含玻璃砂的高性能碱激发矿渣砂浆性能研究

Performance of Glass Sand-Containing High-Performance Alkali-Activated Slag Mortars

采用玻璃砂代替部分细骨料制备碱激发矿渣(AAS)砂浆后,研究了玻璃砂含量(0%、10%、20%、30%,质量分数)对AAS砂浆抗压强度、抗折强度、干燥收缩、导热系数和碱-硅酸反应(ASR)膨胀率的影响,并通过扫描电子显微镜(SEM)对微观机理进行了分析。结果表明:掺10%~30%的玻璃砂能显著提高AAS砂浆的早期抗压强度,但会略微降低28 d抗压强度;AAS砂浆的抗折强度随玻璃砂掺量的增加先增大后减小,10%掺量时最有利于3 d抗折强度,20%掺量时最有利于28 d抗折强度;AAS砂浆的干燥收缩、导热系数和ASR膨胀率均随玻璃砂掺量的增加而减小,与对照组相比,掺30%玻璃砂的AAS砂浆导热系数降低14.4%,56 d干燥收缩率降低27.6%,14 d ASR膨胀率降低39.6%,28 d ASR膨胀率降低34.5%;SEM分析发现玻璃砂表面有水化产物生成,其与胶凝材料的结合比石英砂更紧密,使AAS砂浆的微观结构更加致密。

Some fine aggregates were substituted for glass sand in the preparation of alkali-activated slag(AAS) mortars. The effects of glass sand content(0%, 10%, 20%, 30%, mass fraction) on compressive strength, flexural strength, drying shrinkage, thermal conductivity, and expansion rate of alkali-silicate reaction(ASR) of AAS mortars were tested, and the microscopic mechanism was analyzed by scanning electron microscope(SEM). The results demonstrate that the early compressive strength of AAS mortars can be significantly improved with 10% to 30% glass sand content, but the 28 d compressive strength can be slightly reduced. The flexural strength of AAS mortars increases first and then decreases with the increase of glass sand content.The 10% glass sand content is most favorable to the 3 d flexural strength, while the 20% glass sand content is most favorable to the 28 d flexural strength. With the increase of glass sand content, the drying shrinkage, thermal conductivity and ASR expansion rate of AAS mortars all decrease. The AAS mortar with 30% glass sand content is discovered that it has 14.4% lower thermal conductivity, 27.6% lower 56 d drying shrinkage, 39.6% lower 14 d ASR expansion rate, and 34.5% lower 28 d ASR expansion rate comparing to the control group. Hydration products are created on glass sand surface, and its binding with cementitious material is tighter than that of quartz sand, according to SEM examination, which makes the microstructure of AAS mortar compact.