Permeation characteristics and impact factors of geopolymers made of kaolin

•Hydraulic conductivity of geopolymer mixed from DOE-based raw materials proportions is tested.•OH− (M) has the strongest effect on hydraulic conductivity, followed by SiO2, Na2O and OH−×Na2O.•MIP results reveal that OH− (M) greatly affected pore diameters in geopolymers, d50 varied tenfold.•SiO2 (mol) affected only proportion of small pores, but not overall distribution of pores.•A linear relationship exists between hydraulic conductivity and d50 of geopolymer (r2=0.98).