Experimental Study Of Municipal Solid Waste Incineration Fly Ash And Iron Ore Tailings In Asphalt Pavement Base Course

As the economy develops,the continuous increase in steel production will be accompanied by the increasing amount of iron ore tailings(IOT).If it is not disposed of properly,it will not only occupy land but also cause environmental pollution and pose safety hazards.With the continuous improvement of urban living standards and the rapid progress of urbanization,the amount of urban household waste is also increasing year by year.Incineration has become an effective method for treating household waste.Incineration can reduce the volume and weight of waste,but it also produces a large amount of Municipal Solid Waste Incineration(MSWI)fly ash containing heavy metals and dioxins.Improper disposal of MSWI fly ash can also cause environmental pollution and harm residents health.In order to achieve the synergistic disposal and resource utilization of hazardous solid waste such as MSWI fly ash and bulk solid waste IOT,a study on using them in pavement base course is carried out in this paper.Cement and fly ash(1:3 ratio)were used as stabilizing materials,while IOT was used as aggregate,while MSWI fly ash was used as a part of the cementitious material or as a partial replacement for the aggregate.The study conducted tests for unconfined compressive and indirect tensile strength,dry and temperature shrinkage,and toxic leaching,and used SEM-EDS and XRD for microscopic analysis.The following conclusions were drawn: After replacing part of the iron tailing sand with MSWI fly ash,the content of active substances was increased,and the strengths all increased,and there was secondary hydration at a later stage,with higher strength development;after replacing 10% of cement and fly ash with two types of MSWI fly ash,the unconfined compressive strength of the specimens was reduced;The 90 d splitting strength of only YJ-10 is lower than the 1.18 MPa of KB group,while the strength of other mix proportions was increased;The dry shrinkage of specimens with MSWI fly ash increased compared with those without MSWI fly ash.The stability coefficient of original gray samples decreased significantly after freeze-thaw cycles.The leaching results of toxic substances showed that the MSWI fly ash raw material had the highest content of Pb and Zn,which were easy to diffuse into the environment and affect the surrounding environment.The leaching rate was high at 7 days,but after cement solidification and adsorption of IOT,the leaching rate of various heavy metals was significantly reduced and much lower than the national standard threshold.The use of IOT and MSWI fly ash as materials for pavement base course can bring significant economic and social benefits.