高掺量磷石膏稳定红黏土胀缩特性  

Swelling and shrinkage characteristics of high content phosphogypsum stabilized red clay

作　　者：陈开圣[1] 骆弟普 胡兴[1] CHEN Kaisheng;LUO Dipu;HU Xing(College of Civil Engineering,Guizhou University,Guiyang 550025,Guizhou,China)

机构地区：[1]贵州大学土木工程学院,贵州贵阳550025

出　　处：《建筑科学与工程学报》2023年第2期150-159,共10页Journal of Architecture and Civil Engineering

基　　金：贵州省科技支撑计划项目(黔科合支撑[2020]4Y038,黔科合基础-ZK[2023]重点016)。

摘　　要：为研究高掺量磷石膏稳定红黏土胀缩变形特性,改变以往磷石膏和水泥作为外掺固化剂改良土的研究思路,把磷石膏和红黏土作为主要原材料,以水泥含量5%,磷石膏和红黏土比例1∶1、1∶2、1∶3的配比制作试样,研究不同含水率、不同压实度下素红黏土和磷石膏稳定红黏土胀缩变形特性。结果表明:素红黏土绝对膨胀率在0~3 h线性增加,3 h后基本达到稳定;磷石膏稳定红黏土绝对膨胀率在0~3 h缓慢增加,变形量小于素红黏土,3 h后变形量持续增加,在2 d左右超过素红黏土,表现出更大的膨胀性,膨胀稳定时间为10 d左右;磷石膏水泥稳定红黏土混合料绝对膨胀率相较于素红黏土膨胀变形具有滞后作用,磷石膏和水泥的掺入可以有效降低混合料前期的膨胀变形,且同一含水率条件下,磷石膏掺量越低,绝对膨胀率越大;磷石膏稳定红黏土初始含水率越低,绝对膨胀率越大;磷石膏稳定红黏土和素红黏土线缩率随含水率、压实度的增大而增大;水平收缩率随含水率的增大而增大,随压实度的增大而减小;相同含水率和压实度下,磷石膏水泥稳定红黏土线缩率大于素红黏土,水平收缩率小于素红黏土;高掺量磷石膏稳定红黏土7 d龄期无侧限抗压强度能够满足规范对二级及以下公路底基层水泥稳定材料强度的要求,但其膨胀变形较大,且稳定时间较长;建议在磷石膏水泥稳定红黏土中掺外加剂进一步研究以减小其膨胀变形。In order to study the swelling and shrinkage deformation characteristics of high content phosphogypsum stabilized red clay,changing the previous research idea of using phosphogypsum and cement as external stabilizer to improve soil,phosphogypsum and red clay were used as main raw materials,the specimens with the cement content of 5%and the ratio of phosphogypsum to red clay 1∶1,1∶2 and 1∶3 were made.The swelling and shrinkage deformation characteristics of plain red clay and phosphogypsum stabilized red clay under different water content and compaction degree were carried out.The results show that the absolute expansion rate of plain red clay increases linearly in 0-3 h,and reaches stable after 3 h.The absolute expansion rate of phosphogypsum stabilized red clay slowly increases in 0-3 h,and the deformation is less than that of plain red clay.After 3 h,the deformation of phosphogypsum stabilized red clay continues to increase,and exceeds that of plain red clay in about 2 d,showing greater expansibility,and the expansion stability time is about 10 d.The absolute expansion rate of phosphogypsum cement-stabilized red clay mixture has a lag effect compared with the expansion deformation of plain red clay.The addition of phosphogypsum and cement can effectively reduce the expansion deformation of the mixture in the early stage,and under the same water content,the lower the content of phosphogypsum,the greater the absolute expansion rate.The lower the initial water content of phosphogypsum stabilized red clay,the greater the absolute expansion rate.The linear shrinkage of phosphogypsum stabilized red clay and plain red clay increases with the increase of water content and compaction degree.The horizontal shrinkage increases with the increase of water content and decreases with the increase of compaction degree.At the same moisture content and compaction,the linear shrinkage of phosphogypsum cement stabilized red clay is greater than that of plain red clay,and the horizontal shrinkage is less than that of plain re

关 键 词：改良土 磷石膏 水泥 红黏土 胀缩特性 

分 类 号：TU446[建筑科学—岩土工程]