**Abstract**

The environmental issue has become a topic of relevant discussion in modern society, given the current awareness that construction inputs are finite, and a large amount of waste can be reused as a building material in engineering works. The products used in foundry industry can be non ferrous and ferrous and the residue produced by this last one is not potentially hazardous to human health. The waste foundry sand (WFS) fits this reuse and can be employed in asphalt mixtures, in partial or complete replacement of the conventional filler, i.e. Portland cement (PC). In this sense, this work analyses five asphalt mixtures, one using 100% CP (reference mixture) as filler, and the other four using WFS in proportions of 25-100%, every 25% of the total amount, in 5% (in mass) of the maximum replacement. The mixtures were physically and mechanically characterised according to the Marshall methodology and subsequently submitted to the tests of static indirect tensile strength (static ITS), resilient modulus (RM), repeated-load indirect fatigue (fatigue life) and unconfined static creep. The results of the tests showed that all mixtures with WFS residue presented physical and mechanical parameters within Brazilian standards following the Marshall methodology.

**Keywords:** waste foundry sand (WFS), mineral filler, asphalt mixture, fatigue life, static creep, resilient modulus, static indirect tensile strength, Marshall stability

### **1. Introduction**

Industries annually generate millions of metric tons of solid by-products, and most of these materials have been landfilled at considerable cost since. Modern society has been developing beneficial reuse of industrial by-products in a variety of applications [1–3]. Recycling of waste construction materials saves natural resources, saves energy, reduces solid waste, reduces air and water pollutants and reduces greenhouse gases [4, 5]. The transportation, construction and environmental industries have the greatest potential for reuse because they use vast quantities of earthen materials annually. Replacement of natural soils, aggregates and cements with solid industrial by-products is highly desirable [1, 2].

The steel industry produces a myriad of metal components for industrial chains such as the automobile industry, which in turn generates mineral discarded sand moulds (waste foundry sand/WFS) that end up occupying large volumes in

landfills [6]. The major portion of the WFS is considered as non-hazardous waste and is currently deposited in a special WFS landfill that is remote from areas of settlement [7–10].

The metal casting industry annually discards about 10% of foundry sand for production, i.e. approximately an estimated 9–10 million tons of WFS each year, in the USA [5, 10, 11]. Generally speaking, approximately 1 ton of foundry sand is needed to produce 1 ton of metal casting [8, 12]. WFS can be used as an alternative material (fine aggregate in asphalt mixtures) in highway constructions allowing the increasing of the lifespan of landfills [13].

This work analyses the physical and mechanical behaviour of asphalt mixtures, using the WFS as a mineral filler in asphalt concrete, in 5% (in mass) of maximum replacement to conventional Portland cement (CP). The waste was obtained from an industry located in the free-trade zone of Manaus city, Amazon State, Brazil. The results showed that the addition of industrial WFS in asphalt mixture resulted in adequate performance of the mixtures.
