Durability and performance characteristics of recycled aggregate concrete

In recent years, the recycling of concrete to produce aggregates suitable for nonstructural concrete applications is emerging as a commercially viable and technically feasible operation. In this paper, we report on performance and durability tests carried out to determine the fresh and hardened properties of concrete made with commercially produced coarse recycled concrete aggregate and natural fine sand. Test results indicate that the difference between the characteristics of fresh and hardened recycled aggregate concrete and natural aggregate concrete is relatively narrower than reported for laboratory-crushed recycled aggregate concrete mixes. For concrete without blast furnace slag, having similar volumetric mix proportions and workability, there was no difference at the 5% significance level in concrete compressive and tensile strengths of recycled concrete and control normal concrete made from natural basalt aggregate and fine sand. Water absorption rates and carbonation of recycled concrete and reference concrete were comparable. However, the abrasion loss of recycled aggregate concrete made with ordinary Portland cement increased by about 12% compared to normal concrete, while the corresponding drying shrinkage was about 25% higher at one year. Long-term performance results generated from field case studies involving the construction of a 120 m long bicycle/footpath with a 40 m recycled aggregate concrete (RC) segment are discussed. The paper further discusses observed fresh and hardened concrete properties of both recycled and conventional aggregates, and examines specific implications for satisfactory performance of the recycled product for recreational and non-structural construction applications