The effect of recycled aggregates on the accuracy of the maturity method on vibrated and self-compacting concretes

Abstract

[Abstract:] Fine and coarse recycled aggregate used jointly as partial replacement of natural aggregate is not allowed for structural concrete in many international standards. More studies about it are needed toward more ecofriendly standards. This research studies one important aspect for structural concrete: the influence of recycled aggregate on the accuracy of the maturity method. A total of 7 mixes were studied with two types of reference concretes: vibrated (VC) and self-compacting concrete (SSC). For vibrated concrete, we studied 4 mixes with different partial replacements of recycled aggregates: 0%, 8%, 20% and 31%. For self-compacting concrete, the partial replacements were 0%, 20% and 50% of the total amount of aggregates. We found that, for percentages equal or higher than 20%, the higher is the percentage of recycled aggregate, the higher the activation energy. It was observed that a unique curve “Maturity–Relative strength (S/S∞)” can be used for each type of concrete (SSC or VC) independent of the percentage of recycled aggregate. In addition, we found higher accuracy of the estimations using the hyperbolic equation for the curve “Maturity–S/S∞” than using the exponential equation; applying the hyperbolic approach, less than 3% of the estimations had an error higher than 10%.