电石渣改良膨胀土试验研究

膨胀土吸水体积膨胀,失水体积收缩的特性,给工程建设带来的危害屡见不鲜。因此如何改良膨胀土,显得尤为突出。化学改良法是膨胀土改良的常用手段之一。电石渣是工业制乙炔的主要废弃物,其堆放不仅占用大量土地,而且会造成环境及地下水污染等。通过系统的室内试验,探讨利用电石渣改良膨胀土的方法,掌握电石渣改良膨胀土的物理、力学性质及胀缩性特征。试验结果表明:随电石渣掺量的增大,改良土的最优含水率逐渐增大,最大干密度逐渐降低;塑性指数随电石渣掺量的增大先增大后降低;改良土的自由膨胀率、膨胀量、膨胀力与线缩率均随着养护龄期的增长呈减小趋势;随养护龄期的增长,改良土的压缩模量呈增大趋势,压缩系数呈减小趋势;改良土的抗剪强度随养护龄期增长主要体现在黏聚力、内摩擦角及无侧限抗压强度均随养护龄期的增长而增大;通过试验得到电石渣改良膨胀土的最优掺量为10%。扫描电镜的结果也验证了随养护龄期的增长,改良土的强度增大,胀缩性减弱。

EXPERIMENTAL STUDY OF EXPANSIVE SOIL TREATED WITH CARBIDE SLAG

The hazards caused by the swelling and shrinkage due to the changing water content of expansive soil are common occurrences. Therefore it is of great importance to investigate the improvement of expansive soil. The chemical improving process is one of the common methods. Carbide slag is the main waste of producing acetylene industrially. Stacking the carbide slag is both land-consuming and pollution. This paper investigated the expansive soil improved with carbide slag through indoor experiments. The effect of carbide slag on the physics and mechanics characteristics was evaluated as well as the swell-shrink characteristics of expansive soil. The results indicated that the optimum moisture content increased and the maximum dry density decreased with the increase of carbide slag content. The plastic index of expansive soil increased at first and then decreased with the increase of carbide slag content; the free swelling ratio and the swell capacity and the swelling pressure and the linear shrinkage ratio were decreased with the increase of curing time. The compression modulus was increased with curing time,while the coefficient of compressibility on the contrary; the increasing of shear strength with curing time was largely reflected in the increasing of cohesive force,internal friction angle and unconfined compressive strength with curing time; the 10% carbide slag was the optimum mixing proportions. The scaning result by SEM verified that the strength of the soil increased with curing time,and the swell-shrink characteristics decreased with curing time.