Behavior of recycled aggregates treated with cement paste with respect to capillary absorption and flexion

Abstract

Recycling waste from destroyed structure as a new resource of aggregates has several technical, economic and environmental advantages although it should be noted that these aggregates have disadvantages which can reduce the mechanical concrete properties, one of the most important is the water absorption problem. The waste valorisation industry stands as an alternative solution, effectively managing waste while also preserving natural resources. In this context, the present study consists to recover waste resulting from demolition of old Sonalgaz (Electrical poles) columns built in 1947 in the wilaya of Mostaganem. The obtained aggregates are enveloped by the old cement paste, which is known for its porous nature, resulting in a significant water absorption capacity. For that purpose, it was advisable to determine the required absorbed water quantity to saturate a specific recycled aggregates (RA) volume. In this work, we have opted for the method of cement paste treatment of the aggregates 3/8 mm and 8/16 mm. This method involves covering them by a film of cement paste and letting them dry for 28 days. Additionally, this study includes an analysis of the physical properties of natural and recycled aggregates, both before and after treatment, along with their impact on the mechanical properties of concrete mixes containing fully pre-saturated aggregates (100% RA) and a blend of half recycled and half natural aggregates (50% RA + 50% NA). These results are compared to reference concrete made solely with 100% natural aggregates (NA).