中膨胀土CMA改性室内试验研究

CMA是一种新型膨胀土生态改性剂，依托合(肥)－六(安)－叶(集)高速公路工程，对CMA改性后中膨胀土的基本物理性质、击实特性、胀缩特性、力学特性等进行了3种配方的室内对比试验研究。结果表明，中膨胀土经CMA改性后，其自由膨胀率由改性前的71 %下降到20 %左右，液限和塑性指数也显著降低，亲水能力大幅度下降；胶粒含量明显下降，粉粒含量增加，说明改性后粒度组成已接近粉土；各项胀缩性指标较改性前也有大幅度下降，无荷膨胀率约为改性前的2 %，膨胀力约为改性前的5 %；改性土的CBR值可达50 %，浸水变形不到1 %；在非饱水和饱水状态下，改性土都具有较高的抗剪强度和无侧限抗压强度，说明改性后其水稳定性较好。经对比分析，认为1#配方改性效果最好，较适用于合肥膨胀土的改性处理。

Laboratory test study on CMA-treated expansive soils

As a kind of new ecological modifier, CMA has good application prospect. Based on Hefei-Luan-Yeji Expressway Project, laboratory comparative tests on basic physical, compacted, swelling-shrinkage and mechanical characteristics of CMA-treated expansive soils have been carried out. Compared with unmodified sample, the free swelling ratio of the modified samples lowers from 71% to about 20 %; its liquid limit and plastic index also decrease obviously; hydrophilic nature falls down by a wide range as well as micelle content, but silt content increases sharply. The results also indicate that index for swelling-shrinkage property has reduced, swelling ratio without load is 2 %- 3 % and swelling power is 5 % of those without modifying. The value of CBR reaches 50 % and deformation is small when soaked; soils have a high shear strength and unconfined compressive strength whether saturated or not, and possess better water stability. Conclusion can be drawn that CMA can change the properties of expansive soils notably and the first formula is suitable for Hefei expansive soils for its good treating effect.