为制备低成本、防火、保温隔热性能优异的无机保温隔热材料,以复合促凝剂改性的普通硅酸盐水泥为胶凝材料,采用物理法制备了超轻泡沫混凝土(孔隙率＞90％),结合图像分析、SEM及 XRD对硬化试样的气孔结构及组成进行了表征,并研究了复合促凝剂对新拌超轻泡沫混凝土工作性、硬化超轻泡沫混凝土气孔结构、抗压强度及导热系数的影响.研究表明,复合促凝剂掺量增加,新拌超轻泡沫混凝土相对粘度与相对极限剪切应力变大,流动度减小,硬化试样中小于0．2 mm 气孔比例增加,D50变小,气孔孔径均匀程度与保温隔热性能改善,力学性能先提升后略有降低；复合促凝剂掺量为4％,硬化试样的干密度为175．2 kg/m3,7D、28D 抗压强度分别为0．25和0．33 MPa,导热系数为0．0516 W/(m·K).
Motivated by the requirement for low cost,fire resistant,inorganic thermal insulation materials with high performance,ultra-lightweight foamed concretes (porosity>90%)were prepared by introducing pre-formed foam into Portland cement slurries containing different dosages of composite set-accelerator,air-voids structure and the composition of foamed concrete were analyzed by SEM,XRD,and image analysis,and the workability of fresh foamed concrete,compressive strength,thermal conductivity and air-void structure of harden foamed concrete were studied.The results indicate that the relative plastic viscosity and the relative yield stress of fresh foamed concrete increase with the dosage of set-accelerator,and the slump flow reduces.With the increase of set-accelerator,the amount of small air-voids (<0.2 mm)increases,D50 reduces and pore size distribution becomes uniform significantly,which improve the thermal insulating property,the mechanical property improves at first,and then becomes poor slightly.With 4% of set-accelerator,the apparent density is 175.2 kg/m3 ,the compressive strength at 7 days and 28 days achieves 0.25 MPa and 0.33 MPa,and the thermal conductivity is 0.0516 W/(m·K).
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