Performance of marble powder – Nano silica stabilized clay

Clayey soils often exhibit unfavorable engineering characteristics such as low bearing capacity, high plasticity, and significant swelling, which limit their direct application in pavement and foundation construction. Soil stabilization is widely adopted to enhance the performance of such problematic soils. This study evaluates the effectiveness of marble powder, an industrial waste material, and nano- silica, a highly reactive nanomaterial, as stabilizing agents for clayey soil. A series of laboratory investigations were conducted on natural and stabilized soil samples with varying proportions of marble powder and nano-silica. The experimental program included Atterberg limits, Standard Proctor compaction, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and Free Swell Index (FSI) tests, performed in accordance with relevant Indian Standard codes. The results demonstrate that the incorporation of marble powder leads to a reduction in plasticity and an improvement in compaction characteristics, while nano-silica significantly enhances strength through micro-level bonding and pozzolanic reactions. An optimum stabilizer combination of 10% marble powder and 0.5% nano-silica was identified, yielding maximum strength improvement and a substantial reduction in swelling behavior. The findings indicate that the combined use of marble powder and nano-silica provides a sustainable, cost-effective, and environmentally friendly approach for improving the engineering performance of clayey soils for subgrade and foundation application.