Influence of Wet-Dry Treatment of Urena Lobata Fibers Reinforced Cement Boards

The impregnation of wood in fiber cement boards aims to replace traditional ceiling boards, which are prone to moisture damage over time. This study explores a modified hornification process involving fiber treatment with a solution of hexamine and gallic acid (H/G method) compared to a conventional hornification method (H method), where fibers are soaked in tap water. The objective is to evaluate the influence of this modified process on the morphological, physicochemical, and mechanical properties of <i>Urena lobata</i> (UL) bast fibers from the Littoral region of Cameroon. The fibers underwent four wet-dry treatment cycles using both the H/G and H methods. Results revealed significant reductions in water and moisture absorption compared to untreated (UT) fibers. Water absorption decreased from 227.79±0.05% (UT) to 200.34±0.05% (H) and 130.37±0.03% (H/G), while moisture absorption reduced from 9.286% (UT) to 7.03% (H) and 5.854% (H/G). Additionally, an increase in fiber density was observed, rising from 1.72±0.012 g/cm³ (UT) to 1.78±0.012 g/cm³ (H) and 1.87±0.04 g/cm³ (H/G), attributed to the infiltration of hexamine and gallic acid into the fiber cells. Mechanical performance was assessed through flexural and compressive tests after 7, 14, and 28 days of curing. Both elastic modulus and compressive strength improved progressively from untreated fibers through the H method to the H/G method, with increases of 20% and 30%, respectively. These findings demonstrate that the hexamine and gallic acid treatment enhances the effectiveness of the hornification process, significantly improving the water resistance and mechanical performance of the treated fibers.