reference for inspecting the distribution of holes in concrete.