阳离子型化合物改良膨胀土试验研究

为探究不同阳离子化合物改良膨胀土工程特性的实际效果,并确定最佳复合配比,分别选用硅酸钠(Na₂SiO₃)和阳离子聚丙烯酰胺(CPAM)作为改良剂,对改良土样进行一系列物理力学性能研究。结果表明:随着两种改良剂的掺入,膨胀土的液塑限、胀缩率、强度均有明显改善与提高;界限含水率指标上,两种改良剂改善效果相差不大;CPAM更有效降低土的膨胀性;Na₂SiO₃在降低土的收缩性和提高抗剪强度方面效果更明显。选用0.6% CPAM与Na₂SiO₃进行复掺,随着Na₂SiO₃掺量的增加,改良土的无侧限抗压强度呈现先增长后降低的趋势,4% Na₂SiO₃和0.6% CPAM复掺效果最佳且水稳性更优,扫描电镜(SEM)显示复掺改良后膨胀土由弯曲起皱片状结构转为块状结构,提高了土体的密实性和强度。

Experimental Study on the Improvement of Expansive Soil with Cationic Compound

In order to explore the actual effects of different cationic compounds on improving the engineering properties of expansive soils and determine the best composite ratio, sodium silicate (Na₂SiO₃) and cationic polyacrylamide (CPAM) were selected as modifiers, and a series of physical and mechanical properties studies were conducted on the soil samples before and after the improvement. The results show that with the addition of the two modifiers, the liquid-plastic limit, expansion and shrinkage rate and strength of expansive soil have been significantly improved and increased. In terms of the boundary water content index, the improvement effects of the two modifiers are not much different; CPAM can reduce the swelling property of soil more effectively. The effect of Na₂SiO₃ in reducing soil shrinkage and improving shear strength is more obvious. The mixture of 0.6%CPAM and Na₂SiO₃ was selected. With the increase of Na₂SiO₃, the unconfined compressive strength of improved soil exhibits a trend of first increasing and then decreasing. The compound mixing effect of 4% Na₂SiO₃ and 0.6% CPAM is the best and the water stability is better. Scanning electron microscopy (SEM) shows that the modified expansive soil has changed from a curved and wrinkled flake structure to a blocky structure, which improves the compactness and strength of the soil.