磷石膏稳定红黏土的压缩特性及微观机理

摘要/Abstract

摘要： 针对红黏土特殊工程性质以及磷石膏固废资源的浪费现象,通过固结试验,以水泥为固化剂,研究不同配合比下磷石膏稳定红黏土的压缩特性,并基于微观结构和矿物组成分析压缩模量变化的机理。结果表明,素红黏土为中压缩性,磷石膏稳定红黏土为中、低压缩性。混合料压缩模量随磷石膏掺量增加先增大后减小,水泥与磷石膏质量比为1：3时压缩模量最大。各因素对混合料压缩模量的影响程度依次为竖向荷载>水泥掺量>磷石膏掺量。混合料压缩模量与水泥掺量、磷石膏掺量可通过二元三次函数关系拟合。随着磷石膏掺量增加,水泥的水化反应、吸附作用以及钙矾石的生成使混合料孔隙率降低,当水泥与磷石膏质量比为1：3时,孔隙率最小。当磷石膏掺量继续增大,溶液呈酸性,钙矾石溶解,游离氧化铁减少,团聚体内的胶结作用与咬合作用降低,压缩模量减小。

关键词: 磷石膏, 红黏土, 水泥, 压缩特性, 压缩模量, 微观机理

Abstract: In view of special engineering properties of red clay and the waste of phosphogypsum solid-waste resource, the compression characteristics of phosphogypsum-stabilized red clay under different mixing ratios were studied through consolidation tests with cement as curing agent. And the mechanism of compressive modulus change law was analyzed based on microstructure and mineral composition. The results show that plain red clay presents medium compressibility, while phosphogypsum-stabilized red clay presents medium and low compressibility. The compressive modulus of mixture increases first and then decreases with the increase of phosphogypsum content. The compressive modulus is the largest as the mass ratio of cement to phosphogypsum is 1：3. The degree of influence on the compressive modulus of mixture is vertical load>cement content>phosphogypsum content. The compressive modulus of mixture can be fitted by a binary cubic function relationship with cement content and phosphogypsum content. With the increase of phosphogypsum content, the hydration reaction, adsorption of cement and the formation of ettringite reduce the porosity of the mixture. When the mass ratio of cement to phosphogypsum is 1：3, the porosity is minimum. When the content of phosphogypsum continues to increase, the solution is acidic, ettringite is dissolved, the content of free iron oxide decreases, the cementation and mechanical bite of aggregates are reduced, and the compression modulus is reduced.

Key words: phosphogypsum, red clay, cement, compression characteristic, compressive modulus, microscopic mechanism

中图分类号:

TU446

罗国夫, 陈开圣, 骆弟普. 磷石膏稳定红黏土的压缩特性及微观机理[J]. 硅酸盐通报, 2023, 42(2): 644-656.

LUO Guofu, CHEN Kaisheng, LUO Dipu. Compression Characteristics and Microscopic Mechanism of Phosphogypsum-Stabilized Red Clay[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(2): 644-656.

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