Surface Modification Of MSWI-BAA And Application Research Used In Permeable Asphalt Pavement

With the rapid development of highway construction and the country’s restriction on aggregate mining,road materials are seriously lacking.It is one of the effective ways to solve the current dilemma to apply solid waste instead of natural aggregate in road engineering.With a large population base,the output of domestic waste increases year by year.As a by-product of domestic waste incineration,the output of municipal solid waste incinerated bottom ash(MSWI-BA)also increases.The composition of domestic waste is complex,which leads to the variation of MSWI-BA.The MSWI-BA contains similar mineral composition to the natural aggregate and has the potential to be used as road aggregate.However,the chemical reaction of MSWI-BA in the incineration stage makes its micropores fully developed,resulting in the basic properties of municipal solid waste incinerated bottom ash aggregate(MSWI-BAA)compared with natural aggregate has a certain gap.In this paper,the surface modification of MSWI-BAA is carried out to improve the basic performance of slag aggregate.The effects of modified materials on crushing value,apparent density and water absorption of MSWI-BAA at different concentrations and drying temperatures were studied by orthogonal experiment.The optimum modified material was determined by range analysis and adhesion test with asphalt.Based on the design of the permeable asphalt concrete,the modified MSWI-BAA is used in permeable asphalt concrete with different particle size and substitution rate.According to the test results,the best scheme of modified MSWI-BAA in permeable asphalt concrete is determined.Surface modification can improve the basic properties of MSWI-BAA,so as to increase the replacement rate of MSWIBAA in engineering application.Increasing the consumption of MSWI-BAA in highway engineering is helpful to promote the resource utilization.The main research conclusions are as follows:(1)Determine the best surface modification scheme of MSWI-BAA.Orthogonal test was designed for three kinds of modified MSWI-BAA with different drying temperature(100℃,140℃,180℃)and modified material concentration(5%,10%,15%).The results show that10% magnesium oxide is the best modified material for MSWI-BAA.(2)Design of mixing ratio of magnesia modified MSWI-BAA permeable asphalt concrete.Based on the standard design method of permeable asphalt concrete,the optimum asphalt dosage of 1.18～2.36 mm and 2.36～4.75 mm modified MSWI-BAA is determined when the replacement rate is 10%,20%,30%,50% and 70%.The results show that the results show that the gradation design for: 13.2(9.6%): 9.5(30.8%): 4.75(39.6%): 2.36(6.7%): 1.18(2.5%): 0.6(5.0%): 0.3(1.8%): 0.15(1.0%): 0.075(2.5%).When the aggregate replacement rate of modified MSWI-BAA with 1.18～2.36 mm particle size increases by 10%,the optimal asphalt content increases by about 0.08%.when the aggregate replacement rate of modified MSWIBAA with a particle size of 2.36～4.75 mm increases by 10%,the optimal asphalt content increases by about 0.06%.(3)Magnesium oxide modified MSWI-BAA is used to test the pavement performance of permeable asphalt concrete.According to the relevant technical requirements of the(CJJ/T190-2012),the road performance of two particle sizes under the corresponding replacement ratio were tested.The optimal replacement rate scheme of two kinds of particle size modified MSWI-BAA used in permeable asphalt concrete is as follows: MSWI-BAA with particle size of 1.18～2.36 mm,replacement rate of 30%,and MSWI-BAA with particle size of 2.36～4.75 mm,replacement rate of 20%.