高强页岩轻骨料混凝土制备及微观结构研究

Study on preparation and microstructure of high strength shale lightweight aggregate concrete

基于最紧密堆积理论和最小需水量法进行高强页岩轻骨料混凝土配合比设计与制备,研究了水胶比对抗压及劈裂抗拉强度影响,并借助SEM/EDS进行微观测试分析。结果表明:当粗细骨料体积分数比为5.5:4.5时,粗细骨料达到最紧密堆积状态;当硅灰、粉煤灰和水泥质量比为0.8:3.2:6时,需水量最少,粉体材料密实度最佳;依据优化配比所配混凝土的抗压强度和劈裂抗拉强度均随龄期增加而增加;随着水胶比增加,抗压强度和劈裂抗拉强度呈先增后减的趋势,且当水胶比为0.24时达到最大,分别为70.9、5.83MPa;硅灰和粉煤灰特有的形态效应和火山灰效应有效改善了浆体与骨料间界面的密实程度,微观结果显示浆体与骨料界面区域结构致密,陶粒区域为富Si、Al相,浆体一侧为富Ca相。

Based on the closest packing theory and the minimum water demand method,the mix ratio design and preparation of high strength shale lightweight aggregate concrete were carried out.The influence of water-binder ratio on compressive and splitting tensile strength was studied,and the microscopic test analysis was carried out by SEM/EDS.The results show that when the volume fraction ratio of coarse and fine aggregate is 5.5:4.5,the coarse and fine aggregate reaches the most closest packing state.When the mass ratio of silica fume,fly ash and cement is 0.8:3.2:6,the water demand is the least and the density of the powder material is the best.The compressive strength and splitting tensile strength of the concrete based on the optimized ratio increase with age.With the increase of water-binder ratio,the compressive strength and splitting tensile strength increase first and then decrease,and reach the maximum when the water-binder ratio is 0.24,which are 70.9MPa and 5.83MPa,respectively.The unique morphological effect and pozzolanic effect of silica fume and fly ash effectively improve the compactness of the interface between slurry and aggregate.The microscopic results show that the structure of the interface between slurry and aggregate is dense,the ceramsite area is rich in Si and Al phases,and the slurry side is rich in Ca phase.