The effect of geopolymer on loess soil stabilization (Case study; Loess soil of Gorgan province)

Losses are among the collapsible soils that, if saturated, their volume will rapidly drop. Iran is one of the countries where Loess soils are spread in different parts of it. The purpose of this study is to improve the strength parameters of loess Gorgan (North of Iran) using different ratios of geopolymer (a combination of loess and metakaolin). For this purpose, in this study, in addition to conducting index tests, a series of uniaxial compressive strength, Brazilian tensile strength, compressive wave velocity and modified compaction tests have been done. Furthermore, SEM, EDX and XRD tests have been conducted to investigate micro-structural features of non-stabilized and stabilized soils. In the samples stabilized with geopolymer, with increasing ratio of loess to metakaolin and the curing time (with fix alkaline activator solution), uniaxial compressive strength, tensile strength and compressive wave speed decreases. So that, with increasing curing time, the uniaxial compressive strength of the specimens decreased to 0.83 and the rate of this decrease was greater in the first 7 days. The results of XRD analysis and SEM images show that the disperse structure of loess soil is altered by the addition of geopolymer and by the production of alumina-silicate gel which results in increasing strength, decreasing porosity and homogeneity of loess soil structure.