Performance Optimization of Flood Sediment Adobe Bricks Through Natural Additive Integration

This study addresses critical knowledge gaps in adobe construction by systematically investigating soil mineralogy–additive effectiveness relationships and developing dual-additive optimization strategies for flood sediment valorization. Four Thai soil types—Nakhon Pathom (NPT), Sisaket (SSK), Uttaradit (UTT), and September 2024 Chiang Rai flood sediment (CRI)—were characterized using XRD and EDS analyses. Twelve adobe formulations incorporating rice husk (3.45%) and graduated bentonite concentrations (5–15%) were evaluated for mechanical and thermal properties. UTT soil with balanced mineralogy (42.1% SiO2, 40.4% Al2O3) achieved optimal mechanical performance (3.12 ± 0.11 MPa compressive strength), while CRI demonstrated superior thermal insulation (0.200 ± 0.009 W/m·K). Rice husk systematically enhanced compressive strength across all soils (13.6–82.5% improvement) while reducing thermal conductivity to 0.211–0.278 W/m·K. Dual-additive optimization of CRI enabled application-specific customization: rice husk alone maximized strength (1.34 ± 0.09 MPa), while bentonite combinations optimized thermal performance (0.199 ± 0.015 W/m·K). Microstructural analysis revealed distinct reinforcement mechanisms and matrix densification effects. This research establishes predictive frameworks for material selection based on soil composition, demonstrates viable flood waste valorization pathways, and supports Thailand’s Bio-Circular-Green economic framework through sustainable construction material development.