Enhancing fire resistance in wood with high-water retention silica gel: A promising flame-retardant solution

Abstract

This study aims to evaluate the water retention and flame-retardant properties of silica gel prepared using anionic polyacrylamide (HPAM), gluconate-delta-lactone (GDL), and aluminum citrate (AlCit). Silica gel samples were synthesized with sodium silicate (8 wt%), sodium bicarbonate (4 wt%) and varying concentrations of HPAM (0.2-0.8 wt%) and GDL (0.1-0.3 wt%). The prepared gels were characterized using XPS, XRD, FTIR, and TGA. Optimal water retention capacity was achieved with 0.4 wt% HPAM and 0.2 wt% GDL. Compared to traditional gels, silica gel has more surface water molecules due to additional hydrophilic groups and the amorphous nature of silica. At high temperatures, silica forms a layer with the charcoal from treated wood combustion, inhibiting oxygen penetration and minimizing further combustion. After combustion at 500°C, the mass loss of wood treated with silica gel is 36–53% less than untreated wood, indicating greater weight retention and demonstrating silica gel's effectiveness in preventing continued burning.