The use of residues of foundry sand (RFS) in asphalt concrete: an alternative for sustainability in paving

In this paper, residues of foundry sand (RFS) originating from: excavation in industrial landfill and from automotive steel industries were tested as aggregate in hot mix asphalt mixtures. These RFS together with the conventional aggregate were physically characterized at the assays: pulverulent material content by weight, obtaining less than 13%; sieve analysis determined the fine granulometry of these materials (according to the aggregate standard); real, apparent and saturated density very close to the mineral aggregate; and the applied images (10 and 40-fold) obtained in an optical stereoscope of the representative fractions of larger and smaller grain sizes, determined a visually uniform and similar between the materials. Then, were made formulations of mixtures of aggregates and RFS, were substitution of the manufactured sand by the residues of 0% (Control mixture), 50 and 100% in weight and were molded cylindrical specimens (CS) by gyratory compaction method, with asphalt binder type CAP 30/45. These CS were tested in the splitting tensile strength assay obtaining values of tensile strength (TS) of the order of 2,0 MPa, for mixtures containing 50% of RFS and of the order of 1,3 MPa in mixtures containing 100% RFS (of two origins); and test of resilience module obtaining average values of the order of: 2500 to 6000 MPa. It was concluded that the RFS has technical viability as an aggregate in flexible pavements.