Study on the Synergistic Preparation of Soil Curing Agent and Curing Mechanism by Multi-source Solid Waste
In order to realize the high-value and large-scale utilization of metallurgical solid waste materials,the soil curing agent was synergistically prepared by using metallurgical solid waste materials(blast furnace slag,fly ash,calcium carbide slag and gyp-sum),and the effects of different solid waste materials on the mechanical properties of the cured soil were investigated by orthogonal ratio optimization experiments and the optimal parameter formulations were obtained.The mechanical properties(unconfined compres-sive strength,splitting strength,delayed molding)and weathering properties(water stability,freeze-thaw cycle)of the solidified soil with solid waste-based curing agent(SWC)were systematically studied and compared with PO 42.5 silicate cement(OPC).The re-sults showed that:calcium carbide slag played an important role in the curing agent system,and the appropriate gypsum dosage had a positive effect on the strength growth;the strength of cured soil increased with the increase of SWC dosage and the age of curing,and the 7 day unconfined compressive strength of the cured soil at 4%dosage was more than 1 MPa,and the splitting strength was basi-cally comparable to that of the OPC cured soil;the SWC cured soil showed a longer allowable delay in construction,and there was no trend of decreasing strength within 12 h after mixing;the water stability coefficient was more than 90%when the dosage was more than 5%,and the anti-freezing coefficient under the same dosage was increased by 3%-5%compared with that of cement,so it had good water stability and anti-freezing property;X-ray Diffraction(XRD)and Scanning Electron Microscope(SEM)analyses showed that SWC cured soils generate expansionary hydration products,calcite alumina(AFt)and hydrated calcium silicate(C-S-H),during the hydration process,and that calcite crystals played a significant role in improving the cleavage strength of cured soils and increasing the resistance to cracking and deformation.
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