木质素改良粉土基本工程特性试验研究

将工业副产品木质素应用于粉土改良.通过界限含水率、颗分、击实、无侧限抗压强度和电阻率等室内试验,对素土及掺木质素改良土的基本物理力学性质、p H值和电学特性等进行对比研究,明确改良土的基本工程特性变化规律和改良效果,并采用扫描电子显微镜(SEM)对土体微观结构变化进行对比分析,阐述了木质素与土体的相互作用机理.试验结果表明:木质素可有效改善粉土的颗粒级配,降低土体的塑性指数;改良后粉土的最大干密度增加,最佳含水率减小,同时干密度对含水率变化的敏感性增强;改良土的无侧限抗压强度优于素土,p H值低于10,龄期和含水率对强度影响显著,对p H值无明显影响;胶结物质填充孔隙并联结土颗粒,改良土微观结构更为稳定.这说明木质素可有效改善粉土的基本工程特性.

Experimental Study on Basic Engineering Properties of Silt Improved by Lignin

The lignin， an industrial by-product， is utilized to improve the silt. A series of laboratory tests on moisture content， particle size distribution， compaction， unconfined compression strength and electrical resistivity are carried out to study the mechanical and physical properties of natural silt and lignin-improved silt. The pH value and electrical characteristics of improved soil are also investigated. Scanning electron microscopy (SEM) is used to analyze the variations of soils microstructure， and the stabilization mechanism of lignin-treated silt is preliminarily discussed. The results indicate that lignin can effectively improve the particle size distribution and reduce the plastic index of soil. As to improved silt， maximum dry density increases， the optimum moisture content decreases， while the change of dry density with moisture content is enhanced. The lignin-treated silt has greater strength performance than the natural silt in terms of unconfined compression strength and all the improved soils have a pH value lower than 10. Curing time and moisture content have a significant impact on unconfined compression strength， but little effect on pH value. The pores of soils are filled and particles are connected with cementing material， then a more stable soil structure was formed. It is shown that adding lignin can successfully improve the basic engineering properties of silt.