Recycled aggregates for self-compacting concrete

Civil Engineering

The protection of natural resources is becoming more and more necessary, at the same time, the demolition of concrete structures generates significant quantities of waste which could be crushed and then recycled in the form of aggregates. Until now, only a small fraction of this waste has been reused, mainly in road works. Improved characterization techniques for recycled concrete aggregates (GBR) and a better understanding of the properties of concretes manufactured with them would promote the use of GBR. This work aims to study the influence of the use of recycled concrete aggregates on the behavior in the fresh and hardening state of mortars for the formulation of self-placing concrete. The results show that the water absorption of recycled concrete aggregates (BGR) is greater than that of natural aggregates (GN). A first part of the work consisted in making the different concrete compositions while a second part is devoted to performance tests, allowing us to qualify the concretes obtained. The compactness of concrete directly influences its porosity, when the porosity increases, the compressive strength of the concrete decreases. However, the addition of limestone filler and superplasticizer gives the recycled aggregate concrete a maneuverability that can be described as self-compacting according to the results of spreading with Abrams cone.

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