低温养护下电石渣激发偏高岭土基地聚物固化土力学特性及固化机制研究  

Study on mechanical properties and curing mechanism of metakaolin based geopolymer solidified soil activated by calcium carbide slag under low temperature curing

作　　者：刘凤云 罗怀瑞 万旭升[1] 路建国 LIU Feng-yun;LUO Huai-rui;WAN Xu-sheng;LU Jian-guo(School of Civil Engineering and Geomatics,Southwest Petroleum University,Chengdu,Sichuan 610500,China)

机构地区：[1]西南石油大学土木工程与测绘学院,四川成都610500

出　　处：《岩土力学》2023年第11期3151-3164,共14页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.42071087);西南石油大学起航计划资助项目(No.2021QHZ003)。

摘　　要：为解决使用水泥固化冻土时热扰动大及水泥带来的碳排放等问题,采用电石渣作为碱激发剂激发偏高岭土基地聚物固化土质,研究偏高岭土掺量、电石渣掺量、养护温度和养护龄期对固化土抗压强度的影响规律,并与水泥固化土进行平行对比,采用X射线衍射和电镜扫描等试验方法进行微观分析,揭示其固化机制。试验结果表明:偏高岭土和电石渣均存在最优掺量,当掺量小于最优掺量时发挥积极作用,超过时则会产生反作用。其中偏高岭土和电石渣的最优掺量分别为10%和6%,最优掺量试样在20、-2、-10℃养护28 d的抗压强度分别为3.783、1.164、0.901 MPa。电石渣激发偏高岭土基地质聚合物主要产物有无定型的水化硅酸钙、水化铝酸钙凝胶,是固化土抗压强度提升的主要原因。地聚物固化土在-2℃和-10℃养护28 d的抗压强度相较于在20℃养护28 d分别降低69%和76%,冻结状态下土体冰晶扩张土孔隙,同时促使裂缝生长,降低地质聚合反应效率,聚合产物数量减少。试样抗压强度随养护龄期的增加而增加,地质聚合反应产生的硅铝网格结构随养护龄期的增加而增多,使土体内部结构相互交织联结,形成更加密实的结构。地质聚合反应受到低温影响较小,地聚物固化土在20、-2、-10℃养护28 d的抗压强度分别为水泥固化土的1.07、1.13和1.19倍。研究结果可为地聚物在冻土区路基土质加固的应用奠定一定的理论基础。In order to address the issues about significant thermal disruption and carbon emissions associated with the use of cement for solidifying frozen soil,calcium carbide slag was used as an alkali activator to activate metakaolin based geopolymer for soil solidification.In this research,the impacts of metakaolin and calcium carbide slag contents,curing temperature and curing age on the compressive strength of the solidified soil were investigated.Geopolymer solidified soil and cement solidified soil were compared in parallel.The curing mechanism was studied by X-ray diffraction and electron microscope scanning.Test results indicate that there is an optimal content of metakaolin and calcium carbide slag.When the content is lower than the optimal content,it plays an active role.On the contrary,it will have a negative effect.The optimal content of metakaolin and calcium carbide slag is 10% and 6%,respectively.The compressive strength of the optimal content sample cured at 20℃,-2℃ and -10℃ for 28 days is 3.783 MPa,1.164 MPa and 0.901 MPa,respectively.The main products of metakaolin based geopolymer activated by calcium carbide slag are amorphous hydrated calcium silicate and hydrated calcium aluminate gel,which contribute to the improvement of compressive strength of solidified soil.The compressive strength of geopolymer solidified soil cured at -2℃ and -10℃ for 28 days is 69% and 76% lower than that cured at 20℃,respectively.Due to the expansion of the pores in the frozen state which is related to the ice crystal,the growth of cracks is promoted,the efficiency of geological polymerization reaction is reduced and the amount of polymerization products is reduced.Compressive strength of the samples increases with the increase of curing age,because of the more silicon-aluminum grid structures produced by the geological polymerization reaction,the lower the porosity of the solidified soil and the internal structure of the soil is intertwined to form a denser structure.The geopolymerization reaction is less affec

关 键 词：地聚物固化土 偏高岭土 电石渣 无侧限抗压强度 微观分析 

分 类 号：TU443[建筑科学—岩土工程]