Stabilisation of expansive soils subjected to moisture fluctuations in unsealed road pavements

Unsealed roads are an important asset providing the necessary connections between regional and metropolitan regimes of a country. However, these roads are affected by severe moisture fluctuations and recurring traffic loads that result in excessive maintenance. Unsealed road pavements are generally partially saturated during their service life, resulting in distinct volume and strength changes subjected to saturation changes. This paper investigates the capability of a novel stabiliser in reducing the adverse impact from moisture fluctuations and dynamic traffic loads on unsealed road pavements using an experimental and modelling approach. Firstly, a series of physical and mechanical tests were conducted on enzyme stabilised soil to explore its response under various saturations and its ability to suppress volume change. The application of subgrade stabilisation was then simulated using a verified modelling approach to assess the effectiveness of the novel stabilisation methodology for constructing unsealed road pavements. Finally, an analytical model was proposed to predict the performance of unsealed roads constructed on stabilised expansive subgrades subjected to loading and moisture cycles. The research highlights the importance of considering the effect of moisture fluctuations in pavement design and the possibility of adopting soil stabilisation for improved performance of unsealed roads constructed on expansive subgrade soil.