Performance of ground improvement projects incorporating sustainable reuse of geo-composite wastes

Green geotechnical construction can have a significant contribution to the sustainability and resilience of infrastructural projects. As the amounts of wastes produced from different construction and mining activities continues to increase exponentially, green geotechnical applications incorporating waste and recycled materials become essential to minimize materials sent to landfill while reducing demand on natural resources. This paper investigates the use of geo-composite admixture produced from recycled materials in ground improvement projects. The developed geo-composite admixture is comprised of coal ash, blast furnace slag, and recycled bassanite to optimize the formation of ettringite within the soil matrix. The geo-composite admixture was mixed with small ratios of cement-soil to retain its stability in wet environment. The effect of geo-composite on the strength of stabilized soil is evaluated through unconfined compressive strength tests. The results demonstrated the effectiveness of the developed geo-composite admixture in stabilizing soft clay soils. As the admixture ratio increased, the soil mixture strength and dry unit weight increased while its water content decreased. The formation of ettringite enhanced as the admixture ratio in soil mixtures increased. The ettringite plays an important role in the permanent strength improvement of stabilized soil. Increasing the morphology of ettringite in soil matrix due to increased length of ettringite needles, which enhances interlocking of soil particles and consequently improves strength of soil mixture. Based on the achieved results, it is recommended to incorporate the developed geo-composite admixture in earthwork structures for more sustainable and resilient construction.