| Recent years has witnessed the increasing amount of household waste becoming a serious social problem in the whole country and even the entire world with major treatment methods including composting,landfill and incineration,which,as it can achieve the capacity reduction of domestic waste to a large extent,has become the main way for dealing with domestic.However,after incineration,there is about 20%of the total incineration ash remaining,making how to realize the resource and industrial utilization of incineration ash an urgent problem to be solved.Meanwhile,global warming caused by greenhouse gas emissions,among which carbon dioxide is the greenhouse gas with the biggest impact on global warming,can lead to catastrophic consequences for the planet.The cement industry accounts for 5-7%of global carbon emissions and is expected to grow significantly in the later stage.In this regard,the research group proposes to conduct an applied research on the municipal solid waste incineration bottom ash in concrete,and considers this test as a sub-topic for analysis,with preliminary research results showing that the main chemical composition of municipal solid waste incineration bottom ash(hereinafter referred to as MSBIBA)is similar to granulated blast furnace slag(hereinafter referred to as GBFS),which has potential hydration,but the hydraulic play is not obvious,making it feasible to be used as concrete admixture.In view of this,referring to the GBFS slag method,the molten water quenching test of ash is put forward in this thesis,obtaining the water quenching municipal solid waste incineration bottom ash powder(hereinafter referred to as:WQ-MSWIBA powder),and the WQ-MSWIBA powder is tested and studied as concrete admixture.The main research contents include:molten water quenching treatment of MSWIBA,the properties of WQ-MSWIBA material,microhole structure and micromechanical properties as well as an analysis on the correlation between macromechanical properties and microhole structure of micropowder concrete employing the grey theory.The feasibility of WQ-MSWIBA powder used as concrete admixture is analyzed from the macro and micro perspectives thus providing reference for its application as concrete admixture,with conclusions as follows:(1)The optimal melting temperature of MSWIBA is about 1,350℃.The WQ-MSWIBA,with chemical composition akin to that of cement clinker,is mainly in the glass state with quartz as its main crystal phase.Its crystallinity is less than that of MSWIBA,and the leaching amount of toxic substances meets the national standard,so it can be used as admixture.(2)WQ-MSWIBA powder has a certain hydraulic hardness,but plays relatively slowly,and is affected by the alkali content and maintenance mode.(3)The cube of WQ-MSWIBA powder concrete shows ascending compressive strength,split tensile strength and elastic modulus with the increase of the powder surface area,while the surface area of concrete test cube compressive strength,split tensile strength and elastic modulus also decrease with the increase of the mixing rate.The splitting tensile strength and elastic modulus is positively correlated with the cubic compressive strength.(4)With the gradual incorporation of WQ-MSWIBA powder,the porosity of concrete gradually increases,and the aperture distribution is affected by the mixing rate and the specific surface area of the powder,and changes from small holes to large holes little by little.The average microhardness of cement stone is lower than that of ordinary concrete while ITZ is generally higher than that of ordinary concrete.The specific surface area of850 m~2/kg is conducive to improving the bonding effect of aggregate and cement stone.(5)It can be seen from the grey correlation analysis that the order of the influejce pf different pore sizes on the macroscopic mechanical properties of WQ-MSWIBA powder concrete is harmless holes>Irreducible water saturation>less harmful holes>porosity>poly harmful holes>harmful holes. |
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