阳离子改性剂改良膨胀土试验研究

Experimental study on expansive soil improved with cation modifier

膨胀土化学改性是化学岩土工程中的一项重要课题,受到广大岩土工程师的重视。结合云南某高速公路路堤工程,采用一种阳离子改性剂对膨胀土进行化学改良试验,探讨了改性剂的改性机理和效果。结果表明:改性剂可以彻底改变膨胀土的亲水性、胀缩性,降低自由膨胀率,大大改善膨胀土的颗粒级配、强度特性、水理特性等物理力学性质。改性后的膨胀土黏粒减少,粉粒增多,孔隙明显减少,结构更加致密,改性剂的"团聚"、"凝胶"效果显著。改性后的膨胀土干密度随含水率变化较小,水稳性提高,可以满足设计施工要求,降低了工程造价,可见该改性剂对膨胀土的工程性质有很大程度的改善。

The improvement of expansive soil with chemical medicine is an important topic in chemical-geotechnical engineering, so it has been concerned by geotechnical engineers. For the embankment engineering on an express highway in Yunnan Province, the expansive soil is improved with the cation modifier. The mechanism and the effectiveness of the improved expansive soil are discussed. It is discovered that hydrophilic nature and swelling-shrinkage property are changed drastically, that the free swelling ratio can be reduced, and that the particle size gradation, strength characteristics and hydrated properties of the treated expansive soil are improved by a wide range. Clay content decreases, but silt content increases. Pore decreases sharply, but the fabric is compact. The effectiveness of improving medicine reunited and cemented is obviously. The change of dry density with water content decreases and the hydrated property of modified soil is enhanced. The indexes are satisfied to the project and the cost is reduced. So the engineering properties of the treated expansive soil are improved to a considerable extent.