Tests and Simulation of the Bond-Slip between Steel and Concrete with Recycled Aggregates from CDW

This works intends to analyze, experimentally and numerically, the bond-slip behavior between steel and concrete made with recycled aggregates (RA) from construction and demolition waste (CDW) from several recycling plants in Portugal. Pull-out tests performed in concrete mixes with RA from CDW are described and the main results (bond strength, bond-slip curves and failure modes) are shown and discussed. Additionally, a comparison between experimental and analytical (using equations from the literature) results is made. Afterwards, finite element (FE) models using Abaqus are developed and compared with the experimental results. The interface behavior between steel and concrete follows that prescribed by the CEB-FIP Model Code and uses as input experimental results. After validation, the models show good results when extended to predict the bond-slip behavior of the remaining concrete mixes studied. It is generally concluded that, per each 10% of natural aggregates replaced with RA from CDW, the bond strength decreases in circa 3% (numerically) to 5% (experimentally). CEB-FIP Model Code equations are shown to be able to predict bond strength and, when used in FE models, to lead to accurate simulation of the bond-slip response of steel and concrete with RA from CDW: the average ratio between numerical and experimental bond strengths is 0.95. In the scope of the FE models developed, a simple equation to be used along with those prescribed by CEB-FIP, which accounts for fraction and ratio of aggregates replaced, is put forward, as a first approach, showing good results.

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