Modification of Bentonite Clay Using Recycled Glass Powder and Polypropylene Fiber

Expansive soils poses significant challenges in civil engineering projects, yet construction on them in many circumstances is unavoidable. Soil modification, therefore, is one of the finest options for improving the expansive properties of such soils. This study uses commercially available Sodium Bentonite as an expansive soil, where Recycled Glass Powder (RGP) alone and in combination with Polypropylene Fiber (PPF) are used as modifiers. RGP in the percentages of 5%, 10%, 20%, and 30% by dry weight, and 20% RGP in combination with PPF in the proportions of 0.25%, 0.5%, and 1.0% by dry weight of the soil sample were used in the study. Various tests to evaluate the index and engineering properties of both virgin and modified soil samples were carried out, including Atterberg limits, linear shrinkage (LS), specific gravity, compaction, free swelling index (FSI), expansivity index (EI), and one-dimensional consolidation test. Moreover, scanning electron microscopy and zeta-potential test were carried out to analyze the microstructural and electrokinetic properties of modified soil. The results demonstrated a significant decrease in LS (35.43%), FSI (62.23%), EI (50.29%), swelling index (37%), and compression index (22%) with the addition of 30% RGP. Furthermore, incorporating 1% and 0.5% PPF showed a remarkable decrease in LS (50%), and EI (31.78%), respectively as compared to the base soil mix with 20% RGP. Overall, recycled glass powder (RGP) and polypropylene fiber (PPF) as modifying agents hold strong potential for enhancing the expansive and swelling properties of highly expansive bentonite clay, offering promising solutions for construction challenges associated with expansive soils.