Abstract

In this study, a new hybrid technique called ‘soaking in mild acetic acid followed by mechanical grinding’ has been introduced to produce treated recycled aggregate (TRA) extracted from construction and demolition (C&D) waste. In this treatment technique, 17.98% of adherent mortar was removed from untreated recycled aggregate (RA). Two different types of mineral admixtures viz: silica fume (SF) and portland pozzolana cement (PPC) were used to improve the microstructure and to strengthen the interfacial transition zone (ITZ) of RA. In this work, 100% natural aggregate (NA) was replaced with four different types of aggregates viz: TRAs (TRA_(SF), TRA_(PPC), TRA) and RA at four different water-cement (w/c) ratios (i.e. 0.45, 0.55, 0.65 and 0.75). Fresh, hardened, and durable concrete properties were like slump, compressive strength, tensile strength, flexural strength, elastic modulus, sorptivity, chloride ion permeability, surface resistivity, etc.; microstructure was analyzed and compared with test results of natural aggregate concrete (NAC). Experimental results indicate that concrete made with TRAs showed better results than concrete made with untreated RA. Based on test results, NA substitution with TRAs is possible with reduced compressive strength for lower to medium strength concretes if designed appropriately.

摘要

在这项研究中，引入了一种称为“浸泡在温和乙酸中然后进行机械研磨”的新型混合技术，以生产从建筑和拆除 (C&D) 废物中提取的处理过的再生骨料 (TRA)。在这种处理技术中，从未经处理的再生骨料 (RA) 中去除了 17.98% 的粘附砂浆。两种不同类型的矿物外加剂即硅灰 (SF) 和波特兰火山灰水泥 (PPC) 用于改善微观结构并加强 RA 的界面过渡区 (ITZ)。在这项工作中，100% 天然骨料 (NA) 被四种不同类型的骨料取代，即：TRAs (TRA _(SF) , TRA _(PPC), TRA) 和 RA 在四种不同的水灰比 (w/c) 下（即 0.45、0.55、0.65 和 0.75）。新鲜、硬化和耐久的混凝土性能，如坍落度、抗压强度、抗拉强度、弯曲强度、弹性模量、吸附率、氯离子渗透率、表面电阻率等；对微观结构进行了分析，并与天然骨料混凝土（NAC）的试验结果进行了比较。实验结果表明，用 TRA 制成的混凝土比用未经处理的 RA 制成的混凝土表现出更好的效果。根据测试结果，如果设计得当，可以用 TRA 替代 NA，同时降低中低强度混凝土的抗压强度。