Consolidation Behaviour of Stone Columns Made with Tyre-Derived Aggregates

Stone columns increase load carrying capacity when constructed in soft soil and help in drainage of pore water from surrounding clay bed. With waste tyres being increasingly used in geotechnical applications, the present study, through model tests, explores feasibility of using shredded tyre chips from scrap tyres as a partial fill material in stone columns constructed as consolidation drain in soft clay. Results reveal a decrease of about 30–50% and 20–30% time required for 90% consolidation (t) with respect to that of pure clay bed and ordinary columns (SOSC-100S), respectively, with construction of geosynthetic encased columns. Marginal variation in t was observed in case of 100S and 70S+30T combinations. Encased columns irrespective of mix-proportion composing the column, leads to lower consolidation time (t). Encased columns with tyre chips content of 30–50% by volume exhibited an appreciably less t. Decrease in t with increase in encasement stiffness up to a certain optimum content of tyre chips was noted. The study concludes that 30–50% of the stone aggregates can be replaced with shredded tyre chips in columns with geosynthetic encasement of proper stiffness. Hence, utilisation of scrap tyres as aggregates in partial proportions in encased stone columns is a sustainable option of effectively reducing the burden of disposal of scrap tyres.