Study On The Effect Of MSWI Bottom Ash On The Mechanical Properties Of Mortar And Its Pretreatment

With the guidance of the government policy and the development of waste incineration power generation technology,the proportion of municipal solid waste incineration will increase sustainably.As the inevitable by-product of the incineration,the municipal solid waste incineration?MSWI?bottom ashes are bound to increase sharply,which will bring a series of environment problems correspondingly.How to utilize the MSWI bottom ash in“change waste into energy”has become an urgent problem to be solved in the management of municipal solid waste.In the study of MSWI bottom ash,it was found that the main chemical composition of MSWI bottom ash was similar to that of ordinary Portland cement,and its physical properties were similar to those of natural fine aggregate.Therefore,the replacement of cement or natural fine aggregate with the MSWI bottom ash has great research value,and in some developed countries,the application of incineration bottom ash to the construction industry has been applied.This paper takes the MSWI bottom ash in Chengdu and its surrounding areas as the representative,and studies the pretreatment methods of MSWI bottom ash in southwest China and its influence on the physical and mechanical properties of mortar.Through experimental and theoretical analysis,the characteristics and pretreatment methods of MSWI bottom ash were studied,and the optimal pretreatment scheme for southwest area of China was put forward.On this basis,the influence of MSWI bottom ash,silica fume and fly ash mixed to replace 30%cement in different proportion on mortar performance was studied,and the optimal proportion scheme was obtained.Finally,the effect of different ratio of MSWI bottom ash instead of natural river sand on mortar performance was studied,and the optimal substitution rate was obtained.The main conclusions obtained in this paper are as follows:?1?The MSWI bottom ash in southwest of China can be used as the substitute for natural fine aggregate for its crushing index reaches the type?index of mechanism sand despite complex composition,pore in bottom ash particle,loose structure and low density.?2?The treatment of bottom ash with saturated Ca?OH?₂ solution is a rather better pretreatment scheme that is suitable for the characteristics of MSWI bottom ash in southwest China,which can eliminate the adverse effects of active metals such as aluminum and zinc in bottom ash on mortar performance.The mechanical properties of mortar can be obviously improved by reducing the formation of micro-pore structure and improving the micro-structure of mortar.?3?The optimal ratio scheme is that the 30%ordinary Portland cement was replaced by mixing bottom ash,silica fume and fly ash in the proportion of 1:1:1.The working performance of the mortar made by this ratio scheme is similar to that of the ordinary mortar,and the mechanical strength of the mortar can also reach more than80%of the control mortar,which meets the requirements of standard JG/T 315-2011.It can be used in non-load-bearing structures where mechanical strength requirements are not very high.?4?When the replacement rate of MSWI bottom ash is 10%,the mechanical strength of recycled mortar is basically equal to the standard mortar,even slightly higher than the reference mortar.However,the mechanical strength of recycled mortar began to decrease gradually as the replacement ratio of MSWI bottom ash continued to increase.Therefore,it is considered that the optimal ratio scheme should be between 10%and 20%.