Impact evaluation of polypropylene fibres on the engineering behaviour of Siwalik clay

Abstract

In the Kashmir region of Pakistan, the presence of Siwalik Clays engenders serviceability issues to the infrastructure causing substantial loss of property. In the present study, an attempt has been made to address these issues using polypropylene fibers as a sustainable modifier. These fibers were used in five different proportions viz. 0.25%, 0.5%, 0.75%, 1%, and 1.25% as partial replacement of base soil to analyses their impact on the engineering behavior of matrices. Classification, compaction, indirect tensile, unconfined & triaxial compression, swell potential, consolidation, and California bearing ratio tests were performed on controlled as well as reinforced clay samples for comparative analyses. The maximum improvements were observed in unconfined compressive strength (109%); tensile strength (300%); cohesion (13%); friction angle (110%); soaked CBR (800%); and un-soaked CBR (550%). Besides, the reduction in swelling strain by 92% was also recorded corresponding to 1kPa effective vertical stress. The capital cost analyses showed that Polypropylene fibers reduced the costs of backfill behind the retaining wall and foundation soil beneath isolated footing by 21% and 44.5%, respectively. Moreover, the modifier had no adverse effect on the aqueous media. Conclusively, polypropylene fibers can be used as sustainable modifier leading to a potential solution for serviceability issues.