Study On The Preparation And Long-term Mechanical Properties Of Municipal Solid Waste Incineration Fly Ash Based Filling Material

With the growing number of people in cities,there is a clear upward trend in the production of municipal domestic waste.The incineration of domestic waste reduces the volume by approximately 90% and the mass by 70%,making it an ideal way to dispose of waste.Fly ash from waste incineration is a solid waste with hazardous properties of heavy metals and the issue of proper placement of fly ash needs to be addressed.At the same time,China has a large number of mining areas,and the scientific treatment of waste incineration fly ash can be used for backfilling of mining areas to solve the problems of insufficient filling material and no place to deposit waste incineration fly ash.In this paper,waste incineration fly ash is supplemented by granulated blast furnace slag,which is alkali excited to prepare waste incineration fly ash based mine filler material,and the physical and mechanical properties and microstructure of polymer slurry and stone body are tested.The optimum ratio was selected in relation to the manufacturing cost.Finally,the longterm mechanical properties of waste incineration fly ash-based filling materials were investigated by conducting uniaxial and normal triaxial creep tests on the optimum ratio.The main findings are as follows:(1)The effect of the amount of waste incineration fly ash,the amount and modulus of alkaline exciter on the setting time,rheological properties,compressive strength and heavy metal leaching concentration of the filling material was studied.(2)The curing forms and curing processes of the heavy metals Pb,Cr and Cd were explored by means of microscopic tests such as XRD,FTIR,ICP-MS and SEM-EDS,and chemical equations for the curing of the heavy metals were obtained.The state of the materials at the microscopic level was also observed,and the macroscopic mechanical properties were further interpreted in terms of microstructure.(3)Uniaxial and conventional triaxial creep tests were carried out on the optimum ratio to explore the effects of axial and circumferential pressure variations on the long-term mechanical properties of fly ash-based fill materials for waste incineration.The creep instantonal equations were developed to describe the fly ash-based filling materials and the forms of the equations were derived for the one-and three-dimensional states.(4)The numerical model of the filling material was established using the discrete element software PFC3 D,and the simulation reproduced the particle motion and displacement changes of the cemented filling body under conventional triaxial compression conditions,and analysed the laws and principles of the influence of the surrounding pressure and axial pressure on the axial displacement of the filling material.Finally,the accuracy of the failure mode of the specimen under different load combinations in the test was verified.(5)Midas GTS NX analysis software was used to model the ground,the extraction zone,the proposed building and the filling material,to simulate the ground settlement before and after the filling of the extraction zone under realistic working conditions,and to investigate the necessity of filling the extraction zone and the reliability and long-term stability of the fly ash-based filling material.The paper has 49 figures,19 tables and 81 references.