Experimental study for temperature effect on swelling pressures during saturation of bentonites

Swelling pressure tests were conducted at 25, 50, and 80°C to elucidate the temperature effect on swelling pressures at peak, valley, re-peak and equilibrium points (ppeak, pvalley, pre-peak, and peq) in swelling pressure evolution curve. Three powder bentonites (Kunigel-V1, Volclay, and Kunibond) and two granular bentonites (MX-80 and Kunigel-GX) were used to investigate the grain size effect on ppeak, pvalley, pre-peak, and peq at different temperatures. Experimentally obtained results were the followings. 1) For the powder bentonites, ppeak, pvalley, pre-peak, and peq increased with the increase of dry density and rose with increasing temperature; 2) For the granular bentonites, ppeak, pvalley, pre-peak, and peq decreased as temperature rose and increased as dry density rose; 3) All five bentonites were found to have larger values for (peq-pvalley) at higher dry density and lower temperature conditions. Swellings and montmorillonite fabric unit interactions during saturation were discussed with swelling pressure evolution curve. Temperature effect on peq was carefully explained.