不同砂率条件下再生混凝土的强度及收缩变化规律

Change Rules of Strength and Shrinkage for Recycled Concrete under Different Sand Ratio

为研究不同砂率条件下再生混凝土的抗压强度及干燥收缩性能变化规律,以再生粗骨料取代率为100%、强度等级为C30的再生混凝土为例,分别对不同砂率条件下的再生混凝土进行了含气量、稠度、抗压强度以及干燥收缩等试验,同时将其对比于普通混凝土试件,得出结论:同配比条件下,C30强度再生混凝土的含气量随着砂率的增大而增大,坍落度值随之减小;普通混凝土与再生混凝土的抗压强度随着砂率的增大趋于平稳;随着砂率增大,同配比条件下的普通、再生混凝土的干燥收缩变化率均有一定程度的增加,120d后逐渐趋于平稳,第180d混凝土的砂率与干燥收缩长度变化率之间存在良好的线性关系。

In order to study the rules of compressive strength and dry shrinkage of recycled concrete conditions under the different sand ratio,in this paper,the replacement rate of recycled coarse aggregate is100%,the recycled concrete strength grade of C30 is taken as an example,the recycled concrete gas content,density,compressive strength and dry shrinkage are tested in different sand ratio conditions,and at the same time compared to the ordinary concrete specimens,the conclusions are as follows：under the conditions of the same ratio,the strength C30 of recycled concrete gas content increases with the increase of sand ratio,the slump value decreases;ordinary concrete and recycled concrete compressive strength with the increase of sand ratio tends to be stable;with the sand ratio increases,the dry shrinkage of recycled concrete with the proportion of ordinary changes,under the conditions of the rate increased to a certain extent,after 120 days gradually stabilized,there is a good linear relationship between concrete sand ratio and dry shrinkage rate of length change at the 180 th day.