Study On Preparation And Properties Of Granite Powder Aerated Block

This article adopted high temperature and high pressure steaming technology,used fine grinding granite stone powder as the main raw material,and lime,gypsum,cement,air-entraining agent,foaming agent and so on as the auxiliary materials,By studying and adjusting process conditions and ratio of raw materials,the effects of raw materials and experimental conditions on performance of aerated concrete blocks were obtained.Preparation of a set of lightweight,heat insulation,resistance to shrinkage,fire prevention,and the advantages of convenient construction and meeting the national standard of heat preservation heat preservation material-autoclaved aerated concrete block.The effect of autoclave time and pressure on dry density and compressive strength is greater than that of stone powder fineness.With extension of autoclave time,dry density and water absorption increased first and then decreased,and compressive strength increased gradually.With increase of autoclave pressure,dry density and water absorption decreased first and then increased,while compressive strength first increased and then decreased.The optimal autoclave pressure time is 8h,the autoclave pressure is 1.0MPa,the fineness of tone powder is 523 m2/kg.With the increase of water cement ratio and aluminum powder paste content,both dry density and compressive strength of block were reduced,and water absorption rate increased.With increase of cement content,compressive strength increased,but the excessive content of cement is not obvious to the improvement of strength.The aerated concrete block with better ratio was obtained,its dry density was 622Kg/m3,water absorption rate was 59.5%,and compressive strength was 4.2MPa,which reached the standard requirement of grade B06.Adjusted water cement ratio,aluminum powder paste content and cement content,and got the aerated concrete block with optimized proportioning which the dry density was 684kg/m3,water absorption was 55.2%,compressive strength was 5.4MPa,reached the standard requirement of grade B07.The single factor experiment was carried out to obtain the effect of air entraining agent content,lime content and gypsum content on the performance of block.The optimum dosage was determined: water cement ratio 0.475,aluminum powder paste 0.1wt%,cement content 21wt%,granite powder content 59wt%,air entraining agent content 0.1%,lime content 12%,gypsum content 5%,dry density of block was 818 kg/m3,absorption rate was 48.5%,compressive strength was 8.6MPa,standard requirements of B08 grade aerated blocks.Based on the linear fitting equation of thermal conductivity and dry density,the thermal conductivity of B06,B07 and B08 grade aerated concrete blocks with optimum ratio were 0.16,0.17,and 0.20 W/(m.K).The types,structure and morphology characteristics of hydration products of granite powder aerated block were studied by XRD and SEM techniques,The main hydration products are various forms of tobermorite,CSH gel,calcium silicate hydrate,and unreacted quartz particles.The macroscopic holes in blocks are mutually independent and mutually closed holes,and the pore diameter is about 1.5-3mm.The micro pores are formed by the cross connection of the hydration products,and the pore diameter is about 1?m to 3 ?m.