<p>Compacted bentonites are potential buffer materials in the design of multi-barrier nuclear waste disposal repositories. The present study investigates the significance of mineralogy and pore structure on the liquid limit and shrinkage limit, and swelling pressure evaluation of compacted Barmer and Bikaner Indian bentonites. A series of constant-volume swelling pressure tests were carried out at various dry densities between 1.4 and 1.8&#xa0;Mg/m³ on both the bentonites. To understand the swelling pressure evaluation, the fabric investigation (morphology, and pore size distribution PSD) of the bentonites was conducted at different stages of swelling pressure using FESEM and MIP tests. A comparison study was carried out for the Atterberg limits and swelling pressure evaluation results of the present study with other globally prominent bentonites from the literature. The results concluded that the mineralogy (montmorillonite, palygorskite) and associated pore structure play an important role in the liquid limit and shrinkage properties of bentonites. The correlations among the different parameters, such as liquid limit, shrinkage limit, specific surface area, cation exchange capacity, and smectite content of Na⁺ dominated bentonites, were found to be different from divalent Ca²⁺–Mg²⁺ dominated bentonites. The swelling pressure evolution behaviour, i.e., the monotonic and intermediate collapse behaviour of compacted bentonites, was noted to be strongly dependent on moulding compaction pressure and associated mineralogy and PSD (macropore volume). On a semi-logarithmic scale, irrespective of bentonite type, macropore volume decreased linearly with increasing compaction pressure, while swelling pressure increased linearly as macropore volume decreased.</p>