Behavior of fresh-laid mortars composed of crushed limestone sand and natural sand

ABSTRACT The goal of this resarch is to identify the behavior of limestone crushed sand in coating mortar. Five trace compositions were proposed and tested: the first one made up of 100% natural sand, which will be used as reference trace, the second composition presented 80% natural sand and 20% limestone rock crushed sand, the third one 60% natural sand and 40% limestone rock crushed sand, the fourth one with 40% natural sand and 60% limestone rock crushed sand, and the fifth trace 20 % natural sand and 80% limestone rock crushed sand. The mortar traces were composed of cement, sand, water and additive, without the presence of lime, and these were tested in the wet state and presented the following results: Composite traces with limestone rock crushed sand presented better performance than the reference trace, which had only natural sand. The traces with 60% natural sand and 40% limestone crushed sand showed better performance, and presented a grain size curve within the optimal upper and lower zone, as required by the standard rules. The relevance of this study is due to the fact that crushed sand is a waste that generates important environmental liability. Therefore, the use of this type of waste makes it possible to reduce this environmental impact.摘要 本研究旨在探明石灰石机制砂（limestone crushed sand）在抹灰砂浆（coating mortar）中的应用行为。本次试验共设计并测试了5组配合比试样：第一组为100%天然砂，作为基准试样；第二组为80%天然砂与20%石灰石机制砂复配；第三组为60%天然砂与40%石灰石机制砂复配；第四组为40%天然砂与60%石灰石机制砂复配；第五组为20%天然砂与80%石灰石机制砂复配。所有砂浆试样均由水泥、砂、水及外加剂配制而成，未掺入石灰，且均在湿态条件下开展性能测试，测试结果表明：掺加石灰石机制砂的复合配合比试样性能优于仅采用天然砂的基准试样。其中，60%天然砂与40%石灰石机制砂的复配试样性能最优，其颗粒级配曲线处于标准规范要求的最优上下限区间内。本研究的意义在于，石灰石机制砂属于会产生显著环境负荷的废弃物，通过该类废弃物的资源化利用，可有效降低其对应的环境影响。