Effect of Recycled Concrete Aggregates on the Concrete Breakout Resistance of Headed Bars Embedded in Slender Structural Elements

Recycled concrete aggregates are potentially interesting for the precast concrete industry as they provide a new use for high-quality waste from its products’ life cycle. In precast concrete structures, it is common to use headed bars in several connection types between structural members. This paper presents the results of experimental tests to investigate the impact of replacing coarse natural aggregates with coarse recycled concrete aggregates in the concrete breakout strength of cast-in headed bars embedded in slender structural elements. Results of 12 tests on 16 mm headed bars embedded in 500 × 200 × 900 mm concrete members with an effective embedment depth of 110 mm are presented. The percentage of replacement of natural aggregates by recycled concrete aggregates was 0%, 30%, and 100%, and the flexural reinforcement ratio of the structural elements varied from 0.5% to 3.5%. The behavior and strength of the tested specimens are discussed, and comparisons with theoretical strength estimates are presented. The results showed that the concrete breakout strength of the headed bars was not affected by the use of recycled concrete aggregates and that the flexural reinforcement ratio significantly impacts the load-carrying capacity of the headed bars as they control the crack widths before failure.

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