Durability performance of foamed concrete strengthened with chemical treated (NaOH) coconut fiber

Abstract

Utilization of natural fibers in the construction industry will assist to attain a sustainable consumption pattern of building materials. Natural fibers are renewable, cost-effective, low in density, eco-friendly, non-abrasive and readily obtainable anywhere. Coir fiber is not commonly used in construction industry but is often discarded as wastes. Coconut fibres obtained from coconut husk, belonging to the family of palm fiber, is agriculture waste product obtained in the processing of coconut oil. It’s also available in large quantities in Malaysia. Therefore, this research in performed to examine the durability performance of foamed concrete strengthened with chemical treated coconut fiber. The effect of chemical treatment of coconut fiber at different percentages between 2-l0% wt. concentrations was examined expansively. Four parameters have been investigated which were moisture absorption capacity, porosity under vacuum saturation, ultrasonic pulse velocity and performance index. The study reveals that the optimum percentage of chemical treatment of fibers that lead to excellent durability properties was 6% wt. Enhancement in durability properties of foamed concrete is accredited to the improvement in fibers and interfacial adhesion after the chemical treatment process. The importance of alkali treatment is the commotion of hydrogen attachment in the fiber surface, thus amassed the surface irregularity. The cross section of coconut fiber was extremely transformed through the alkali treatment process in comparison with untreated fiber. The cross sectional area that undergoes alkali treatment was lesser compared to untreated fiber. Moreover, individually cell in the fiber cross section was transformed from a polygon shape to an oval shape, complemented a lot of gaps between the cells which at the same time improved the overall durability and mechanical performance of foamed concrete. A rougher coconut fiber surface is attained after the alkali treatment process in which it is beneficial for the interfacial adhesion between the fiber and cement matrix since a rougher surface facilitates in excellent mechanical interlocking. Alkali treatment also removes high percentages of oils, wax and lignin, which covered the outside surface of the fiber cell wall.