Characterization of sustainable mortar containing high-quality recycled manufactured sand crushed from recycled coarse aggregate
Characterization of sustainable mortar containing high-quality recycled manufactured sand crushed from recycled coarse aggregate
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DOI：
10.1016/j.cemconcomp.2022.104629
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发表时间：
2022-09-01
影响因子：
10.5
通讯作者：
Wu, Huixia
中科院分区：
文献类型：
--
作者：
Ma, Zhiming;Shen, Jiaxin;Wu, Huixia
由于再生细骨料中存在大量的硬化旧砂浆，目前利用废弃混凝土中的低品质再生细骨料代替河砂，不能满足配制高品质再生砂浆的要求。本文提出了一种创新的、可行的方法，将再生粗骨料破碎成再生机制砂，使其具有与天然石料破碎后的机制砂相似的高品质性能，从而制备出高强度、高耐久性的高品质再生砂浆。结果表明：再生机制砂由大比例的天然石颗粒和小比例的旧砂浆组成，比再生细骨料具有更高的表观密度和更低的吸水率。再生细集料的掺混增加了再生混凝土的干缩，降低了再生混凝土的强度;再生机制砂取代天然河砂后，由于其形状不规则，表面粗糙，在砂浆中的干燥收缩减小，同时，机械强度随取代率的增加先增大后减小，其中含50%再生机制砂的砂浆表现出最好的机械强度。与再生机制砂的测试砂浆显示出在水和氯化物进入的一般增量，但表现出的吸水性和氯化物的进入远低于砂浆与再生细骨料。特别是，减少再生机制砂中硬化旧砂浆的含量进一步改善了再生砂浆的性能。
The current utilization of low-quality recycled fine aggregate sourced from concrete waste acting as river sand replacement cannot achieve the preparation required for high-quality recycled mortar, due to abundant existence of hardened old mortar in recycled fine aggregate. In this work, an innovative and viable approach is proposed to crush recycled coarse aggregate into recycled manufactured sand, which has high-quality properties similar to the manufactured sand crushed from natural stone, for preparing high-quality recycled mortar with high strength and good durability. The results showed that recycled manufactured sand constituted by large proportion of natural stone particles and small proportion of old mortar, owned higher apparent density and lower water absorption than recycled fine aggregate. Incorporating recycled fine aggregate increased the drying shrinkage and decreased the mechanical strength; however, the substitution of natural river sand by recycled manufactured sand in mortar decreased the drying shrinkage as a result of its irregular shape and coarse surface, meanwhile, first increased and then declined the mechanical strength following the increase of the replacing percentage, amongst which the mortar containing 50% recycled manufactured sand showed the best mechanical strength. The tested mortars with recycled manufactured sand showed a general increment in the water and chloride ingress yet exhibited the water absorption and chloride ingress much lower than the mortar with recycled fine aggregate. Particularly, decreasing the content of hardened old mortar in recycled manufactured sand further improved the properties of recycled mortar.