This study aims to analyze the effect of NaOH molarity variation (13 M, 14 M, 15 M, 16 M, 17 M) on the mechanical properties, porosity, and permeability of fly ash-based geopolymer porous concrete. The experimental method involved casting cylindrical samples (Ø10 cm × 20 cm) using coarse aggregates (9.5–12.5 mm), an alkali activator/fly ash ratio of 0.45, and oven curing at 80°C for 24 hou…