Models for predicting strength properties of recycled concretes made with non-treated CRCAs: Empirical approach

In this paper, data taken from various literatures were analysed to evaluate relative reductions in mechanical properties of recycled concretes made with coarse recycled concrete aggregates (CRCAs). Of major interest was the influence of parent concretes from which CRCAs are produced. It was found that high quality CRCAs produced from high strength parent concretes of ≥ 50 MPa, generally exhibit no adverse effects on strength properties of the resulting recycled concretes. In contrast, when regular CRCAs produced from parent concretes of low to normal strengths, are employed to prepare recycled concretes, compressive strength loss of up to 30% occurs. Also in the present study, new models are proposed for predicting the compressive strengths, splitting tensile strengths and elastic moduli of recycled concretes made with non - treated CRCAs. Validations of the models using independent data sources from the various literatures gave realistic predictions. The proposed models may be employed to convert standard strength grades of conventional concretes made with natural aggregates to the equivalent grades for recycled concretes made with non - treated CRCAs.