The waste materials such as fly ash, construction demolition waste, and plastic waste are generated in tremendous quantities and are dumped haphazardly thereby causing irreparable damage to the environment. Proper utilization of these wastes particularly in the construction sector will protect the environment from their harmful effects and will prove to be economical through the preservation of precious natural resources. This paper presents an investigation on the utilization of lime, fly ash, and construction demolition waste individually and in combination with each other for the stabilization of poor soil. The utilization of plastic waste along with soil-fly ash-construction demolition waste-lime composite was further investigated. The samples for unconfined compressive strength and split tensile strength were compacted at optimum moisture content to maximum dry density, which was obtained from standard Proctor compaction tests. The samples were tested after 7 days, 28 days, and 56 days of curing periods. The results reveal that the addition of admixtures increases the unconfined compressive strength and split tensile strength, and the optimum mixes were selected based on 7 days of unconfined compressive strength. The increase in strength with the addition of admixtures depends on the type of admixture used and the formation of new minerals, which can be observed from XRD graphs. The soaked California bearing ratio tests were conducted on the optimum mixes and soil-fly ash-C&D waste-lime mix was selected as the best sub-grade material compared to other material combinations based upon economic and environmental considerations.