纳米SiO2和丁苯胶粉复合改性水泥基材料的强度及抗渗性能

本文研究了单掺丁苯胶粉(SBR)和复掺SBR/纳米SiO₂(NS)对水泥基材料抗折强度、抗压强度、吸水率、抗氯离子渗透系数的影响规律,并采用XRD、DSC-TG、FTIR、SEM-EDS、MIP等手段对水泥基材料水化产物和微观结构进行分析,探究单掺SBR和复掺SBR/NS对水泥基材料强度及抗渗性能的影响机理。结果表明,复掺SBR/NS显著改善了由单掺SBR引起的水泥基材料早期强度下降的问题,单掺SBR和复掺SBR/NS均可降低试样的吸水率、吸水速率和非稳态氯离子迁移系数,且复掺效果优于单掺。微观测试表明:单掺SBR可降低Ca(OH)₂的含量,减少有害孔和多害孔的数量,增加结构整体性;复掺SBR/NS可进一步降低Ca(OH)₂的含量,促进水化反应生成更多C-S-H,提高C-S-H的聚合度,降低最可几孔径,减少少害孔、有害孔和多害孔的数量,降低水化产物的钙硅比,从而增强试样的抗折强度和抗压强度并提高其抗渗性能。

Strength and Impermeability of Cement-Based Materials with Nano SiO2 and Styrene-Butadiene Rubber Powder Composite Modification

In this paper, the flexural strength, compressive strength, water absorption and unsteady chloride ion migration coefficient were used to investigate the effect of styrene-butadiene rubber powder (SBR)/nano SiO₂ (NS) on strength and impermeability of cement-based materials. The hydration products and microstructure of cement-based materials were analyzed by XRD, DSC-TG, FTIR, SEM-EDS and MIP. Results show that complex SBR/NS significantly improves the early strength degradation of cement-based materials caused by single SBR. Both single SBR and complex SBR/NS reduce the water absorption, water absorption rate and unsteady chloride ion migration coefficient, and the effect of complex SBR/NS is better than that of single SBR. The microscopic test shows that the single SBR reduces the content of Ca(OH)₂ and the number of harmful pores and more-harmful pores and increases the integrity of the structure. The complex SBR/NS further reduces the content of Ca(OH)₂, promotes the hydration reaction to generate more C-S-H, improves the polymerization degree of C-S-H, decreases the most probable aperture, reduces the amount of less-harmful pores, harmful pores and more-harmful pores, lowers the Ca/Si ratio of hydration products, and thus enhances the flexural strength, and compressive strength and improves the impermeability of the sample.