干湿循环作用下钢渣-偏高岭土改性膨胀土工程性质试验研究

文章以钢渣-偏高岭土改性膨胀土为研究对象, 通过一系列的室内试验分析干湿循环作用对改性土工程性质的影响。研究结果表明: 干湿循环作用下, 改性土的强度远高于素土的强度, 其压缩系数、膨胀指标低于素土, 在前5次干湿循环内, 改性土强度下降、压缩系数上升趋缓; 继续增加干湿循环次数, 改性土强度显著下降、压缩系数上升速度加快, 但其强度仍满足二级公路基层建设要求; 在干湿循环11次后, 干湿循环作用对改性土工程性质影响减弱。微观结构分析表明: 钢渣-偏高岭土改性剂可以在膨胀土内生成水化产物; 在经历干湿循环作用后, 水化产物的结构发生破坏, 土颗粒间胶结力下降, 土体内大孔增多、微裂隙发生扩张, 这些是导致改性土工程性质劣化的重要因素。

Steel slag-metakaolin modified expansive soil is taken as the research object, and the influence of wetting-drying cycles on the engineering properties of modified soil is analyzed through a series of indoor experiments. The results indicate that under wetting-drying cycles, the strength of the modified soil is significantly higher than that of the original soil, with lower compression coefficients and expansion indexes. Within the first five wetting-drying cycles, the strength of the modified soil decreases and the compression coefficient increases slowly. As the number of wetting-drying cycles continues to increase, the strength of the modified soil decreases significantly, and the rate of increase in compression coefficient accelerates. However, the strength of the modified soil still meets the requirements for the construction of secondary highway subgrades. After 11 wetting-drying cycles, the influence of wetting-drying cycles on the engineering properties of the modified soil weakens. Microscopic experiments demonstrate that the steel slag-metakaolin modifier can generate hydration products within the expansive soil; after undergoing wetting-drying cycles, the structure of hydration products is damaged, leading to a decrease in interparticle bonding strength, an increase in macropores, and expansion of microcracks within the soil body, which are important factors contributing to the deterioration of the engineering properties of the modified soil.