Valorization of waste foundry sand aggregates in hot-mix asphalt

Abstract

Metal smelting generates a significant volume of industrial solid waste foundry sand (WFS). Although several standards and studies have established practices and requirements for its use, a large portion of the disposed WFS goes to industrial landfills. This study aims to evaluate the value of WFS as an aggregate in hot-mix asphalt mixtures (HMA) using systematic criteria for classification, potentialities, waste generated and applicability. To this end, molding sand (MS) and fine dust of exhaustion (FDE) were characterized, to identify their potential for application as aggregates in asphalt mass. Different contents of MS, FDE, and Blend (BL) were studied according to the normative granulometric ranges of aggregates for HMA. Samples were obtained via the Marshall method to verify important properties for the asphalt mix. Ecotoxicity tests were conducted. The results showed that a composition containing 10 wt% of BL presented an air void volume of 3.3%, a stability of 658 kgf, creep of 2.5 mm, and an indirect tensile strength of 0.93 MPa. From a technical and environmental perspective, a 10 wt% BL content was suitable for recovery into HMA. Lower amounts BL yielded results outside the normative limits. WFS can be recovered and applied as a raw material in HMA.