Evaluation of Commercial and Scrap Tyre Cellular Reinforcement infilled with Demolition Waste for Granular Sub-base of Flexible Pavements: A Sustainable Approach

Nowadays, use of geocell is gaining more importance in pavement industry as it offers improved performance through confinement and tensioned membrane actions. In the recent years, solid waste management seeks greater attention as it poses serious issues related to their disposal, health and environmental hazards. Effective recycling and reuse of these wastes could be a viable and economical approach towards sustainable construction. In this regard, two such wastes (scrap tyres and construction & demolition (C&D) waste) are considered for investigation. The recycled concrete aggregates (RCA) obtained from the C&D waste is used as granular sub-base material and its performance is compared with conventional crushed aggregates (CCA). Scrap tyre is used as cellular reinforcement (recycled tyre cell (RTC)) and its effectiveness as a reinforcing material is compared with the commercial cellular reinforcement (commercially available geocell (CGC)). The study involved construction of laboratory pavement sections under unreinforced and reinforced conditions and testing under repeated loading. The pavement sections supplemented with CGC and RTC reinforcement showed reduced permanent deformation by 27 & 33% and 30 & 35% respectively for CCA and RCA infill materials. The comparable performance of RCA with CCA is attributed to the self-cementation effect offered by the adhered residual cement mortar. With CGC and RTC reinforcement, residual pressure at the subgrade level reduced by 30 and 37% respectively. Provision of cellular reinforcement improved the stress distribution angle than the respective unreinforced pavements and highest improvement is observed in case RTC. Improved behaviour with RTC is due to the increased strip thickness and tensile strength of recycled tyre strip than the ones used in the preparation of CGC. Irrespective of the infill material, higher strains were experienced under the loading zone than the neighbouring cells. Overall, the study promotes use of scrap tyres and RCA in bulk volume for pavement construction offering an eco-friendly, cost-effective, sustainable and long-lasting pavements.