The effect of soil stabilization on highway pavement thickness and cost

In this study, the effects of a soil stabilized with silica fume (SF) and bottom ash (BA) on highway pavement thickness and cost were investigated. For this purpose, SF on the ground at the rates of 2.5%, 5%, 10%, 15%, 20%, 25% and 30% by weight; Mixture samples were prepared separately with water and alkaline activator solution (AAS) by adding 5%, 10%, 15%, 20% and 25% BA. The samples were first subjected to the standard proctor test, followed by 1, 7 and 28 day curing times, followed by unconfined pressure (UCS) and California Transport Ratio (CBR) tests. According to the unconfined pressure and CBR test results, the most effective additive ratios were determined as 25% SF+AAS and 15% BA+AAS. Based on the CBR values of these ratios, highway flexible and rigid pavement layer thicknesses were calculated using the AASHTO (1993) method and cost analysis was made. Compared to the pure soil, the flexible and rigid pavement thicknesses for the 25% SF+AAS added soil decreased by 38.88% and 25%, respectively, while the road construction costs decreased by 21.58% and 25%, respectively. Similarly, flexible and rigid pavement layer thicknesses for 15% BA+AAS added soil decreased by 40.74% and 22.5%, respectively, while road construction costs decreased by 19.74% and 22.5%, respectively.