Optimizing performances of recycled aggregates for improving concrete properties

Construction waste management is a quite important economic and environmental deal for our societies. More than 2 million tons demolition and construction wastes are annually produced only in Wallonia, Southern Region of Belgium: recycling has clearly to be promoted and by products to be valorised as secondary raw materials.
The influence of the fine recycled concrete aggregates (FRCA) on the mechanical and durability properties of concrete was used for producing concrete. Concretes with different substitution rates (0, 30 and 100%) of natural sand by the FRCA were manufactured. Mechanical properties (compressive strength) and durability properties (capillary absorption, carbonation depth, and freeze/thaw resistance) were investigated. The results show that the compressive strength of concrete decreased as the substitution of FRCA increased. Durability of concrete could be strongly influenced by the high porosity and water absorption of fine recycled concrete aggregates. Brick fillers (BF) have also been studied for producing Self Compacting Mortars (SCM): introduction of 50 and 100% substitution clearly show a reduction of workability properties if particles water absorption is not taken into account. However, mechanical properties at 7 and 28 days didn’t show a clear impact of the substitution of limestone filler by brick filler.