Strength and Durability Assessment of Dolomite Mine Overburden for Ground Improvement

Dolomite powder in calcined form is conventionally used to stabilize clayey soils. Dolomite overburden is waste generated from the top layers of dolomite mines. This research investigates the geotechnical (Atterberg limits, compaction, California bearing ratio and unconfined compressive strength) and durability (wet and dry cycles) comparison of clayey soil modified with calcined dolomite powder (CDP) and calcined dolomite overburden (CDO). The CDP/CDO was used in the range of 3, 6, 9 and 12% in addition to the dry weight of the soil. Both additives resulted in notable improvement in geotechnical characteristics at lower dosage levels. At higher levels, the improvement in properties became stagnant. The California bearing ratio (CBR) and unconfined compressive strength (UCS) test values suggest minimal difference in the results obtained at 6% CDP and 9% CDO additive content. With the increase in curing time, enhanced durability through wet and dry cycles was observed. The improvement in durability perspective was confirmed by reduced weight loss and improved retained UCS of the CDP/CDO-modified specimens. Based on the experimental results, the microstructural analysis was conducted on 6% CDP-modified and 9% CDO-modified specimens. SEM analysis indicated the dense nature of CDP/CDO-modified specimens. XRD test results showed higher CSH gel peaks and FTIR test results showed marginal higher CSH bond strength in the CDP-modified specimen than the CDO-modified specimen. It was concluded that CDO at higher dosage levels than CDP can be used as an alternative additive in ground improvement applications.