Evaluating swelling behaviour and durability of geopolymerised expansive soils under cyclic moisture conditions

The University of Sydney, School of Civil Engineering, Shepherd Street, Darlington, 2008, NSW Australia

^* Corresponding author: hamed.faizi@sydney.edu.au

Abstract

Soil stabilisation plays a vital role in ensuring the long-term stability and performance of light- weight infrastructure such as railways and roads constructed over unsaturated expansive soils. These soils are highly susceptible to swelling and shrinkage caused by seasonal moisture fluctuations, leading to structural damage, differential settlement, increased repair and maintenance costs, and reduced service life. This study investigates the potential of agro-industrial aluminosilicate byproducts, including fly ash and slag, as alternatives to the CO2-emitting and energy-intensive cement for improving the behaviour of unsaturated expansive subgrades. A series of laboratory experiments were conducted to evaluate the effects of geopolymerisation on the swelling and water absorption behaviour of stabilised soils. To simulate field conditions, the impact of cyclic wetting and drying was assessed, providing insights into the performance of stabilised soils under moisture fluctuations. The findings reveal that geopolymerisation reduces swelling potential and water absorption capacity of expansive clays. However, a gradual increase in swelling was observed in stabilised soils as wetting and drying cycles progressed, suggesting a need for further investigation into the long-term behaviour and stability of these materials.