The main objective of this research is to study the effect of stabilizing the soil, which classified as A-2-4 according to AASHTO soil classification system, with Ordinary Portland Cement (OPC), Cement Kiln Dust (CKD) and a new Liquid Chemical Soil Stabilizer (LCSS) on the flexible pavement structural design for many classes of highways in Egypt. CKD contents were 2%, 4%, 8% and 12% by soil dry weight. Whereas OPC contents were 2%, 4%, 6%, 8%, and 10%. To study the effect of the LCSS, the same contents of OPC and CKD were used with adding the LCSS, whose concentration was 1:1000 by volume of water. The resilient moduli of the treated and untreated soil were determined. According to the Egyptian Code for Urban and Rural Highways, the required flexible pavement sections for many classes of highways have been determined. For each case of the treated and untreated soil, the construction cost of one square meter of pavement has been estimated to study the economic feasibility of using OPC, CKD and LCSS as chemical soil stabilizers for flexible pavement construction purposes.