Meng Tao, Wei Huadong, Yang Xiufen, Zhang Bo, Zhang Yuncai, Zhang Cungui
College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China.
Ocean Research Center of Zhoushan, Zhejiang University, Zhoushan 316021, China.
Materials (Basel). 2021 May 18;14(10):2631. doi: 10.3390/ma14102631.
Mixed recycled aggregate (MRA) is a kind of recycled aggregate containing discarded bricks and other impurities that is inferior to ordinary recycled concrete aggregate. To study the effect of MRA in concrete, specimens with 100% MRA under different water-cement ratios (W/C) of 0.50, 0.42, 0.36 and 0.30 were prepared, and the mechanical properties and microstructure were tested. Results show that compared with ordinary concrete, the compressive strength of mixed recycled aggregate concrete (MRAC) with the same W/C was reduced by more than 50% at 28 days, but the axial compression ratio was relatively high, reaching over 0.87. Affected by the high water absorption of MRA, the hydration rate of cement slowed, which was beneficial to the long-term development of the properties of MRAC. An appropriate increase in cement content could strengthen MRA and densify the pore structure of MRAC. The research results of this article prove that MRA has high utilization value and could be used to prepare MRAC with application potential using optimal gradation, which is of positive significance for promoting the consumption of construction waste.
混合再生骨料（MRA）是一种含有废弃砖块和其他杂质的再生骨料，其性能低于普通再生混凝土骨料。为研究MRA在混凝土中的作用，制备了水灰比（W/C）分别为0.50、0.42、0.36和0.30的100% MRA试件，并对其力学性能和微观结构进行了测试。结果表明，与普通混凝土相比，相同W/C的混合再生骨料混凝土（MRAC）在28天时抗压强度降低了50%以上，但轴压比相对较高，达到0.87以上。受MRA高吸水率的影响，水泥水化速率减缓，这有利于MRAC性能的长期发展。适当增加水泥用量可以增强MRA并致密化MRAC的孔隙结构。本文的研究结果证明，MRA具有较高的利用价值，通过优化级配可用于制备具有应用潜力的MRAC，这对促进建筑垃圾的消纳具有积极意义。
