Structural Concrete from 100% Recycled Aggregates

In spite of the amount of construction debris produced every year, recycled aggregates are still not commonly used in the concrete industry. A 100% recycled aggregate concrete—RAC—is not yet allowed by technical codes even though it would greatly help reduce the disposal of debris. This paper considers a construction site that can only be reached by small trucks, where concrete production is performed using manual procedures and the transportation of building materials is difficult and expensive. The aim of this research is to establish a mix design for 100% RAC for structural applications. In this context, recycled aggregates are obtained from the debris crushed by a small portable crusher Crunchy©. Based on a series of tests on concrete cubes and cylinders of aggregates originating from different types of debris, it is shown that 100% RAC is also a promising material for structural applications. At the cost of more cement in comparison to standard concrete, RAC from high-strength aggregates (concrete and gres-porcelain tiles) may be used in r.c. structures. Some of its features, such as its low pH value and low compressive strength in the case of clay-originated aggregates, still need to be studied for an optimized mix design. In addition, it is shown that RACs have approximately the same carbon footprint as standard concrete.