Mechanical Properties of Geopolymer Composite Reinforced Kenaf Fiber

Abstract

This paper describes the physical and mechanical properties of geopolymer composite reinforced with kenaf fiber (1, 3, and 5 wt.%). Kenaf fiber was surface treated using sodium hydroxide 2M with 24 hours prior to mixing process. Test results showed that density, porosity and water absorption of geopolymer composites mixed with surface-treated kenaf fiber and those mixed with surface-untreated kenaf fiber are almost identical. Interfacial adhesion between fibers and matrix plays a critical role on mechanical performance of the natural fibers reinforced geopolymer composites. The degradation of reinforced fibers due to alkaline attack may result in existence of micro-crackes at the fiber and matrix interface. As surface treatment can diminish the alkaline sensitive component from the kenaf fiber and increase the surface roughness, the treated kenaf fiber geopolymer composite yields the mechanical properties better than the untreated kenaf fiber geopolymer composite does. Comparing with the geopolymer without fiber reinforcement, the flexural strength of the treated kenaf fiber geopolymer composites are 107%, 276% and 311% and that of untreated kenaf fiber geopolymer composites are 19%, 133%, 236% for 1%, 3% and 5% fiber, respectively.