Effect of recycled coarse aggregate to damping variation of concrete

Damping properties of recycled aggregate concrete (RAC) at different replacement percentages of recycled coarse aggregates (RCA) were tested by the suspension method. The test results show that the damping ratio of RAC was higher than that of conventional concrete when the compressive strength was similar, while the vibration frequency of RAC was lower than that of conventional concrete. Compared to conventional concrete, the frequency of RAC with 100% RCA reduced by 11% and its damping ratio increased by 17%. The damping variation of RAC is mainly caused by the new ITZ and old ITZ. It can be expressed by the overlay of the damping distributions associated with the two types of ITZs.