减水剂对物理法超轻泡沫混凝土气孔结构及性能的影响研究

Effect of Water Reducing Agent on Air-void Structure and Properties of Ultra-lightweight Foamed Concrete

以普通硅酸盐水泥为胶凝材料,辅以萘系减水剂(F)与聚羧酸减水剂(S),在水泥净浆水灰比为0.5与0.8的条件下,采用物理法制备了孔隙率大于90%的超轻泡沫混凝土,结合Image-pro plus、XRD、SEM、TG等手段对硬化超轻泡沫混凝土气孔结构及组成进行了表征,并研究了减水剂(S与F)对硬化试样力学性能及保温隔热性能的影响。研究表明:S与F可减小硬化试样的气孔孔径分布范围,改善气孔均匀程度,减水剂S较F更能促使D50的减小及气孔(<0.2mm)的比例的增加;减水剂S与F均能改善硬化试样的力学性能与保温隔热性能,当水泥净浆水灰比为0.8,掺入减水剂F的试样干密度为193.5kg/m3,28d抗压强度为0.41 MPa,导热系数为0.050 9 W/(m·K)。

Ultra-lightweight foamed concrete （porosity〉90 %） was prepared by introducing preformed foam into Port- land cement slurry with different W/C （0. 5, 0. 8） and water reducing agents （polycarboxylate superplasticizer S and sulfonated naphthalene formaldehyde F）, the air-void structure and the composition of harden sample were characterized by Image-pro plus, XRD, SEM and TG. The effect of water reducers on the mechanical property and thermal insulation performance were also discussed. The experimental results show that water reducers have positive effects on increasing the small air-voids （〈0. 2 mm）, decreasing the air-voids size distribution and achieving more uniform distribution of air- voids, with the adding of water reducer, the mechanical property and thermal insulation performance of hardened sample improve significantly. When the dry density of sample with F is 193.5 kg/m^3 and the w/c of cement slurry is 0. 8, the compressive strength 28 d achieves 0. 41 MPa, and the thermal conductivity is 0. 050 9 w/（m · K）.