Research On Preparation And Property Of Aerated Concrete With Quartz Tailings

With the rapid development of China's economy,the production and storage of industrial solid waste is increasing day by day.According to China's“Thirteen Five Year Plan”put forward to the urgent requirement to develop recycling economy,strengthening the comprehensive disposal and recycling industrial solid waste as secondary resource,promoting the development of green building materials industry has been an important task in the current situation.Quartz tailings are formed during the exploitation and utilization of siliceous mineral resources.The main chemical composition is SiO₂,which is mainly composed of fine crystalline quartz,and SiO2 content is generally between 85%⁹8%.As estimated,10 million tons quartz tailings are produced every year only from the glass industry.At present,most of quartz tailings are stockpiled in the tailings reservoir,which takes up the land and causes pollution,and also is a serious waste of the earth's mineral resources.Autoclaved aerated concrete?AAC?is a new type of energy saving wall material with excellent energy-saving performance due to its porous structure,can be well applied to modern architecture system.It not only has the advantages of light weight,heat preservation,heat insulation,sound insulation,fire resistance and other good performances,and also can absorb a great amount of industrial solid waste,so it has broad development prospects.Therefore,the application of quartz tailings in aerated concrete can greatly improve the amount of quartz tailings,effectively improve the efficiency of resource utilization and produce good economic,environmental and social benefits..In this paper,we take quartz tailings as research subjects supplied by Guangxi Binyang Lituo new building materials Co.,with lime,cement,gypsum,aluminum powder and other materials added to prepare aerated concrete.Research is mainly focused on the influence of quartz tailings grinding time and content,material matching and process parameters of aerated concrete.Besides,volume density,thermal insulation properties,microstructure and hydration products were also tested and analyzed.Studies have shown that the micro powder reactivity can be effectively improved when grinding quartz tailings 20mins.Among them,the optimal formula is:quartz tailings60%,cement 12%,lime 25%,gypsum 3%,gas former0.08%,sodium silicate 1.0%,foam stabilizing agent 1.0%.And the optimal parameters:w/s 0.65,pouring temperature 55?,static curing temperature 50?,static time 4h,autoclave curing temperature 185??1.1MPa?,constant time 8h.Under such conditions,dry density of the product is 615.4kg/m³,compressive strength can reach 5.0MPa.And the mechanical properties of B06 level aerated concrete prepared can better in line with the requirements of GB/T 11968-2006.By XRD and SEM analysis,siliceous materials and calcareous materials have undergone a series of hydrothermal synthesis under high temperature and high pressure environment in the autoclave curing process.In the process,crystallinity improves and the structure becomes more compact.In autoclave curing conditions,Ca?OH?₂ can generate chemical reaction with a large amount of SiO₂ and Al₂O₃ released by quartz tailings to produce hydration products.The main hydration products conclude:weakly crystallized C-S-H gel,a large number of needle-like,plate-like crystals of tobermorite,calcite,in addition some incomplete reaction SiO₂ particles are still left.C-S-H gel bind tobermorite crystals together,forming a good network frame structure,which improves the compressive strength of the product.