Expansive soils are problematic soils which pose a risk to the safety of civil engineering structures. These soils can be treated by compaction or by adding additives to the soil. Where the strength and properties of expansive soil cannot be improved via mechanical stabilisation (Compaction), a desirable strength can be achieved through the use of chemical admixture techniques. The swelling and shrinkage of expansive soils cause movement in the soil mass resulting in a deferential settlement in

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... engineering structures such as roads and building leading to cracks and subsequent failure leading to high cost of maintenance. Calcium based additives such as cement and lime have been used in expansive subgrade stabilisation to enhance the strength, reduce swell and subsequent differential settlement. However, the growing concerns on carbon dioxide (CO 2 ) emission and climate change have reignited the need for a more sustainable soil stabilisation techniques using waste materials. In this study, non-traditional expansive subgrade treatment techniques using sustainable waste materials with respect to their efficiency in improving the geotechnical engineering properties of the subgrade materials have been investigated and reviewed. This study also discusses the engineering problems associated with expansive soils, proposing an effective, efficient, cheaper and sustainable application of non-traditional stabilisers in expansive soil stabilisation. The study concludes that, the addition of non-traditional stabilisers in expansive subgrade stabilisation using chemical stabilisation techniques can improve the engineering properties of expansive subgrade materials.