Compaction and Strength Characteristics of Bentonite Rock-Quarry Dust Mixtures

The paper investigates the compaction and unconfined compressive strength (UCS) of bentonite-rock quarry dust (B-Q) mixtures for assessing the suitability of a cost-effective material for landfill liner. There is a criterion that the UCS of greater than 200 kPa is desirable for liner material for landfill applications to account for the load placed above (Younus and Sreedeep in J Test Eval 40:357–362). The bentonite–sand mixtures are commonly used as a liner material in landfills. As the sand is a scarce material, it is important to find suitable substitutes against the sand. The rock quarry dust is a waste material which can substitute sand to improve the geotechnical properties of soil. In this study, four different B-Q mixtures have been used to determine their compaction and UCS characteristics. The rock quarry dust content varied from 60 to 90%. The UCS values of the mixtures were obtained using the unconfined compression testing machine under two different deformation rates. The results indicated that the maximum dry density (MDD) and UCS value increased significantly when the rock quarry dust content was increased from 60 to 70%. But, the MDD value remained almost constant and the UCS value decreased significantly when the rock quarry dust content was increased from 70 to 90%. The results further revealed that the deformation rate considered has minimum influence on the UCS of the mixtures. Based on the MDD and UCS values obtained, the study recommends an optimum rock quarry dust content of 70% to be added with bentonite to create a cost-effective liner material, especially for landfill applications.