Evaluation of the Bond Strengths Between Concrete and Reinforcement as a Function of Recycled Concrete Aggregate Replacement Level

To evaluate bond strength, 18 direct pull-out specimens were tested with both No. 13 and No. 19 reinforcing bars and nine full-scale beam specimens were tested with non-confined contact lap splices located at mid-span. Analysis of the test data indicates that replacing more than 50% of coarse natural aggregates results in diminished bond strength over concrete containing only virgin natural aggregates. This result suggests that the existing equation for development and splice length as reported in ACI 318 may require additional modification factors to account for the diminished bond strength when associated with replacement of coarse aggregates with RCA.