Abstract

Recycled concrete aggregate (RCA) was processed from reinforced concrete edge beams sourced from a demolished bridge. This material replaced different ratios of coarse aggregate in a benchmark concrete. The tensile behavior of the developed concrete mixes was characterized via monotonic and cyclic uniaxial tensile tests performed on notched cylinders. Such tensile tests allow for the quantification of the fracture energy and softening behavior of the concrete. Moreover, acoustic emission (AE) measurements were conducted in conjunction with the cyclic tests to characterize e.g. micro-crack initiation and development, as well as crack localization. The tensile behavior of the various materials was found to be similar with minimal variation in the results. However, the softening behavior suggests that the RCA materials are slightly more brittle compared to both the mother and benchmark materials. The corresponding AE measurements also indicated similarities between the micro-crack initiation and development for these mixes. It can be constituted that if the concrete used to produce RCA is of high quality and from one source, the resulting RAC will have adequate tensile properties with minimal variation, despite the aggregate replacement ratio.

Highlights

  • BackgroundClosed‐loop thinking is paramount concerning the responsible use of concrete as a building material

  • There is no obvious difference in performance between the specimens with differing amounts of Recycled Concrete Aggregates (RCA) replacement and the RCA materials seem comparable to the benchmark material

  • Based on the conducted uniaxial tensile tests, no significant differences in the tensile behavior were noted between the specimens with different amounts of RCA replacement

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Summary

Introduction

Closed‐loop thinking is paramount concerning the responsible use of concrete as a building material. Residual concrete or demolition concrete waste can be crushed and recycled as aggregates and applied in new concrete or as filler material; the result of this being denoted as Recycled Concrete Aggregates (RCA). A promising market has been identified for re‐use aggregates stemming from construction and demolition waste (CDW) in e.g. roads, drainage and other construction projects, but it is projected that the application can be extended to structural applications. The production of CDW in EU is estimated to be around 0.8‐ 1.2 ton/person‐year; all while, the yearly consumption of new aggregates is around 5.1 ton/person [2, 3]. Recycling and re‐use of CDW is supported by the European Commission through the Waste Framework

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