Influence of the water variation on the mechanical properties of concrete manufactured with recycled mixed aggregates for pre-stressed components

This work aims to study the influence of water/cement ratio variation on some mechanical properties of concrete made with mixed recycled aggregate when it is used to prefabricate prestressed joists for flooring systems. All natural aggregate was replaced in volume by mixed recycled aggregate that means 50% recycled concrete aggregate and 50% recycled ceramic aggregate. Mixed recycled aggregate includes both, the fine and the coarse fraction. For the different mixtures considered in this research, the volume of water was modified while the mass of aggregates and cement were kept constant. After the curing period, different tests were carried out in order to obtain the most important mechanical properties of these concretes. The results showed a significant decrease of their properties due to the complete substitution of natural aggregates by the recycled material, and because of the water/cement ratio increase.