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Comparative Evaluation of Micro-Metakaolin and Ferric Chloride Solution in Stabilizing Expansive Soils

Expansive soils are generally characterized by their volume change when subjected to variation in water content. This may result in significant damage to supported and nearby structures. In this study, the swelling properties of bentonite material as an expansive soil are first determined. The expansive soil is then improved using two different approaches, namely, micro-metakaolin and ferric chloride solution. The optimum percentage for both additives are determined using laboratory experiments. These percentages are found to be 25% and 1% for the micro-metakaolin and the ferric chloride solution, respectively. The free swell index of the bentonite after being treated with micro-metakaolin and ferric chloride solution at the optimum percentages are found to decrease by about 54% and 62%, respectively. Meanwhile, the swelling pressure for the expansive soil decreased by 33% and 43% when mixed with the same optimum values of micro-metakaolin and ferric chloride solution, respectively. Based on the results obtained in this study, the addition of ferric chloride solution achieved better results compared to micro-metakaolin. This improvement technique may be used to enhance the properties of expansive soils that support different construction engineering projects.