纤维增韧地质聚合物改良膨胀土力学特性试验

Experiments on mechanical properties of fiber reinforced geopolymer for expansive soil improvement

针对膨胀土对工程建设的危害,提出一种纤维加筋和化学改良相结合的技术,开展无侧限抗压强度试验,探讨固化剂类型和掺量、碱激发剂的掺入、玄武岩纤维掺量以及养护龄期对改良膨胀土无侧限抗压强度的影响。研究结果表明:双掺矿渣微粉粉煤灰(GGBSFA)的改良效果优于单掺,GGBSFA的最优掺量为20%,并且掺入碱激发剂Na2SiO3的改良效果较好,碱激发GGBSFA改良土的强度比GGBSFA改良土的提高了107%;随着纤维掺量的增加,改良土的强度呈现先增大后减小的趋势,GGBSFA改良土的纤维最优掺筋率为0.6%;改良土的强度随着养护龄期的延长逐渐提高。龄期越长,改良土的脆性越大,韧性越差。

Considering the expansive soil damage in the construction engineering, a technology based on fiber reinforcement and chemical modification was proposed. The unconfined compression tests were carried out to investigate the strength of expansive soil under different influencing factors of type and content of the solidifying agent, blending ratio of alkali activator and basalt fiber and curing time of the samples. Results showed that the mixing of ground granulated blast furnace slag (GGBS) and fly ash (FA) was better for the strength improvement of expansive soil. 20% of GGBS-FA mixture was the optimum blending ratio. Adding Na2SiO3 in GGBS-FA modified soil could further improve the strength, which was 107% higher than that of the soil without any alkali activator. The strength of the modified soil increased to the max and then decreased with the increase of fiber content. The optimum reinforcement content of GGBS-FA modified soil was 0.6%.The strength of the modified soil increased gradually with the curing time. The longer the age, the greater the brittleness and the worse toughness of the modified soil.