Subgrade Stabilization using Rice Husk Ash-based Geopolymer (GRHA) and Cement Kiln Dust (CKD)

Abstract This study explores the use of two wastes (rice husk ash (RHA) and cement kiln dust (CKD)) for improving the mechanical strength of a subgrade soil obtained from a failed road section in Nigeria. It presents an experimental insight on the stabilization of the soil with CKD and CKD + RHA-based geopolymer. In the RHA-based geopolymer, CKD was included as supplementary material for activator reduction. The stabilizers were mixed with the soil in varying proportions ranging from 7.5 to 15% for CKD stabilization. Thereafter, the optimum percentage of CKD was mixed with RHA (4–10%) and activated with sodium hydroxide (NaOH). Pavement design was also performed using PaveXpress considering heavy traffic loading conditions. Cost analyses were conducted on the resulting asphaltic pavement thickness for each subgrade. The results show improved mechanical with both stabilizers. However, the stabilization done with CKD at 10 % and geopolymer 3 (8 % RHA and 10 % CKD) were the optimum. Generally, CKD stabilization performed better than geopolymer stabilization. Also, the results showed that the pavement with the lowest thickness corresponds to the optimum and had the highest cost reduction. This research showed that $60,000 can be saved irrespective of stabilizer used which is in tandem with sustainable development goals (SDGs 9, 11 and 12).