Experimental Investigations On The Strength Property Of Lime Stabilized Loess

Loess is a widespread problematic soil in China due to its collapsibility.Lime stabilized loess is widely applied in pavement base and foundation treatment,but the systematic research on its strength properties is seldom carried out.In this study,the effects of lime content,porosity and curing time on the unconfined compressive strength and shear strength of lime stabilized loess were studied by unconfined compressive strength test and triaxial compression test.Finally,the microstructure of lime stabilized loess with different curing time was also investigated by scanning electron microscope.The following conclusions are drawn:The unconfined compressive test results revealed that the curing time has a significant effect on the unconfined compressive strength of lime stabilized loess.For curing time no more than 7 days(i.e.3,5 and 7days),the influence of lime content on unconfined compressive strength of stabilized loess is not very obvious.A lime content of around 16% seems to lead to a maximum unconfined compressive strength within the range investigated.However,when the curing time is longer(like 28 and 90 days),unconfined compressive strength of the stabilized loess increases with the lime content.When the lime content is the same,unconfined compressive strength of the stabilized loess would grow almost linearly with the decrease of porosity.Correlation of unconfined compressive strength with lime content,porosity and curing time was also developed.The triaxial compression test revealed that the angle of internal friction is independent of the amount of lime,the porosity and the curing time of the specimen for a given lime stabilized loess.For lime stabilized loess with the same compactness and curing time of 7 days,the cohesion intercept increases first and then decreases with the increase of lime content.when the curing time is greater than or equal to 28 days,the cohesion intercept increases with the increase of lime content and the strength growth rate increases rapidly with age.The linear relationship could be used to characterize the relationship between the cohesion intercept and lime content for and the cohesion intercept of lime stabilized loess at with different ages is given.When the lime content is the same,cohesion intercept of the stabilized loess would grow almost linearly with the decrease of porosity,and linear relationship between the void ratio and the cohesion intercept of lime stabilized soil is also given.The relationship between porosity,lime content,age and cohesion intercept is established using the fitting regression of experimental data.The SEM photographs showed that in the early stage of curing,cationic exchange and crystallization mainly occur in lime-stabilized loess,which were manifested as the decrease of water film thickness on the surface of soil particles,and the formation of aggregation and a small amount of cementitious materials.Moreover the rod-like and fibrous structures on the surface of some soil particles or aggregation were observed.In the later curing stage,a series of pozzolanic reactions and carbonation occurred in the lime stabilized loess,which were manifested as the hardening of cementitious materials and the generation of hard crystals,so as to bring the lime stabilized loess to a higher density and integrity.