Indirect Evaluation of the Compressive Strength of Recycled Aggregate Concrete at Long Ages and after Exposure to Freezing or Elevated Temperatures

The present work is the outcome of two years of investigations for the effect of incorporation of coarse recycled concrete aggregate (RA) in self-compacting high-strength concrete (SCHSC). By destructive and non-destructive methods; the compressive strength for SCHSC mixes with the incorporation of three different proportions of RA has been studied at various ages for up to two years. In addition, the residual compressive strength has been investigated after exposure to freezing-thawing cycles or to elevated temperature and correlations have been proposed between the compressive strength and ultrasonic pulse velocity (UPV). Thus, the compressive strength can be indirectly evaluated by knowing the measuring of the UPV. The hydration level of the adhered mortar attached to the RA and its quality affect the performance of concrete. Meanwhile, SCHSC is one of the best options for raising up the sustainability of concrete.