Research on the Mix Proportion, Admixtures Compatibility and Sustainability of Fluidized Solidification Soil Coordinated with Multi-Source Industrial Solid Wastes

To promote the resource utilization of industrial solid waste, this study developed a multi-source industrial solid waste cementitious material (MSWC) for fluidized solidified soil (FSS), which consists of steel slag (SS), granulated blast furnace slag (GBFS), circulating fluidized bed fly ash (CFBFA), desulfurization gypsum (DG) and ordinary Portland cement (OPC). Firstly, the influence of industrial solid waste contents on the unconfined compressive strength (UCS) of FSS solidified with MSWC (MSWC-FSS) was studied, and the optimal proportion for MSWC was determined as SS:GBFS:CFBFA:DG:OPC = 20:40:15:5:20. Then, the effects of water reducers (PCE and FDN) and early-strength agents (Na2SO4 and CaCl2) on the flow expansion, setting time and UCS of MSWC-FSS were studied. With the increase of PCE and FDN, the flow expansion, setting time and UCS of MSWC-FSS increased. With the increase of Na2SO4 and CaCl2, the flow expansion and setting time of MSWC-FSS decreased, and 3 d and 7 d UCS increased, and 28 d UCS first increased and then decreased. The best mixing scheme of water reducer and admixture is 0.5% PCE and 1% Na2SO4, respectively. Finally, the sustainability of MSWC-FSS was assessed. The heavy metal leaching of MSWC-FSS met the safety requirements. For FSS cementitious materials, the cost and carbon emissions of MSWC were only 43.9% and 22.4% of OPC, respectively.