Compressive behaviour of recycled aggregate concrete under impact loading

The compressive behaviour of recycled aggregate concrete (RAC) with different recycled coarse aggregate (RCA) replacement percentages was experimentally investigated under quasi-static to high strain rate loading. Quasistatic tests at a strain rate of 10-5/s were first carried out using a stiff-framed servo-hydraulic machine. Impacting tests at strain rates ranging from 101/s to 102/s were then performed using a 74 mm-diameter Split Hopkinson Pressure Bar (SHPB) facility. The strain rate effects on the failure pattern, compressive strength, initial elastic modulus and peak strain were studied. The results showed that the compressive strength and initial elastic modulus increased with increasing strain rate while the peak strain did not display clear strain rate dependence. At high strain rates the compressive strength decreased with increasing RCA replacement percentage, whereas the dynamic increase factor (DIF) showed a reverse tendency. Furthermore, the dynamic compressive strength of wet RAC was lower than that of naturally dried RAC.