碎砖瓦再生骨料对再生混凝土性能影响微观分析

Microscopic Approach to Influence of Recycled Aggregate upon Properties of Recycled Concrete

本文通过建立试验模型,将碎砖瓦破碎筛分后制成再生粗细骨料,分别全部和部分替代天然砂石原料配制再生混凝土,并进行混凝土界面过渡区显微硬度测试、硬化混凝土气孔特征分析。研究发现,再生骨料内部显微硬度偏低、再生骨料边缘显微硬度相对较高,因而再生混凝土受载破坏面易发生在再生粗骨料内部;随着再生粗骨料掺量增加,再生混凝土微观孔隙率增大,强度逐渐降低。

Under the conditions that the crushed bricks and tiles are recycled into coarse and fine aggregate respectively so as to completely and partially replace the raw materials of natural sand and stone for making recycled concrete, an experimental model is established to test the microhardness of the recycled concrete interface’s transitional zone, and to analyze the characteristics of the pores in the hardened concrete. The finding shows that the internal microhardness of recycled aggregate is low while the microhardness of the recycled aggregate’s edge is relatively high so that the failure surface of recycled concrete is prone to occur in the recycled coarse aggregate. With the increase in the recycled coarse aggregate content, the recycled concrete shows growing microporosity but declining strength.