Calcium Carbide and Wood Ash as Environmentally Friendly Soil Stabilisers for Enhanced Subgrade Performance

This study looks at the potential of waste calcium carbide (WCC) and wood ash (WA) as soil stabilisers to improve the engineering characteristics of subgrade soil. The investigation begins by characterising the properties of the untreated soil, indicating a liquid limit of 24.6%, linear shrinkage of 7.6%, and a non-plastic nature due to the lack of a plastic limit. In addition, the soil composition comprises a mere 2% of small particles measuring less than 63 µm, while a substantial 74% of the particles fall within the range of 63 µm to 2 mm. The particle density of untreated soil is found to be 2.86, beyond the typical soil limitations. Subsequently, an investigation was conducted to examine the impact of WCC and WA on Atterberg limits, compaction characteristics, and California Bearing Ratio (CBR) values. The findings indicate that the incorporation of WCC and WA leads to a reduction in the liquid limit by a maximum of 18.70% and linear shrinkage by a maximum of 55.26%. Compaction properties show an increase in optimal water content (OWC) and a minor decrease in maximum dry density (MDD). Importantly, CBR values significantly improved, with the soil treated with 6% WCC and WA demonstrating a CBR value of 26.9%, exceeding the subgrade acceptability requirement in road construction. This study highlights the potential of WCC and WA as cost-effective and sustainable soil stabilisers, particularly in areas where traditional stabilising materials are limited. More research into optimisation and long-term performance can help to realise the full potential of this novel method for soil stabilization.