含重金属矿山酸性废水中和沉渣对水泥基材料性能的影响

Effect of Neutralized Sludge of Acid Mine Drainage Containing Heavy Metal on Properties of Cement-Based Materials

研究了采用铜矿酸性废水中和沉渣取代天然石膏对水泥基材料物理力学性能的影响。结果表明,随沉渣掺量的增加,水泥标准稠度用水量略有增加,初凝和终凝时间均大幅延长,掺量为6.5%时,水泥初凝和终凝时间分别长达363和625min,强度呈先增大后减小趋势,与掺天然石膏硅酸盐水泥(PI)相比,掺中和沉渣有助提高水泥强度,其原因是由于铜矿酸性废水中和沉渣中含化学沉淀石膏和重金属Zn2+所致。利用中和沉渣中重金属Zn2+对水泥的缓凝作用,可制备超缓凝水泥(SRC),直接用于配制低坍落度损失高性能混凝土,与掺天然石膏硅酸盐水泥混凝土相比,配合比相同条件下,其初始坍落度较小,但坍落度损失小,而3d和7d强度分别提高22.8%和36.7%。

Effect of replacing natural gypsum with neutralized sludge of acid mine drainage on physical and mechanical properties of the cement-based materials has been investigated. The results show that the consistency was increased; both the initial and the final setting time of the cement were prolonged and the strength was enhanced firstly and then decreased, with increasing the sludge content. When the sludge usage was 6.5%, the initial and the final setting time reached as long as 363 min and 625 min due to the existence of the zinc ions in the sludge, but the strength of the mortar by the sludge was enhanced, as compared with that by using natural gypsum. Thus super-retarded cement (SRC) can be prepared through making full use of the super-retarding effect of zinc ions, which can be directly used to mix concrete under requirement of longer setting time and low slump loss. Under the same mix proportions, the initial slump of the HPC made with the SRC was inferior, but the slump loss was lower, and the strength was enhanced as high as 22.8% and 36.7% at curing age of 3 d and 7 d, as compared with that with the cement using natural gypsum.