Strength Properties of Clay Treated with Fiber and Biopolymer Subject to Freeze–Thaw Conditions

Nowadays, there has been growing demand for sustainable and carbon neutral stabilization techniques due to rising of environmental awareness. This study aims to develop a sustainable and environmentally friendly stabilization method to mitigate the ecological impact associated with cement production used to stabilize soft earthen materials in cold regions. An experimental study was designed to determine the performance of a biopolymer–fiber combination from different aspects. The main objectives of this study were to determine optimum fiber-biopolymer ratios and to compare the effectiveness of two different biopolymers when combined with fibers under freeze–thaw conditions. Xanthan gum and guar gum were selected for stabilization with biopolymer contents of 0.5% and 1% by dry weight of clay. Fiber-reinforced specimens were prepared with fiber ratios varying from 0.25% to 1.0% by dry weight of clay. After preparation of specimens, treated specimens were cured in a humidity-controlled room for 1, 7, and 21 days before being subjected to 5 and 10 freeze–thaw cycles. Despite guar gum-containing specimens showing greater strength without fiber inclusion, xanthan gum-contained clay specimens performed better with fiber inclusion. The efficient xanthan gum/fiber ratio was obtained as 1% xanthan gum and 0.5% fiber content for clay, considering the strength loss after freeze–thaw attack. Last, significant increases in strength have been observed, up to 5.8 times, when gum binders are combined with fiber for earthen stabilization. Further, the strength loss is reduced by up to 8% after freezing–thawing.