Montmorillonite Content of Expansive Soils and Its Relationship with Swelling and Consistency Properties

As evident from many studies, mineralogical composition dominantly governs the behavior of expansive soils. Among several minerals, the influence of montmorillonite on swelling behavior is extensively investigated. However, studies focusing on montmorillonite quantification and deriving its exact influence on consistency and swelling behavior are scarce. With this in mind, expansive soil samples were collected from different regions in India and characterized for montmorillonite content (MMC). Based on the obtained results, relationships for MMC versus swelling and consistency property were developed. Interpretation of results reveals a distinct nature of natural expansive soils (NES) and mineral-rich bentonite soils (BS). It has been found MMC in NES is largely confined to 44%, while the same for BS is as high as 90% was reported. Similarly, liquid limit of  < 100% and plasticity index of  < 60% for NES and greater than these percentages for BS was identified has a benchmark for distinguishing between these soils. Furthermore, an increase in swelling potential, liquid limit, and plasticity index and a decrease in shrinkage limit and shrinkage index with an increase in MMC are found from the correlations. The analysis of results besides demonstrably confirming the marked influence of MMC also warranted the necessity to probe the presence of mixed layer minerals and their role on swelling and consistency behavior of expansive soils. The results presented in the study can help to decide suitable technique or additive to alter the behavior of expansive soils.