This paper investigates an experimental study of cement-stabilized lateritic soil (CSLS) for road construction. The investigation focused on the mechanical properties and the potential of using biomass bottom ash (BBA) as aggregate materials based on the soil-cement standard of Thailand. CSLS specimens were prepared with different contents of BBA (40%, 60%, 80%, and 100%) and hydraulic cement (3%, 5%, and 7%). A series of unconfined compression tests were carried out to present the strength development of the mixtures. The strength development index value indicated the feasibility of using BBA as aggregate materials with the replacement of the lateritic soil (LS) mass by 60% or more. The replacement of LS by BBA of 80% with 5% cement for soil-cement subbase, and 7% cement for soil-cement base courses, is recommended.