高石粉含量机制砂混凝土匀质性的试验研究  

Experimental Study on Homogeneity of Machine-made Sand Concrete with High Stone Powder Content

作　　者：刘龙龙 赵尚传[1] 刘忠凯 王少鹏 刘荣欣 LIU Long-long;ZHAO Shang-chuan;LIU Zhong-kai;WANG Shao-peng;LIU Rong-xin(Research Institute of Highway,Ministry of Transport,Beijing 100088,China;China Overseas Construction Co.,Ltd.,Shenzhen Guangdong 518057,China)

机构地区：[1]交通运输部公路科学研究院,北京100088 [2]中海建筑有限公司,广东深圳518057

出　　处：《公路交通科技》2022年第8期127-133,141,共8页Journal of Highway and Transportation Research and Development

摘　　要：为保障机制砂混凝土的耐久性,解决高石粉含量机制砂混凝土匀质性差、易开裂的问题,按照强度等级C50,C40,C30,水胶比分别为0.31,0.36,0.45,制备了尺寸150 mm×150 mm×150 mm机制砂混凝土试件,其中3组采用最大密实度理论分配粗、细骨料比例,另外3组采用原配合比设计。将浇注的试件标准养护28 d后再进行机械切割成混凝土切片。然后用MATLAB软件对试件切片二值化处理,并将二值化后的切片照片进行3×3等分处理。最后利用Image-Pro Plus软件读取二值化处理的切片中骨料颗粒数量和面积,依据现有的匀质性评估模型,对比分析了不同配合比设计中机制砂级配、石粉含量、骨料最大粒径及水胶比等因素对机制砂混凝土匀质性的影响。试验结果表明:机制砂石粉含量较高时,水胶比相同,采用最大密实度理论分配粗、细骨料可减少机制砂比例,增加粗骨料含量,提升其匀质性;减小水胶比,提升混凝土强度等级时,试件切片中骨料的面积减少、浆体面积增加,有助于提高混凝土的匀质性;对比不同配合比设计方法中骨料最大粒径、水胶比、骨料级配等因素对混凝土匀质性的影响程度,骨料的最大粒径对机制砂混凝土的匀质性影响最大;采用最大密实度理论分配机制砂粗、细骨料比例可以有效缓解机制砂石粉含量高导致的机制砂混凝土匀质性差的问题,验证了其用于机制砂混凝土配合比设计的可行性。To guarantee the durability of machine-made sand concrete and solve the problems of poor homogeneity and easy cracking of high stone powder content machine-made sand concrete,according to the strength grades of C50,C40,C30 and the water-binder ratios of 0.31,0.36,0.45,the machine-made sand concrete specimens with dimensions of 150 mm×150 mm×150 mm are prepared.Among them,3 groups of specimens are assigned the ratio of coarse and fine aggregates according to the maximum density theory,and the other 3 groups of specimens are designed by using original mix ratio.After 28 days of standard curing,these specimens are mechanically cut into concrete slices.Then,the specimen slices are binarized with MATLAB software,and the binarized slice photos are divided into 3×3 equal parts.Finally,the number and area of aggregate particles in the binarized slices are read by using the Image-Pro Plus software.According to the existing homogeneity evaluation model,the influences of gradation,stone powder content,maximum aggregate particle size and water-binder ratio of machine-made sand concrete with different mix ratio designs on the homogeneity of machine-made sand concrete are analyzed.The test result shows that(1) when the content of machine-made sand powder is high and the water-binder ratio is the same,distributing coarse and fine aggregates by the maximum density theory can reduce the proportion of machine-made sand,increase the content of coarse aggregate and improve the homogeneity;(2) comparing the influence degrees of the maximum aggregate particle size,water-binder ratio and aggregate gradation on the homogeneity of concrete in different mix design methods,the maximum aggregate particle size of has the greatest influence on the homogeneity of the machine-made sand concrete(3) using the maximum density theory to distribute the proportion of coarse and fine aggregates of machine-made sand powder can effectively alleviate the poor homogeneity of machine-made sand concrete caused by the high content of machine-made sand pow

关 键 词：桥梁工程 机制砂混凝土 匀质性评估模型 石粉含量 匀质性 

分 类 号：TU528.041[建筑科学—建筑技术科学]