污泥-稻壳-木屑混烧灰胶凝性能及重金属浸出特性研究

Experimental Study on Cementitious Properties and Heavy Metal Leaching Characteristics of Sewage Sludge-rice Husk-wood Sawdust Co-combustion Ash

利用污泥-稻壳-木屑混烧灰、钢渣粉以及水泥等材料制备复合胶凝材料。针对制备的胶凝材料胶砂混合料的工作性、胶砂试件强度、水化热、水化产物以及重金属毒性浸出开展了研究工作。结果表明,混烧灰与钢渣粉的掺入改变了水泥胶砂混合料的工作性,与纯水泥试件相比,复合胶凝材料的胶砂试件的抗压抗折强度均有所下降,混烧灰的掺量不宜超过50%。替代材料的掺入,使得水化的诱导期延长,主放热峰向右偏移,说明水化过程的推迟。由于火山灰效应的存在,使得复合胶凝材料体系的累积水化放热量增大。XRD定量分析结果表明复合胶凝材料的水化产物最主要为无定形相,复合胶凝材料的自胶凝固化作用抑制了混烧灰中主要重金属元素迁移性,浸出浓度指标均满足污水排放要求。

This work focused on preparation of cementitious materials by co-combustion ash of sewage sludge-rice husk-wood sawdust.The workability,strength,hydration and heavy metal leachability were investigated.The results show that the workability of fresh mortar is influenced by co-combustion ash.Compared to OPC samples,the strength of composite cementitious materials mortar slightly decreases by adding co-combustion ash.It is suggested that the content of cocombustion ash was no more than 50%.With an addition of co-combustion ash,the induction period during hydration prolonged and main exothermic peak move right.Due to existence of pozzolanic effect,the cumulated hydration heat increased at the later period of hydration.Quantitative analysis of XRD illustrates the main hydration product of composite cementitious materials is amorphous phase.After stabilization and solidification process,the mobility of heavy metal existing in cocombustion ash is controlled and the release of leached heavy metal reaches the requirement of emission regulation.