低吸水率陶瓷再生砂对砂浆力学和干燥收缩性能的影响及机理研究

Effect and Mechanism of Low Water Absorption Ceramic Recycled Sand on Mechanical and Drying Shrinkage Properties of Mortar

为了解决废弃陶瓷再生利用和河砂短缺的问题,开展了低吸水率陶瓷再生砂(由废弃低吸水率瓷质陶瓷墙地砖制备而成,简称陶瓷砂)的性能及其等体积全取代河砂对砂浆力学和干燥收缩性能的影响研究。结果表明:陶瓷砂的吸水率、表观密度和压碎指标均较低,是一种轻质高强的细骨料;在水胶比、胶凝材料组成和砂浆工作性能相同的情况下,与河砂砂浆相比,水胶比为0.45、0.35和0.25的三种陶瓷砂砂浆的力学性能均明显提高,其中28 d抗压强度分别提高了39.1%、26.8%和24.6%,且28 d干燥收缩值分别降低了45.7%、17.9%和5.3%;水胶比越大,陶瓷砂砂浆的抗压强度、抗折强度和弹性模量提高幅度越大,干燥收缩值降低幅度越大。性能改善的机理是陶瓷砂自身强度高,陶瓷砂表面粗糙并含有1~20μm的微孔,且含有大量1~5μm的微粉,以其取代河砂后改善了砂浆中界面过渡区和水泥石的微观结构。

In order to solve the problem of waste ceramic recycling and river sand shortage,a study on the properties of low water absorption ceramic recycled sand(prepared from waste low absorption porcelain ceramic tiles,referred to as ceramic sand)and the effect of equal volume fully replacing of river sand on the mechanical and drying shrinkage properties of mortar was carried out.The results show that ceramic sand has a low water absorption,apparent density and crushing index,which is a light and high strength fine aggregate.Under the same water-binder ratio,cementitious material composition and working performance,compared with river sand mortar,the mechanical properties of three ceramic sand mortars with water-binder ratio of 0.45,0.35 and 0.25 are significantly improved,in which the 28 d compressive strength increases by 39.1%,26.8% and 24.6%,and the 28 d drying shrinkage value decreases by 45.7%,17.9% and 5.3%,respectively.The larger the water-binder ratio is,the greater the increase in compressive strength,flexural strength and elastic modulus of ceramic sand mortar are,and the greater the decrease in drying shrinkage value is.The performance improvement is due to the properties of ceramic sand with high strength,rough surface,containing micropores from 1μm to 20μm and a large number of micro-powders from 1μm to 5μm,which improve the interfacial transition zone and the microstructure of cement stone in mortar after replacing river sand with ceramic sand.