Effect of coir husk fiber on rice husk ash and cement based peat stabilization

Abstract

This study examines the use of rice husk ash (RHA) and coir fiber as partial replacements for cement in stabilizing peat, a weak and organic soil common in tropical regions. Laboratory experiments were conducted using various mix proportions to evaluate unconfined compressive strength (UCS). A 30% cement and 70% peat mix served as the control. The optimal sustainable mix, which contained 25% cement, 0.5% coir fiber, and 4.5% RHA, achieved a UCS of 512 kPa, comparable to the control. Reducing cement to 20% with 1% coir fiber and 9% RHA resulted in a UCS of 331 kPa. However, a further reduction to 15% cement with 1.5% coir fiber and 13.5% RHA produced only 50.87 kPa, indicating that cement contents below 15% lead to inadequate strength. Fourier-transform infrared spectroscopy (FTIR) confirmed the pozzolanic activity of RHA. Life cycle assessment and cost analysis were conducted relative to the 30% cement mix and showed significant reductions in embodied energy, CO₂ emissions, and material costs with increasing RHA and coir content. The results demonstrate that locally available agro-industrial by-products can partially replace cement in peat stabilization, offering an effective and sustainable ground improvement method when properly proportioned.