Research Of Concrete Containing MSWI Bottom Ash And Coal Fly Ash

Incineration of municipal solid waste allows a great reduction in the quantity of the wastes of about80%in mass. Municipal solid waste incineration(MSWI) bottom ash is one of the major by-products, it may causes secondary pollution. The technology of using recycled aggregate to confect concrete not only may resolves the pollution of the environment by bottom ash, but also relieves the contradiction of supply and demand for aggregate. Its efficiency of social environment and economic is notable. The workability and strength of concrete decrease with an increase of bottom ash contents. The coal fly ash is beneficial to properties of concrete. This paper researches the effect of coal fly ash on properties of MSWI bottom ash concrete, resolves the problem of that strength, durability and fluidity decrease because of the large use of bottom ash.This paper studies the chemical and physical properties of raw materials, each concrete mixture ratio considers two influences factors, including coal fly ash and bottom ash. The effect of coal fly ash on the workability of MSWI bottom ash concrete is analyzed. The mechanical properties test are carry out, the effect of coal fly ash on the compressive strength, tensile strength and elastic modulus of MSWI bottom ash concrete is studied, the optimum value of fly ash is obtained. The influence of bottom ash and coal fly ash on the frost resistance and the permeability resistance of MSWI bottom ash concrete is studied. The paper tests pore structure characteristics of concrete by the mercury injection method, studies the influence of the coal fly ash on pore structure, then reveals the mechanism of the effect of fly ash on MSWI bottom ash concrete.The results show that outward appearance of slag in bottom ash is similar to natural gravel, the chemical composition of bottom ash is similar to natural coarse aggregate, the size distribution of bottom ash is well, it is suitable for concrete as aggregate. Reduction of slump occurs when bottom ash is introduced into the aggregate mixture, because of that bottom ash is angular and rough with high porosity. Bottom ash contains needle and flake material, and its crushed index is higher, it effects the mechanical properties of concrete in a certain extent. By adding coal fly ash and high effective water reducer, the MSWI bottom ash concrete can get a good workability, pore structure becomes finer, mechanical properties and durability improve. The mix with20%fly and50%bottom ash gains compressive strength of the order of42.7MPa at90days and frost-resistance grade of F175.