硅灰对PB-g-PS胶乳改性水泥砂浆的性能影响

Effect of silica fume on properties of PB-g-PS latex modified cement mortar

质量比为50/50的聚丁二烯接枝聚苯乙烯(PB-g-PS)胶乳用于改性水泥砂浆。考察了硅灰含量和聚灰比对改性水泥砂浆的流动度、抗压和抗折强度以及吸水量的影响。研究表明:改性砂浆的流动度随硅灰含量的增加而降低,随聚灰比增加而增加;适量的硅灰能降低改性砂浆的毛细孔吸水量,而随聚灰比的增加,改性砂浆的毛细孔吸水量降低;胶乳的加入使抗压强度降低,部分改性砂浆的抗折强度有所提高,硅灰的加入极大地改善了砂浆的力学性能,改性砂浆的抗压、抗折强度最大值分别为34.97、6.86 MPa。利用SEM观察了改性砂浆的结构,改性砂浆结构更加致密,界面结构得到改善,并观察到了带状的聚合物膜结构和六角形的片状的氢氧化钙晶体结构。综上所述,硅灰和胶乳二者可以复合改性水泥砂浆。

PB-g-PS latex with a mass ratio of 50/50 was used to modify cement mortar.Examined the effects of silica fume content and polymer-cement ratio （P/C） on properties of latex modified cement mortar.The experimental results showed that the flowability of modified mortars increased with increasing P/C, and decreased with silica fume conent.The silica fume could markedly reduce capillary water absorption rate, it reaches 0.647 kg/m2 at 24 h, and can improve the mechanical performance of mortars.The maximum of compressive and flexural strength of modified mortar were 34.97 MPa and 6.86 MPa,respectively.The modified mortar structure was studied by SEM.The microstructure analysis showed that mortar constituents in PMMs were compactly joined with each other, and the structure was close.The band-like structure of polymer film and hexagonal sheet crystal structure were seen.The structure was improved because of addition silica fume to latex modified cement mortars. The development of little crackle was effective prevented, hence, the performance of the mortar has been improved.