Permeability and expansibility of natural bentonite MX-80 in distilled water

► We develop a Kozeny-Carman-like equation to describe the hydraulic permeability of bentonite MX-80 in distilled water. ► We apply a dynamic force balance model to describe the expansibility of bentonite MX-80 in distilled water. ► We use two strategies to account for both physical and chemical effects of the accessory minerals in bentonite MX-80. ► The approach taken makes the model work well in predicting the expansibility of bentonite MX-80 in distilled water.