Freeze-thaw Resistance and Deterioration Mechanism of Cement-treated Mixture of Soda Residue and Clay
To promote the engineering application of cement-treated mixtures of soda residue and clay(CMSRC)in seasonal freezing regions,the freeze thawing(F-T)resistance of CMSRC,located above or below the saturation line of the capillary water,was investigated in this study.Accordingly,two kinds of dry and wet F-T cycle conditions were set,and experiments including 0-8 F-T cycles were conducted.Changes in the volume,mass,and appearance of CMSRC during the F-T cycles,as well as the evolution of the unconfined compressive strength(UCS)and water content after different F-T cycles were explored.The deterioration mechanism of F-T cycles was analyzed via scanning electron microscopy.Under 8 cycles of dry F-T,the volume exhibited freeze shrinkage and thaw expansion,with a small overall change;the mass generally presented a downward tendency,with a small change in overall quality;the UCS gradually decreased,and the bearing damage ratio(BDR)was 81.6％after 8 cycles.The water migrated inward,with 0.72％increase in water content at the center,and the appearance remained almost unchanged.However,under 8 cycles of wet F-T,the volume demonstrated freeze expansion and thaw shrinkage,expanding 5.45％after 8 cycles.The mass loss was significant,of 2.87％after 8 cycles;the UCS gradually decreased then stabilized,and the BDR was approximately 65％;the water migrated outward with 2.57％decrease in water content at the center,the surface cracks grew and peeling developed gradually.The better F-T resistance of CMSRC is due to its strong density,with the spaces in the SR filled with clay,and cement hydrate further strengthening the connection of soil particles.Under the action of F-T cycles,water migration and cycled phase conversion significantly damaged the microstructure of CMSRC.Thus,it is recommended that CMSRC can be used above the vadose zone in the seasonal frozen region.
subgrade engineeringdeterioration mechanismfreeze-thaw cyclecement-treated mixture of SR and clayphysical propertystrength performance
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