Tension stiffening approach for interface characterization in recycled aggregate concrete

This study proposes a comprehensive analysis on the structural performance of reinforced Recycled Aggregate Concrete members. Particularly, it summarizes the results of an experimental investigation aimed at analyzing the tension stiffening behavior of normal and high strength class concretes produced with Recycled Concrete Aggregates (RCAs). The mixtures were proportioned in order to achieve 25 and 65 MPa of compressive strength and, moreover, several recycled-to-natural coarse aggregates replacement ratios were considered: 0%, 25% and 50%. The results derived from this type of test furnish a comprehensive analysis on both the steel-to-matrix interaction and the crack formation and propagation on concrete elements as well as distributed cracking mechanisms. Using a finite difference numerical model, the experimental results are used to back-calculate and identify the steel-to-concrete bond slip law. Also, it is an alternative mean of developing the stress-crack-width law for concrete in tension. The results showed that the use of recycled concrete aggregate does not affect the resulting concrete performance and, therefore, the RCAs can be successfully employed, up to the levels analyzed herein, for the production of structural elements made with normal and high strength class concrete mix.