Compressive strength assessment of recycled aggregate concrete using Schmidt rebound hammer and core testing

The main objective of this study was to estimate the compressive strength of recycled aggregate concrete (RAC) by means of Schmidt rebound hammer and core testing. The use of recycled aggregate in concrete has been shown to lead to a decrease in the construction cost and it can reduce the burden on the environment by saving natural aggregates. On the other hand, some non-destructive and semi-destructive techniques, such as Schmidt rebound hammer and core testing, are long-established methods for strength estimation of materials. Thus, the present study intended to obtain the compressive strength of RAC using these methods and then compare it with the results of 150 mm cube specimens. To achieve this goal, after producing concrete mixes with 70% replacement of recycled coarse aggregate, 96 cube specimens and 8 concrete slabs were cast to perform Schmidt rebound hammer, core and cube testing. In addition, the combination of the methods was used to obtain correlations between Schmidt rebound hammer and core testing. The results demonstrate that a multi-variable equation using these tests' results can efficiently predict the compressive strength of RAC and conventional concrete and is more promising than single-variable equations based on the Schmidt rebound hammer test results. (C) 2019 Elsevier Ltd. All rights reserved.