Flexural Strength and Porosity of NaOH-Treated Maize Stalk Cellulose-Fibers-Reinforced Geopolymer Composites

This study characterizes the flexural strength and porosity of NaOH-treated maize stalk cellulose-fibers-reinforced geopolymer composites. Flexural strength tests are conducted, and the fracture surfaces of the composite and geopolymer powder are observed using a scanning electron microscope (SEM). Moreover, porosity analysis is also performed using Image J software from SEM images. The formation of geopolymer is confirmed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The addition of 1.5 wt% of NaOH-treated maize stalk cellulose fibers improves flexural strength by 2.4 times. The results show that the main failure mechanisms, namely fiber breakage, fiber pullout, and debonding of the fiber and matrix, can increase flexural strength and reduce failures during service life. During the analysis for fiber and particle pullout, SEM images under 25^2 pixels of pore areas are not considered, and an average porosity of 36.7% is achieved.