高延性再生骨料碱矿渣复合材料的制备及性能

Preparation and Properties of Highly Ductile Alkali Slag Composites from Recycled Fine Aggregate

摘要: 碱激发矿渣复合材料因其绿色低碳的优点广受关注。然而碱矿渣的制备仍然消耗大量石英砂，石英砂供应短缺和价格上涨，导致了碱矿渣的制备成本增加。由建筑垃圾破碎生产的再生砂因其来源丰富、体量巨大、绿色环保，具有取代石英砂制备碱矿渣的潜力。利用再生细骨料替代石英砂作为骨料掺入到碱激发矿渣复合材料中，制备了更加绿色的高延性的碱激发矿渣复合材料。本文设置0~0.15 mm，0.15~0.3 mm，0.3~0.6 mm，0.6~1 mm四种不同粒径范围的再生细骨料来代替石英砂，通过展开单轴拉伸实验，压缩实验以及纳米压痕表征研究了骨料粒径对碱矿渣力学性能的影响，结合三点抗弯及单裂缝拉伸等细观实验探究其高延性机理。结果表明：不同粒径再生细骨料的掺入都有利于增加碱矿渣的延性，同时又都会造成其强度与裂缝开裂宽度的降低。0.15 mm以下的再生细骨料制备的高延性碱矿渣为最佳。再生细骨料的掺入使得碱矿渣基体的断裂韧性降低，从而导致应变硬化系数PSH = Jb'/Jtip增大，使得复合材料在荷载作用下的应变硬化得以增强。

Abstract: Alkali-inspired slag composites have gained widespread attention for their green and low-carbon advantages. However, the preparation of alkali slag still consumes a large amount of quartz sand, and the shortage of quartz sand supply and price increase have led to an increase in the preparation cost of alkali slag. Recycled sand produced by construction waste crushing has the potential to replace quartz sand in the preparation of alkali slag due to its rich source, huge volume and green environment. The recycled fine aggregate was utilized to replace quartz sand as aggregate blended into alkali excited slag composites to prepare greener and highly ductile alkali excited slag composites. In this paper, four kinds of recycled fine aggregates with different particle sizes ranging from 0 to 0.15 mm, 0.15 to 0.3 mm, 0.3 to 0.6 mm, and 0.6 to 1 mm were used to replace quartz sand, and the effects of aggregate particle size on the mechanical properties of alkali slag were investigated through uniaxial tensile experiment, compression experiment, and nanoindentation characterization, and the mechanism of its high ductility was investigated by combining with the three-point bending resistance and the single-slit stretching and other microscopic experiments. The results show that the incorporation of recycled fine aggregate with different particle sizes is beneficial to the increase of the ductility of alkali slag, and at the same time, it will cause the decrease of its strength and crack opening width. 0.15 mm or less recycled fine aggregate is the best for the preparation of high ductility alkali slag. The incorporation of recycled fine aggregate reduces the fracture toughness of the alkali slag matrix, which leads to an increase in the strain hardening coefficient PSH = Jb'/Jtip, which enhances the strain hardening of the composites under loading.