纳米SiC复配PVA对矿用水泥基封孔材料早强性能的影响

Effect of Nano-SiC Compounded with PVA on Early Strength of Mining Cement-Based Sealing Material

为改善水泥基封孔材料在煤矿工作环境中存在的早期强度低、自收缩、流失率高等缺陷,以水泥为基础添加纳米SiC同时复配高分子材料聚乙烯醇(PVA),通过抗压强度、流动度、凝结时间、XRD、电镜扫描(SEM)、热重(TG-DTG)等力学性能测试和微观结构分析,研究纳米SiC复配PVA对水泥基封孔材料性能的影响。试验结论:当添加纳米SiC质量比为0.3%,PVA质量比为0.2%时,对水泥样品早期强度有较为明显的提升,其1 d、3 d、7 d、28 d的抗压强度分别达到15.441 MPa、26.091 MPa、34.273 MPa、48.673 MPa,相较于同龄期空白组分别提升了115.45%、50.33%、24.39%、39.89%,且终初凝时间明显缩短。根据微观结构分析,添加纳米SiC和PVA的试验组内部更为紧密均匀,纳米SiC填补了试样内部空隙,降低了孔隙率,同时二者形成互相穿插的膜状结构,改善了水泥内部构造;高分子膜能够提高水泥的抗压、抗拉性能,带来更为优异的结构强度。

In order to improve the problems of low early strength, self-shrinkage and high loss rate of cement-based sealing materials in the working environment of coal mines, nano-SiC was added on the basis of cement and polymer material polyvinyl alcohol(PVA) was compounded at the same time. The effects of nano-SiC compounded with PVA on the properties of cement-based sealing materials were studied through mechanical tests and microstructure analysis such as compressive strength, fluidity, setting time, XRD, SEM and TG-DTG. Test conclusions are as follows. When the mass ratio of SiC is 0.3% and the mass ratio of PVA is 0.2%, the early strength of cement sample is significantly improved. The compressive strength of cement sample at 1 d, 3 d, 7 d and 28 d is 15.441 MPa, 26.091 MPa, 34.273 MPa and 48.673 MPa, respectively, which are increased by 115.45%, 50.33%, 24.39%, 39.89% comparingwith the blank group at the same age, and the initial and the final coagulation time is significantly shortened. According to the microscopic analysis, the internal structure of the test group of nano-SiC compounded with PVA is more compact and uniform. Nano-SiC can fill the internal voids of the sample and reduce the porosity. At the same time, the two formed a membrane structure interspersed with each other, which would improve the internal structure of cement. The polymer membrane could improve the compressive and tensile properties of cement and bring more excellent structural strength.