处治红黏土水-力性能的团粒尺寸效应  

Effects of aggregate sizes on hydro-mechanical performances of treated laterite

作　　者：谈云志[1] 胡焱 占少虎 刘伟[1] 明华军[1] TAN Yun-zhi;HU Yan;ZHAN Shao-hu;LIU Wei;MING Hua-jun(Yichang Key Laboratory of the Resources Utilization for Problematic Soils,China Three Gorges University,Yichang 443002,China)

机构地区：[1]三峡大学特殊土资源化利用宜昌市重点实验室,湖北宜昌443002

出　　处：《岩土工程学报》2021年第12期2323-2329,共7页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51579137)。

摘　　要：红黏土因高黏粒含量和高含水率而易于成团,当掺入石灰或水泥处治时,会存在拌和不均的难题,进而影响处治效果。选择4组红黏土,其最大团粒尺寸D为5.0,2.0,1.0,0.5 mm。按照干质量比,偏高岭土∶石灰∶红黏土=5∶5∶90配置试样。然后,喷入蒸馏水增湿到含水率33.2%;最后,压实成型养护至预定龄期,再开展水-力性能和微观特性等试验。结果表明,随着最大团粒尺寸变大,处治红黏土线收缩率增大、无侧限抗压强度降低;但掺入偏高岭土后,相同团粒尺寸的处治土收缩性得到抑制,强度也得到提升。究其原因,红黏土团粒尺寸大,石灰只能附着在团粒的表面,仅形成团粒间的"桥接",不能形成包络状胶结;偏高岭土含有大量无定形的硅、铝氧化物,具有高"火山灰"活性,可以快速捕捉水化石灰中的钙离子,形成硅、铝酸钙等胶结物;同时,偏高岭土还充填了团粒间孔隙,二者的联合作用增强了处治红黏土的水-力性能。The laterite is prone to aggregates due to the possession of high-content clay and moisture.It may be difficult to mix uniformly when lime and/or cement is added into the laterite,and further influences the treated effects.Four groups of laterite are selected,with the aggregate sizes of 5.0,2.0,1.0 and 0.5 mm,respectively.The mixing ratio of metakaolin-lime-laterite is 5∶5∶90 in dry weight.Then,the mixtures are moistened to the predetermined water content of 33.2%using distilled water.Finally,the hydro-mechanical performances and microstructure tests on the laterite specimens are carried out after compacted and cured to predicted periods.The results show that the linear shrinkage increases and the unconfined compressive strength decreases with the increasing of the aggregate size of the treated laterite.However,the inhibition of the shrinkage and the enhancement of the strength appear after adding metakaolin into the treated laterite with the same aggregate size.This may be ascribed to the following reasons,lime just adheres to the surface of the laterite aggregates,which only forms“bridging”linkage between the aggregates,and does not develop enveloping cementation.The metakaolin,containing plenty of amorphous silicon and aluminum oxides,can quickly capture the calcium ions in calcium hydroxide solution and form cementation hydratessilicon and calcium aluminate owing to having high pozzolanic activity.Meanwhile,the metakaolin also play a role of filling into the inter-pores of soils.Both of them improve the hydro-mechanical performances of the treated laterite.

关 键 词：红黏土 团粒尺寸 偏高岭土 石灰 水-力性能 

分 类 号：TU43[建筑科学—岩土工程]