A case study on utilization of 50-year-old concrete in recycled aggregate

This paper investigates some mechanical properties of recycled aggregate concrete (RAC) with 50-year-old recycled coarse aggregate (RCA), and theoretically analyzes the corresponding RAC stress-strain curves relative to those of normal aggregate concrete. Concrete prism specimens, including 66 standard prisms and 33 nonstandard ones, were fabricated and tested through 11 groups of RCA replacement ratios from 0% to 100% with an interval of 10%. On this basis, the standard prism compressive strength at ages of 28 days and two years, the flexural strength of the nonstandard prism, the cube strength after flexural test and the strain at the maximum standard prism compressive stress for 28 days, as well as Poisson’s ratio of the standard prisms for two years was investigated. Finally, analytical expressions were proposed for predicting the peak strain, the stress-strain curves of RAC and the strength conversion relationships.