Tire derived aggregates as a supplementary material with recycled demolition concrete for pavement applications

Waste tires are a non-biodegradable material, which are currently accumulating in stockpiles. The current end-of-life tire recycling rate is only nominal and the primary usage of waste tyres for energy production imposes environmental and health concerns. Increasing production of solid waste from demolition activities also contributes to another stream of waste materials directed for landfills. In this research, an extensive laboratory evaluation was undertaken to determine the engineering properties of recycled concrete aggregates (RCA) blended with tire derived aggregates (TDA). The RCA-TDA blends were evaluated to assess their geotechnical suitability for construction of pavement subbases. RCA was blended with 1%, 2% and 3% (by weight) of 3 different sizes of TDA, to target their usage in pavement subbase applications. The geotechnical characterization of the RCA-TDA blends included particle size distribution, pH, plasticity index, foreign materials content, modified Proctor compaction, California bearing ratio and Repeated Load Triaxial tests including the measurement of resilient deformation. The geotechnical properties of the RCA-TDA blends indicated their suitability in pavement applications. The advanced experimental permanent resilient deformation under repetitive loading and resilient modulus of the RCA-TDA blends also confirmed the viability of using supplementary amounts of TDA in pavement subbase applications. The usage of even small percentage of TDA will divert relatively large amount of these waste materials from landfills and into sustainable pavement construction. (C) 2019 Elsevier Ltd. All rights reserved.