表面处理污泥渣料磨细粉水泥基材料活性激发及其机理

Activation and mechanism of pulverized surface treatment sludge

为了更好地提高掺加表面处理污泥与建筑渣土高温烧结渣料磨细粉(简称磨细粉)的火山灰活性,研究了Ca(OH)_(2)对掺加磨细粉硅酸盐水泥基材料的力学性能和重金属浸出规律的影响及机理,并通过XRD、SEM、BET、TG等微观测试技术分析材料的微细观结构特征。结果表明:Ca(OH)_(2)掺量为磨细粉水泥基材料中胶凝材料总质量的0.6%~0.8%时,磨细粉水泥基材料力学性能较优,在60 d时抗折强度和抗压强度较基准组分别提高了11.0%和7.8%;微细观测试结果表明,少量的Ca(OH)_(2)能增大磨细粉水泥基材料硬化浆体的比表面积,增加水化产物数量,提高硬化浆体结构密实性,但Ca(OH)_(2)掺量超过胶凝材料总质量的0.8%之后,对磨细粉水泥基材料结构和性能则会产生负面效应。研究还发现,掺加占胶凝材料总质量0.8%的Ca(OH)_(2)能有效降低磨细粉水泥基材料中有害重金属的浸出浓度,其中Cu、Ni、Zn浸出率比基准组分别降低了17.5%、13.0%、40.8%,可以确保磨细粉水泥基材料中有害重金属Cu、Ni、Zn和Cr的浸出值均低于《水泥窑协同处置固体废物技术规范》(GB/T 30760—2014)中规定的浸出浓度限值。

In order to to improve the pozzolanic activity of the pulverized powder from the high temperature sintering slag of surface treatment sludge and construction residue,the effect and mechanism of Ca(OH)_(2)on mechanical properties and heavy metal leaching of Portland cement-based materials were studied,and the microstructure characteristics of the materials were analyzed by XRD,SEM,BET,TG and other microscopic testing techniques.The results show that when Ca(OH)_(2)content is 0.6%~0.8%of the total mass of ground powder cement-based materials,the mechanical properties of cement-based materials mixed with grinding powder are better.At 60 days,the flexural strength and compressive strength increased by 11.0%and 7.8%,respectively.Microscopic test results show that a small amount of Ca(OH)_(2)can not only increase the specific surface area of ground powder cement-based materials’hardened slurry,but also increase the number of hydration products,and improve the structural compactness of hardened slurry.However,when the content of Ca(OH)_(2)exceeds 0.8%of the total mass of cement-based hardened slurry,it has a negative effect on the structure and properties of cement-based materials.It is also found that the addition of Ca(OH)_(2)can reduce the leaching concentration of harmful heavy metals in cement-based materials with the addition of the ground powder.The leaching rates of Cu,Ni and Zn were 17.5%,13.0%and 40.8%lower than those of blank group.It can ensure that the leaching values of harmful heavy metals Cu,Ni,Zn and Cr in cement-based materials mixed with grinding powder are lower than the leaching concentration limits specified in the Technical Specification for Coprocessing of Solid Waste in Cement Kiln(GB/T 30760-2014).