Recycling Of Municipal Solid Waste Incineration Bottom Ash In Asphalt Mixtures

With the increase of population and the improvement of people’s living standard,the output of municipal solid waste is increasing constantly.The problem of accumulation of municipal solid waste has begun to affect people’s normal life.One third of the cities in China have been surrounded by garbage.It is urgent to solve the problem of garbage accumulation.Municipal solid waste incineration(MSWI),as one ofthe harmless treatment methods of municipal domestic waste,can significantly reduce the volume of municipal solid waste by about 90%.It plays an increasingly important role in municipal solid waste treatment.It is the main research direction of domestic waste treatment in recent years.MSWI bottom residue is the main component of the residue produced after waste incineration,accounting for 80% of the total residue mass.In this paper,the basic physical and chemical properties of MSWI bottom ash and limestone aggregates are studied by experiments.The AC-16 asphalt mixtures,commonly used in highway construction,is selected as the research object.Pauli 70 road asphalt,natural limestone mineral aggregates from Huatian gravel yard in Changde City,Hunan Province,and MSWI bottom ash from Jinlia Environmental Protection Technology Co.,Ltd.in Zhuzhou City,Hunan Province are selected as raw materials.The optimum asphalt content of four asphalt mixtures with different MSWI bottom ash contents(0,10%,20% and 30%)is determined by Marshall mix design.Through a series of tests such as Marshall test,rutting test,low temperature splitting test,immersion Marshall test and freeze-thaw splitting test,the main road performances of asphalt mixtures with 0,10%,20% and 30% MSWI bottom ash is analyzed in detail.The main conclusions are as follows:(1)The particle size range of MSWI bottom ash is the same as that of the natural limestone stone chip used in the experiment,and the screening residual percentage is the same.The surface of MSWI bottom ash is porous and uneven.The surface of limestone stone chip is smooth and compact.The apparent relative density,surface dry relative density and gross volume relative density of MSWI bottom ash are slightly smaller than those of limestone stone chip,and the water absorption rate is higher than that of limestone stone chip.The main constituent elements of MSWI bottom ash are the same as limestone stone chip,and there are more kinds of chemical constituent elements in the limestone stone chip.(2)The optimum asphalt dosage of the 0%,10%,20% and 30% MSWI bottom ash asphalt mixtures are 4.38%,5.14%,5.63% and 6.21%,respectively.With the increase of MSWI bottom ash content,the gross volume relative density of the asphalt mixtures decreases gradually,the air voids,Marshall stability and flow value increase gradually,and VMA first increases and then decreases.When the MSWI bottom ash content is 20%,the VMA value of the asphalt mixtures reaches the maximum.(3)With the increase of MSWI bottom ash content,the high temperature stability of asphalt mixtures increases first and then decreases.When the MSWI bottom ash content is 10%,the high temperature stability of asphalt mixtures is the best.With the increase of MSWI bottom ash content,the low temperature crack resistance is gradually improved,and the water stability is weakened little by little.Considering all kinds of factors,adding 10% MSWI bottom ash is recommended as the optimum MSWI bottom ash content in asphalt mixtures.