Research On Properties Of Areated Concrete For Self-insulation Wall In Cold Regions

According to the building energy conservation demand of65%in cold region,this paper studies the effect of preparation parameters on the properties of B05levelaerated concrete systematically. This paper focuses on the influence factors on thecompressive strength of air entrained concrete as well as the technical measures forthe decrease of aerated concrete water absorption.Firstly, the preparation parameters of aerated concrete in the laboratory aredetermined, including mixing time, curing conditions, temperature and time ofautoclave curing, to obtain high quality aerated concrete block. Meanwhile, theeffect of quicklime hydration problems and water content on molding of aeratedconcrete block has been studied.Through orthogonal design of fly ash, cement and aluminum consumption, thebasic mix proportion of B05aerated concrete is determined as fly ash: cement: lime:gypsum=69:12:15:4. Moreover, water to feed ratio, water reducing agent dosageisand aluminum content dosage are0.53,1‰of total materialand,0.56%of limeand cement, respectively. The optimal content of ferrosilicon alloy powders isconfirmed as1/4of aluminum powder by analyzing the compressive strength andpore structure of aerated concrete for the corresponding optimum pore structure.When the content of calcium chloride is0.25%at cement mass, the compressivestrength of aerated concrete was significantly improved. Dry density and thecompressive strength of aerated concrete can reach518kg/m3and3.6MPa byincorporating polypropylene fiber with0.1%of cementing materialby mass.Secondly, the high water absorption of aerated concrete is harmful, unfavorablefor its thermal construction, insulation and frost resistance.The water absorption testresults indicate that the silicone-based water repellent agent is found to improve thefluidity of aerated concrete paste, to deteriorate its pore structure and to reducewater absorption rate of aerated concrete base rather than that of aerated concreteblock. Besides, adding calcium stearate will reduce the water absorption as well asfluidity of aerated concrete. When the content of calcium stearate is up to3.0%, thewater absorption rate of concrete is35.8%.Finally, the relationship between water absorption and frost resistance ofaerated concrete is verified. Aerated concrete with large water absorption and lowcompressive strength has poor frost resistance. With the incorporation ofhydrophobic agent, the strength of aerated concrete decreases slightly. The frostresistance of aerated concrete is improved after adding the calcium stearate.