铁尾矿砂蒸压加气轻质混凝土的制备与孔隙结构研究

Study on Preparation and Pore Structure of Autoclaved Aerated Lightweight Concrete with Iron Tailings Sand

为改善因铁尾矿砂过量掺入而导致的蒸压加气轻质混凝土宏观孔隙结构劣化问题,研究发气剂(铝粉)掺量、发气剂与稳泡剂(羟丙基甲基纤维素)质量比对铁尾矿砂蒸压加气轻质混凝土宏观孔隙结构的调节作用,以及对试样抗压强度、体积密度、导热性能的影响。结果表明,在发气剂和稳泡剂质量比为1∶5的情况下,发气剂掺量为0.09%时,铁尾矿砂蒸压加气轻质混凝土具有适中的抗压强度与体积密度,接近《蒸压加气混凝土砌块》(GB/T 11968—2020)规定的强度等级A2.5、体积密度等级B05的要求。在此基础上,进一步提高稳泡剂掺量至发气剂和稳泡剂质量比为1∶7可以有效提高小微孔隙(孔隙面积≤0.5mm^(2))占比,改善孔隙均匀性,降低孔隙联通率,使铁尾矿砂蒸压加气轻质混凝土单位体积密度下所能承受的压力提高5.19%,导热系数降低6.8%,具备更为优良的抗压及隔热性能。

In order to improve the macroscopic pore structure deterioration of autoclaved aerated lightweight concrete caused by the excessive admixture of iron tailings sand,the regulating effects of the content of gas-foaming agent(aluminum powder)and the mass ratio of gas-foaming agent and foam stabilizer(hydroxypropyl methyl cellulose)on the macroscopic pore structure of autoclaved aerated lightweight concrete with iron tailings sand and the effects on the compressive strength,bulk density and thermal conductivity of the specimens were studied.The results show that when the mass ratio of gas-foaming agent and foam stabilizer is 1∶5and the content of gas-foaming agent is 0.09%,the autoclaved aerated lightweight concrete with iron tailings sand has moderate compressive strength and bulk density,which is close to the requirements of strength grade A2.5and bulk density grade B05specified in autoclaved aerated concrete block(GB/T 11968—2020).On this basis,further increasing the content of foam stabilizer to the mass ratio of gas-foaming agent and foam stabilizer of 1∶7can effectively increase the proportion of tiny pores(pore area≤0.5mm^(2)),improve the uniformity of pores,reduce the interconnection rate of pores,so that the unit volume density of autoclaved aerated lightweight concrete with iron tailings sand can withstand pressure increase by 5.19%,and 6.8%lower thermal conductivity,with more excellent compressive and thermal insulation properties.