This research presents the potential of combined carbon capture alongside compressive strength improvement in carbonated lime treated kaolin clay, and determines the suitability of the strength improvement for application to capping layer in road pavement. Using combined modification and carbonation treatment at controlled air voids, 4.7%-10% calcium carbonate was determined in kaolin treated with 4-8% calcium hydroxide contents in samples at 10% air voids. Strength increase was achieved in carbonated lime-treated kaolin from 170 kPa to 280 kPa compared with soaked non-carbonated lime treated kaolin, which shows significant increase of approximately 65%. This method of combined modification and carbonation in lime treated clay has the potential to capture carbon alongside improving the strength of the weak kaolin, and could be effectively used for combined carbon capture and road pavement functions.

Carbonation of lime modified soil could capture carbon dioxide (CO_2) alongside strength improvement for road pavement materials. Due to large amounts of 〖CO〗_2 emissions and increasing cost of primary soil stabilizers such as lime and cement, the use of lime-based wastes have been encouraged. This paper reviews waste materials based on separate potential for 〖CO〗_2 capture and strength improvement of soils. Such wastes include cement kiln dust (CKD), saw dust ash (SDA), steel slag, basic oxygen steel (BOS) slag, ground granulated blast furnace slag (GGBS), coal fly ash (CFA) and cattle bone powder (CBP). Based on separated considerations of 〖CO〗_2 capture and strength improvement, CKD, SDA, BOS and GGBS have shown to have both high 〖CO〗_2 capture and strength improvement potential for weak soil. Future laboratory studies on lime-based waste (such as CKD and SDA) treated soil for combined 〖CO〗_2 capture and strength improvement need to be conducted.