An alternative approach for the use of DDL theory to estimate the swelling pressure of bentonites

• Laboratory swelling pressure tests were carried out on bentonites.
• Swelling pressures of compacted bentonite were derived using double layer theory.
• Comparison of experimental and calculated swelling pressures.
• New equations derived on basis of calculated and experimental swelling pressures.
• A good agreement was observed in all cases between experimental derived equations.

An approach to estimate the swelling pressure of compacted bentonite (Bent) using Gouy–Chapman diffuse double layer theory is presented. Several laboratory swelling pressure tests on compacted Bent (MX80 and Calcigel) under constant volume conditions were performed and compared with the calculated swelling pressure using the original theory. The study revealed that at low dry density the as prepared total void ratios are less than theoretical void ratios using diffuse double layer theory, however, reverse behavior has been noticed for high compaction dry densities. Based on the experimental results of Bent with different valences, the relationship between the theoretical void ratio from diffuse double layer theory and as prepared total void ratio were determined. New equations were derived on the basis of diffuse double layer theory and experimental swelling pressure data. The method categorizes the different Bents into two groups depending upon the weighted average valency. A good agreement was observed in all the cases between experimental and estimated swelling pressure using derived equations. The applicability of the proposed method was investigated by comparing the estimated swelling pressure results with the additional reported in literature laboratory results on swelling pressure of compacted Bent.