Waste hemp stabilisation of expansive soils: behaviour and sustainability assessment

This study investigates the effects of waste hemp stalks on expansive clay soils. Hemp, a biodegradable and sustainable material, was used at 5%, 7.5%, and 10% by dry weight to stabilise a clay mixture (70% kaolin, 30% bentonite). Laboratory tests, including Atterberg limits, compaction, and consolidation, were conducted in accordance with ASTM standards. Results show that hemp additives significantly reduced liquid limit, plasticity index, swelling percentage, and swelling pressure. The optimal performance was achieved with 10% T1 hemp, reducing swelling from 25% to 0.10% and swelling pressure from 40.64 kPa to 5.08 kPa. These findings demonstrate the potential of waste hemp as an alternative bio-based stabilisation material to traditional stabilisers. A comparative analysis with cement- and lime-based stabilisers highlights hemp’s advantages in reducing costs and mitigating carbon footprints.