碱渣-粉煤灰基地聚合物固化软黏土的强度及渗透性研究  

Study on strength and permeability of soft clay stabilized by fly ash based geopolymer with soda residue

作　　者：陈忠清 高彦斌[2] 吕越 吴早生 魏威 CHEN Zhong-qing;GAO Yan-bin;LV Yue;WU Zao-sheng;WEI Wei(School of Civil Engineering,Shaoxing University,Shaoxing 312099,Zhejiang,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Huahui Engineering Design Group Co.,Ltd.,Shaoxing 312000,Zhejiang,China;Zhongyan Technology Co.,Ltd.,Beijing 100041,China)

机构地区：[1]绍兴文理学院土木工程学院,浙江绍兴312099 [2]同济大学地下建筑与工程系,上海200092 [3]华汇工程设计集团股份有限公司,浙江绍兴312000 [4]北京中岩大地科技股份有限公司,北京100041

出　　处：《地基处理》2024年第2期134-145,共12页Journal of Ground Improvement

基　　金：浙江省自然科学基金(LY22D020001);中国博士后科学基金(2021M702372);国家自然科学基金(41972273)。

摘　　要：“双碳”背景下寻找低碳环保的固化剂替代水泥等传统固化剂进行软土地基加固受到越来越多的关注。利用碱渣(SR)和粉煤灰(FA)制备碱渣-粉煤灰基地聚合物(SR-FAG),通过无侧限抗压强度试验(UCST)和渗透试验(PT),以及扫描电镜(SEM)试验、X射线衍射(XRD)分析与傅里叶变换红外光谱(FTIR)测试开展了SR-FAG固化含水率超液限软黏土的试验研究,分析了SR掺量、FA掺量及养护龄期对SR-FAG固化土无侧限抗压强度及渗透性的影响,并探讨了固化机理。研究表明:SR掺量对SR-FAG固化土的早期强度增长作用较明显,7 d的强度可达到28 d的56%~89%,而后期强度增长主要受FA掺量影响。当SR掺量为30%且FA掺量达到25%时,SR-FAG固化土28 d的强度可达到1.6 MPa,并随龄期持续增长。SR-FAG固化土90 d龄期的渗透系数比固化前降低近一个数量级,达到1.344×10^(-8)cm/s。C-S-H凝胶充填固化土中土颗(团)粒的大孔隙,并发挥胶结作用,导致SR-FAG固化土的早期强度增长与渗透性降低,而后期强度增长则与硅铝酸盐凝胶的胶结作用密切相关。The increasing emphasis on developing environmentally friendly cementitious binders with low carbon footprints to replace traditional binders such as ordinary Portland cement for stabilizing soft soil is particularly significant under the background of“double carbon”.In this study,a geopolymer known as fly ash(FA)based geopolymer with soda residue(SR-FAG)was formulated to stabilize soft clay with water content exceeding the liquid limit.Various tests,including unconfined compression strength test(UCST),permeability test(PT),scanning electron microscope test(SEM),X-ray diffraction(XRD)analysis,and Fourier transform infrared reflection spectrum(FTIR)analysis,were conducted.These tests aimed to examine the influence of SR content,FA content,and curing time on the unconfined compression strength(UCS)and permeability of SR-FAG stabilized soil,while also discussing the underlying improvement mechanism.The results indicate that the SR content significantly affects the early strength development of SR-FAG stabilized soil.At 7 days of curing,the UCS can reach 56%to 89%of the UCS at 28 days of curing,with late strength development primarily influenced by the content of fly ash(FA).Specifically,at an SR content of 30%and an FA content of 25%,the UCS of SR-FAG stabilized soil at 28 days of curing can reach 1.6 MPa,with a continuous increase observed with curing time.Additionally,the permeability coefficient decreases by nearly an order of magnitude after 90 days of curing,reducing to 1.344×10^(-8) cm/s from its initial value before stabilization.The mechanism underlying these improvements involves C-S-H gels filling the macropores and cementing the soil particles(aggregates),promoting early strength development and reducing permeability in SR-FAG stabilized soil.Late-stage strength growth is closely associated with the cementation of aluminosilicate gels.

关 键 词：软黏土 粉煤灰基地聚合物 碱渣 固化 无侧限抗压强度 渗透性 

分 类 号：TU472[建筑科学—结构工程]