纳米SiO_(2)/VAE胶粉复合改性水泥基材料的力学性能及抗裂性能

Mechanical properties and crack resistance of cement-based materials with nano SiO_(2)/VAE powder composite modification

利用力学性能试验、收缩试验、平板约束试验、XRD、SEM及EDS分析,研究了单掺醋酸乙烯酯-乙烯(VAE)共聚乳胶粉或复掺VAE胶粉和纳米SiO_(2)(NS)对水泥基材料力学性能及抗裂性能的影响。结果表明,复掺VAE/NS改善了由单掺VAE引起的水泥基材料早期强度降低的问题。单掺VAE或复掺VAE/NS均可降低水泥基材料的干燥收缩率和自收缩率,提高材料轴向拉伸性能,减少裂缝产生。单掺VAE可增加水泥基材料水化产物中的Ca(OH)_(2)量,而复掺VAE/NS则使Ca(OH)_(2)量有所减少,同时进一步增强水化产物之间的黏结性,降低水化产物钙硅比,优化材料微观结构,从而提高水泥基材料的力学性能及抗裂性能。

The effects of single-doped vinyl acetate-ethylene(VAE)copolymer powder and co-doped VAE/nano-SiO_(2)(NS)on the mechanical properties and crack resistance of cement-based materials were investigated by mechanical property tests,shrinkage tests,plate restriction tests,XRD and SEM-EDS.The results show that the co-doped VAE/NS can significantly improve the early strength degradation caused by single-doped VAE.Both single-doped VAE and co-doped VAE/NS can reduce the drying shrinkage and autogenous shrinkage,improve the axial tensile properties,and suppress the crack generation.The amount of Ca(OH)_(2)is increased by single-doped VAE,while the co-doped VAE/NS can reduce the amount of Ca(OH)_(2),further enhance the bond between hydration products,reduce the Ca/Si ratio,optimize the microstructure,and thus improve the mechanical properties and crack resistance of cement-based materials.