Effect of quality of parent concrete on the mechanical properties of high performance recycled aggregate concrete

This paper presents the experimental results of a study on the effect of quality of parent concrete (PC) on the properties of recycled aggregates (RA) that are derived from them, and on the mechanical properties of high performance recycled aggregate concrete (HPC) when the RAs are used to prepare new concretes. The PC with strength grades ranged from 30 to 100 MPa were crushed to the sizes of that of coarse aggregates (<20 mm), and then they were used to replace natural aggregates (crushed granite) at percentages of 0 and 100%, for producing new HPC mixes. The results indicated that the compressive strength of the HPC prepared with RA derived from 30 and 45MPa PC was lower than that of the designed concrete strength. However, the strength of the HPC prepared with RA derived from 80 and 100 MPa PCs was similar to or slight higher than that of the corresponding natural aggregate concrete. Moreover, for the new concrete prepared with RAs derived from all PC grades, the splitting tensile strength were higher than the control concrete. The results demonstrated that as far as mechanically properties are concerned, PC with higher strength (80 and 100 MPa) can be used to replace 100% natural aggregates for the production of high performance concrete.