PVA纤维和纳米SiO2对地聚合物砂浆断裂性能的影响

Effect of PVA Fiber and Nano SiO2 on Fracture Properties of Geopolymer Mortar

摘要:

针对72个尺寸为100mm×100mm×400mm的预切口小梁试件进行三点弯曲断裂试验，以临界有效裂缝长度、起裂断裂韧度、失稳断裂韧度和断裂能等参数为评价指标，研究了纳米SiO2质量分数或聚乙烯醇（PVA）纤维体积分数对地聚合物砂浆断裂性能的影响.结果表明：在一定掺量范围内，纳米SiO2或PVA纤维的掺入可以提高地聚合物砂浆的断裂性能；PVA纤维或纳米SiO2掺入地聚合物砂浆后，能较大幅度地提高小梁试件的峰值荷载、临界有效裂缝长度、起裂断裂韧度、失稳断裂韧度和断裂能，这些断裂参数在纳米SiO2掺量或PVA纤维掺量逐渐增大时皆呈现先增大后减小的趋势，并且在PVA纤维体积分数为10%或纳米SiO2质量分数为15%的条件下达到最大值，此时小梁试件的荷载裂缝口张开位移曲线最饱满，与坐标轴之间的包络面积最大.

Abstract:

Through the three point bending fracture test of 72 pre cut girders with dimensions of 100mm×100mm×400mm, the parameters such as effective crack length, initial fracture toughness, unstable fracture toughness and fracture energy were used as evaluation indices to study the effect of nano SiO2 and PVA fiber content on the fracture properties of geopolymer mortar. The experimental results show that the incorporation of nano SiO2 and PVA fibers can improve the fracture properties of geopolymer mortar in a certain dosage range. The peak load, effective crack length, initial fracture toughness, unstable fracture toughness and fracture energy of the beam specimens of geopolymer mortar were enhanced greatly with the usage of PVA fiber and nano SiO2. These fracture parameters increase firstly and then decrease with the increment in PVA fiber and nano SiO2 content. The maximum of the fracture parameters were observed when the volume fraction of PVA fiber reaches 10% and the mass fraction of nano SiO2 reaches 15%, and the envelope area under the relation curve between the load and crack mouth opening displacement of the beam specimen exhibits the maximum.