Performance Evaluation of Natural and Recycled Aggregates in Stone Columns: A Sustainable Ground Improvement Approach

Ground improvement techniques effectively use stone columns to increase the load-bearing capacity of soft soils. The characteristics of the filler material significantly influence its performance. This study presents the performance evaluation of three different aggregates as filler materials for stone columns: natural crushed aggregates (CA), river aggregates (RA), and recycled construction and demolition waste aggregates (RCDW). Using these fillers, laboratory experiments on soft soil reinforced with a single stone column of diameter 25 mm were conducted in different cylindrical moulds prepared using the unit cell concept for spacing to diameter ratios of 2, 2.5, and 3. Pressure–settlement curves were plotted for unreinforced and reinforced soil, and the load-bearing capacities were compared for each stone column filler material. Results revealed that under identical test conditions, the load-bearing capacity of RA was 4% and 44% superior to CA and RCDW, respectively. The performance of RCDW was lowest among the filler materials. However, when encased with geogrid, RCDW showed 5% and 10% better performance comparad to RA and CA, respectively. This research aims to contribute to the utilization of waste aggregates and promote sustainable construction practices. The utilization of encased waste aggregates as stone column filler, especially in the regions where the natural aggregates are scarce or costly, will be a doable solution to successful ground improvement, offering both environmental sustainability and economic advantages.