高掺量矿渣砂浆的力学强度、耐久性及生态效率评价

为充分发挥矿渣混凝土的绿色环保的优点,加快高掺量矿渣混凝土的应用,使用矿渣取代80%水泥制备了矿渣生态砂浆,利用硅粉作为基本性能调控材料,研究了硅粉掺量与矿渣砂浆力学和耐久性能的关系,并评价了矿渣砂浆的生态效率。研究结果表明,硅粉有助于缓解高掺量矿渣砂浆的缓凝问题,在10%硅粉掺量下,矿渣砂浆的凝结时间与基准组相近。另外,硅粉可显著改善矿渣砂浆的力学强度和耐久性,在最优掺量组 (5%)中,矿渣砂浆的28 d抗压强度和抗折强度均高于基准组。矿渣与(2.5%~10%)硅粉复掺时,砂浆的毛细吸水率降幅为8.83%~26.81%,电通量降幅为5.28%~36.87%。本研究通过使用矿渣和硅粉共同取代80%水泥,有效改善了矿渣砂浆的基本性能,提升了其生态效率,可为矿渣生态混凝土的应用与发展提供理论依据。

Mechanical Strength,Durability and Evaluation of Ecological Efficiency of Mortar with High Volume of Slag

To make full use of the prominent green feature of slag concrete and accelerate its practical application, we adopted silica fume as the strength adjustor to investigate its effect on the mechanical strength and durability of mortars with 80% slag. We also evaluated the ecological efficiency of slag mortars. Experimental results demonstrate that silica fume is such an effective material to mitigate the retarded setting of mortars with high amount of slag due to dilutive effect. When 10% silica fume was added, the setting time of slag mortar was close to that of the control group. Moreover, silica fume has exerted prominent effects on the mechanical strength and durability of mortars. With 5% silica fume added, both the 28-day compressive strength and the flexural strength of mortar were much higher than those of mortar without silica fume. Consequently, the durability of mortar was also greatly improved by incorporating slag and silica fume into mortars, i.e., the capillary water absorption and electric flux of mortar reduced 8.83%-26.81% and 5.28%-36.87%, respectively. In summary, through the combined use of slag and silica fume as the alternative to 80% cement to prepare mortars, we significantly ameliorated the performance of slag mortars as well as its ecological efficiency, hence providing theoretical basis for the application and development of concrete with high volume of slag.