Upcycling of waste concrete in eco-friendly strain-hardening cementitious composites: Mixture design, structural performance, and life-cycle assessment

Abstract

To upcycle waste concrete through producing strain-hardening cementitious composites (SHCC) for sustainable and resilient structures, this research investigates the effect of fine recycled concrete powder on the fresh and hardened properties, optimizes the mixture design, evaluates the structural behavior, and assesses the life-cycle performance of SHCC at material and structural levels. The investigated fresh and hardened properties include the flowability, compressive strength, tensile strength, and ductility. Four full-scale beams, including a conventional reinforced concrete beam and three reinforced SHCC beams with the optimal SHCC mixture, were tested under flexural loads until failure. Life-cycle performance of SHCC was assessed regarding the cost and carbon footprint. The results showed that appropriate use of recycled concrete powder increased the ductility while retaining the adequate compressive and tensile strengths as well as flowability of SHCC. The use of the developed SHCC with recycled concrete powder increased the load capacity and crack resistance of the full-scale reinforced beams. The developed SHCC involves higher upfront cost and carbon footprint but lower life-cycle cost and carbon footprint for the investigated structural beam applications when the service life is longer than 40 years.