Thermal Performance of Natural Fiber-Reinforced Geopolymer Concrete

Malaysia has a hot tropical climate; hence, the energy required to cool buildings increases daily. Therefore, an attempt was made to produce an eco-friendly construction material with good thermal performance. Geopolymer concrete (GPC) reinforced with two different types of natural fibers, kenaf fiber (KF) or coconut fibers (CFs), was introduced as insulation material. The proposed concrete mixtures were subjected to a non-destructive thermal test using a hotbox apparatus. Three panels of 100 mm thick were fabricated; the first panel consists of GPC as control, the second panel consisted of GPC with 1% KF, and the third panel consists of GPC with 0.75% CF. The composite that achieved the best test performance was selected and used to fabricate different thicknesses, 75 and 50 mm. The results showed that the compressive strength of GPC prepared with KF was 2.4 and 5% higher than that of GPC with CF at 7 and 28 days, respectively. Moreover, the thermal conductivity of GPC prepared with KF was more effective than that with CF which was lower by 3.8%, while compared to GPC without fiber, the thermal conductivity of geopolymer kenaf fiber decreased by 7.1%. In addition, the decrease in the thickness of the panel leads to a decrease in the thermal conductivity by 23% and 42% of 75 mm and 50 mm, respectively. In conclusion, the addition of KF to GPC can improve compressive strength and thermal insulation. Hopefully, this compound provides the industry with an alternative material of high thermal resistance for wall panels.