Study on Strength Estimating of Recycled Concrete Based on Rebound Method and Ultrasonic-Rebound Combined Method

In order to test the applicability of the strength curves of rebound method and ultrasonic-rebound combined method of common concrete in estimating the strength of recycled concrete, basis on the C30 recycled concrete specimens with 70% of recycled coarse aggregate replacement are designed, then changing the replacement ratio of recycled coarse aggregate for experimental verification. The results show that It will lead to a large error if using the strength curves of common concrete to estimate the strength of recycled concrete, and the error grows with the growth of the replacement ratio of recycled coarse aggregate. So It is necessary to establish the special purpose strength curves of recycled concrete with the rate of recycled coarse aggregate. Finally, the strength curves of recycled concrete with recycled coarse aggregate are 30%,50%,70% and 100% are given in this test conditions in this paper.