再生混凝土抗折强度尺寸效应研究

Study on Size Effect of Flexural Strength of Recycled Concrete

为促进再生混凝土在土建工程中的进一步应用,本文制作了0,25%,50%,79%和100%的5种不同再生骨料取代率的试件、以全取代率再生混凝土为基底添加0.25%,0.5%,0.75%和1.0%体积掺量钢纤维的再生混凝土试件及强度等级分别为C20,C30和C40的3种全取代率再生混凝土试件,探究不同取代率、不同钢纤维掺量及不同强度等级对再生混凝土抗折强度尺寸效应的影响。实验结果表明,由于再生骨料自身的缺陷,各取代率下再生混凝土抗折强度均小于普通混凝土;掺加钢纤维后,钢纤维可以减少内部初始裂纹和试件受荷后裂纹的发展,由此提升了其抗折强度指标;当混凝土的强度等级不同时,相同背景下混凝土的抗折强度尺度效应也不相同,随着等级越高,效应会变得更加显著。

In order to promote the further application of recycled concrete in civil engineering,this paper has made five specimens with different recycled aggregate substitution rates of 0,25%,50%,79% and 100%,recycled concrete with full replacement rate recycled concrete as the base and added 0.25%,0.5%,0.75% and 1.0% volume content of steel fibers and strength grades three kinds of recycled concrete specimens with full substitution rates of C20,C30 and C40 were used to explore the effects of different substitution rates,different steel fiber contents and different strength grades on the size effect of the flexural strength of recycled concrete.The experimental results show that due to the defects of the recycled aggregate itself,the flexural strength of recycled concrete is lower than that of ordinary concrete at each substitution rate,and after adding steel fibers,steel fibers can reduce the development of internal initial cracks and cracks after the specimen is loaded,this improves its flexural strength index,and when the strength levels of concrete are different,the flexural strength scale effect of concrete under the same background is also different,and the effect becomes more significant with the higher the level.