Salt expansion induced by pore relative humidity in dry sulfate-rich silty

Abstract

Sulfate heave induced by moisture and soil structure destabilization is not conducive to engineering safety. The contribution of pore relative humidity (PRH) on inducing salt expansion has been widely concerned, but its induction in dry sulfate-rich silty (DSRS) remains unclear. In this paper, the effects of PRH on the salt expansion behavior of silty were studied. Influences of salinity, temperatures and PRH on the salt expansion displacement (SED), salt expansion rate (SER) and salt expansion growth rate (SEGR) of DSRS were investigated. The X-Ray Diffraction (XRD) technique and salinity migration and redistribution test were performed to analyze the mineral compositions and variations in salinity. Results show that the SED, SER and SEGR of DSRS increased with the increase of PRH and salinity, decreased with the temperature rising. The largest increments of SED and SER occurred in the PRH of 80–90%. The formation of the inflection points implied that PRH has limitations in enhancing salt expansion. XRD results showed that the existence of mirabilite and thenardite verifies the salt expansion behavior of DSRS affected by PRH. The upward trend of post-experiment salinity distribution further verifies the enhancement of PRH on salt expansion. All results provide a fire-new perspective to cognitive the impacts of PRH on salt expansion in DSRS, which is of great significance to the safe utilization and effective treatment of DSRS.