Efecto de la sulfidez en la respuesta a flexión de tableros de cemento reforzados con fibras de guadua angustifolia kunth pre-tratadas alcalinamente

Guadua angustifolia KUNTH is a giant grass native to America with high ecological adaptability. Its composition and structure make it in a lignocellulosic source with good mechanical properties with wide applications. Guadua angustifolia fibers were alkali pretreated by Kraft pulping at low temperatures. An amount of 10% of active alkali was combined with three different sulphide levels-10%-15%, and 30%. A mass portion of 5% of pretreated fibers was used to reinforce the fiber cement board composites produced by the slurry method. The effects of sulfidity concentration in treatment over the physical-mechanical properties of fiber cement board composites were evaluated. Superficial changes on Guadua fiber and water retention value after alkaline treatments were determined. Fiber cement boards were mechanically tested after 7, 28, and 180 days of curing. Results showed flexural strength in boards reinforced with treated fibers is greater than flexural strength in boards reinforced with untreated fibers; moreover, after 180 days of curing, there was no flexural strength reduction, indicating that alkaline treatments avoid fiber degradation into the cement matrix. Finally, results showed that low sulfidity concentration (10%) produces fibers with cleaner surfaces, improving fiber-cement bonding, and these fibers allowed the production of fiber cement boards with higher flexural strength.