Experiment Of Recycling MSW As Light Weight Aggregates

With the development of society and improvement of national lives,the large quantity of municipal solid waste(MSW) has threatened ecological environment and human's life. Now, the disposal and recycle of MSW mainly centers around landfill, incineration and compost in our country, but the organic fraction of MSW is putrescible, high moisture-content, high organic-content and so on, it is hard to achieve goal of"harmlessness, resources, quantitative reduction"by normal treatments. Thus, actively explore a new way of reutilization of MSW seems particularly important.The chemical composition, elemental composition and calcination prosperity of organic fraction of MSW were analyzed; the results indicated that it couldn't be uses as raw material to prepare light weight aggregates (LWA) respectively. Comprehensive consideration on the chemical composition and requirements for prepare LWA of raw materials, MSW, coal fly ash and clay were selected to be as raw materials to prepare LWA.The best optimum batch formula (dry mixture ration) was obtained through formula uniform restricted design theory, namely 15.38% of BMW,69.77% of coal fly ash ,14.85% of clay. The optimal calcination conditions were obtained through orthogonal experimental design method, namely preheating temperature of kiln is 500℃, sintering temperature is 1190℃, holding time of sintering temperature is 4min. The performance testing indicators of aggregate with the best optimum batch formula and optimal calcination condition shows: bulk density is 605kg/m3, cylinder compressive strength is 3.0MPa, 1hr water absorption is 11.0%, apparent density is 0.93, all of the targets meet 700 grade light aggregate of GB/17431.2 -1998 standards.Leaching tests have also been carried out to assess the potential environmental impact of utilisation. The results of leaching test below hazardous constituent's concentration limits of hazardous waste identification standard(GB/T 5083.3-2007),integrated wastewater discharge standard(GB8978-1996),landfill standard (GB16889-2008),so it will not result in secondary pollution, it is not hazardous to environment. The LWA produced were tested by incorporation in to concrete as coarse aggregate replacement. The concrete dry apparent density is 1840kg/m3; 28-day compressive strength is 32.1MPa, achieves strength grade CL45. It can be applied to Industrial or civil building project, also bring remarkable economic benefits, environmental benefits and social benefits.