Abstract

This work studied the compressive behavior and microstructure of cement-based recycled concrete (CE-RC), low-volume fly ash (FA) recycled concrete (LFA-RC), and high-volume FA recycled concrete (HFA-RC) under different curing ages. The compressive properties, energy absorption properties, and microstructure of CE-RC, LFA-RC, and HFA-RC were measured and compared with cement-based normal concrete (CE-NC). The addition of coarse recycled concrete aggregate (CRCA) leads to more macropores and micro cracks in the concrete. As the result, the mechanical property of RC is worse than normal concrete. FA improved the energy absorption performance of recycled concrete in the early stage. With the continuous curing, pozzolanic reaction occurred between FA and the cement hydration product. The internal microstructure of LFA-RC and HFA-RC was improved. However, part of the FA in HFA-RC can only act as a filler and cannot fully participate in the secondary hydration reaction. Therefore, in the mature age, the internal pore distribution of LFA-RC was the most uniform. And the improvement of strength is more obvious.

摘要

本工作研究了水泥基再生混凝土（CE-RC）、低掺量粉煤灰（FA）再生混凝土（LFA-RC）和高掺量FA再生混凝土（HFA-RC）在不同条件下的压缩行为和微观结构。治愈年龄。测量了 CE-RC、LFA-RC 和 HFA-RC 的压缩性能、能量吸收性能和微观结构，并与水泥基普通混凝土 (CE-NC) 进行了比较。添加粗再生混凝土骨料 (CRCA) 会导致混凝土中出现更多的大孔和微裂缝。结果，RC的力学性能比普通混凝土差。FA在早期提高了再生混凝土的吸能性能。随着持续养护，FA与水泥水化产物发生火山灰反应。LFA-RC和HFA-RC的内部微观结构得到改善。然而，HFA-RC 中的部分 FA 只能起到填充剂的作用，不能充分参与二次水合反应。因此，在成熟期，LFA-RC内部孔隙分布最为均匀。而且实力的提升更加明显。