Consolidation Behavior and Undrained Shear Strength of Soft Soil Reinforced with a Crushed Waste Glass Granular Column

Soft soils are characterized by low bearing capacity, high compressibility, and susceptibility to excessive settlement. Granular columns are commonly used to improve such soils; however, conventional column materials such as sand, gravel, and crushed stone are increasingly depleted. As a sustainable alternative, crushed waste glass (CWG) has been identified as a potential granular column material due to its physical and chemical properties being comparable to those of natural aggregates. Despite this potential, limited studies have investigated how key design parameters, such as penetration ratio (PR) and CWG gradation, affect the consolidation behavior and undrained shear strength of reinforced soft soils. This study evaluates the performance of CWG granular columns installed in soft soil represented by kaolin clay. The floating and end-bearing CWG columns with varying gradations were investigated under undrained and consolidation loading conditions. Consolidation and shear strength responses were assessed to quantify the effect of the PR and CWG gradation on soil performance. The results indicate that the CWG column significantly reduces settlement and soil compressibility while improving drainage characteristics. Among the tested configurations, the end-bearing well-graded CWG column provided the greatest improvement, demonstrating a high reduction in total settlement and fast consolidation due to enhanced vertical drainage. These findings highlight the potential of crushed waste glass as an alternative recycled material for granular column reinforcement in soft soil improvement.