Utilize Xanthan gum for enhancing CBR value of used cooking oil-contaminated fine sand subgrade soil for pavement structures

Abstract

Used Cooking Oil (UCO) that mixes with soils can weaken its engineering properties. This paper investigates stabilizing UCO-contaminated fine sand natural soil to be used as subgrade layer in road pavement structures. Xanthan gum is utilized as the stabilizing material. Stabilization is evaluated in terms of the soil’s California Bearing Ratio (CBR). It is found that the increase in Xanthan gum content (Xc) enhances the CBR value of UCO-contaminated fine sand soils. Generally, results indicated that at any Xc value between 0.1 and 0.9%, UCO-contaminated fine sand soil samples with lower CC values have higher CBR. The effective content of Xanthan gum powder to enhance the soil’s CBR value is found to be 0.4%. Considering Xcof 0.4% and UCO contamination content (CC) of 0.2%, it is indicated that the soil’s CBR value increases by 304% and 149.4% of the CBR value of natural sand soil and UCO-contaminated sand soil in order. In addition, Xc of 0.9% updates the unconfined compressive strength to 10.1 kPa and 7.6 kPa for soil samples with CC = 2% and 8%, respectively. Durability study shows that wet and dry cycles decrease the CBR of fine sand stabilized soil. The trend of CBR reduction in wet cycles is higher than that of dry cycles. Economically, stabilizing UCO-contaminated fine sand soil reduces the required pavement thickness by about 11.3%. On the other hand, the paper introduces a contour map and general mathematical model to estimate the CBR value of in terms of Xc and CC.