Stabilization of Construction and Demolition Waste with High Fines Content Using Biopolymer

Construction and demolition waste fines (CDWF) are underutilized and problematic by-product of construction activities, often ending up in landfills due to difficulties in handling, limited structural value, and contamination. This study investigates the potential of xanthan gum (XG), a biodegradable biopolymer, to stabilize CDWF and enhance its mechanical properties. CDWF specimens were treated with varying XG contents (0.5%–3.0% by dry weight) and cured for 7, 14, and 28 days under controlled temperature and humidity. Unconfined compressive strength (UCS) tests and microstructural analyses using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were conducted. Results revealed that strength increased with curing time and XG content up to 2.0%, beyond which strength declined. SEM images showed gel bridging between particles, and EDS analysis revealed calcium and silicon migration toward the biopolymer matrix, indicating both physical and chemical interaction. These findings suggest that xanthan gum is a promising eco-friendly binder for reusing CDWF in geotechnical applications, contributing to sustainable construction and landfill diversion.