# Application of Foundry Wastes in Eco-Efficient Construction Materials: A Review
## 5 Valorization of Foundry Waste in Construction Materials
### Foundry Slag  
The study of foundry slags can be divided into three main areas: the use of slag as a construction material, the extraction of metals from slag, and the use of slag for environmental remediation. The studies, often focused on ferrous slags, predominantly evaluate the geotechnical properties of the slag from the perspective of engineering and construction. Historically, slags have been widely used as construction materials and continue to see increasing application in environmental contexts ([PERSON] et al., 2017). The increase in cement demand has  
Figure 11: Content percentage of WFS in concrete and bricks. been effectively addressed by slag and other byproducts in cement production, which incurs reduced costs, exploitation of natural resources, and environmental issues. Specifically, ground granulated blast furnace slag (GGBFS), with its unique characteristics acquired through rapid cooling by immersion in water, takes on a vitreous and granular form, making it an excellent material for the production of Portland cement [83]. The following will present studies that investigate the valorization of different types of foundry slags in construction materials. The researchers [PERSON] and [PERSON] [84] analyzed potential applications of steel slag in construction materials. Their findings suggest that steel slag, due to its mechanical and physical characteristics, is well-suited for use as an aggregate in pavement. However, its application is predominantly limited to road construction rather than as fill material under structures, due to the presence of unbound calcium and magnesium, which can cause significant expansion. The study further concludes that steel slag is a highly versatile material, suitable for various construction applications, including the production of concrete, bricks, lightweight aggregates, ceramics, and refractory products. Additionally, it highlights that the level of chromium leaching from concrete mixtures containing slag aggregates falls within the acceptable limits defined by regulatory guidelines. [PERSON] et al. [85] investigated the environmental impact and performance of mortars with the incorporation of waste from the steel and iron industry, namely steel slag and GGBFS. It was determined that with an increase in replacement, greater uniformity and longer setting times were achieved, which delayed the appearance of shrinkage cracks. Due to the hydraulic characteristics of the slag, the compressive strength after 28 days was equivalent to the reference mix, despite the initial loss of strength. The microstructure of the developed mortars showed lower water absorption and greater resistance to sulfuric acid attack, due to their density and lower number of voids. The supplementation with steel slag also increased the electrical resistivity of the mortars and the resistance to carbonation, indicating advantages in terms of performance and durability. [PERSON] and [PERSON] [86] conducted a study to investigate the impact of replacing cement with different proportions of induction furnace slag (IFS) on the physical properties, mechanical properties, and durability of concrete. Their findings indicated that using IFS as a partial substitute for cement can improve the durability of concrete. The ideal level of IFS substitution was 25%, with higher levels of IFS resulting in a decrease in compressive strength and an increase in porosity. The use of ferrous slag as fine aggregate was investigated by [PERSON] et al. [87] to determine the feasibility and potential advantages of adding this waste into various concrete compositions, while also assessing the durability of the concrete. Additionally, different physical and mechanical properties were also evaluated. The study revealed that the compositions that included the slag enhanced the durability and the mechanical performance of the concrete compared to the control with ordinary cement. However, the accelerated alkali-silica test showed possible reactivity, indicating that it is not suitable for use in cement-based materials.