# Application of Foundry Wastes in Eco-Efficient Construction Materials: A Review
## 5 Valorization of Foundry Waste in Construction Materials
### Electric Arc Furnace Dust (EAFD)  
Electric arc furnace dust (EAFD) is generated as a byproduct during the steel manufacturing process in an electric arc furnace. This dust forms as a fine material that constitutes most of the fumes or gases emitted by the furnace. The produced dust is extracted through cooling pipes and captured by bag filters specially designed for this task. EAFD is mainly composed of iron oxide (about 50%) and zinc oxide (approximately 21%). EAFD can be considered a toxic substance and should be disposed of after stabilization to prevent the leaching of heavy metals [94]. The use of EAFD in materials such as concrete and mortar is shown next. [PERSON] et al. [95] investigated the application of EAFD as a replacement for silica filler in varying proportions to produce self-compacting mortars (SCM). The objective was to evaluate the mechanical and leaching properties of SCM containing EAFD, with a view to supporting sustainable waste management practices within the framework of the circular economy. The study concluded that EAFD can be used as a replacement material in SCM, with the ideal replacement percentage being 25%, to preserve mechanical and durability properties. In another study, [PERSON] et al. [96] investigated the feasibility of using EAFD as a filler in SCM, with an emphasis on the durability and performance properties of the produced material. Two distinct categories of EAFD, considered hazardous waste, were used. The silica filler was also replaced by EAFD in different contents. The use of SCM containing up to 25% EAFD resulted in compressive strength similar to that of the reference mortar, while higher contents significantly decreased its strength. Moreover, a higher concentration of EAFD resulted in an increased carbonation depth, which can compromise the durability of the mortar. [PERSON] et al. [97] conducted a study to examine the effects of incorporating alkalis (sodium hydroxide--NaOH) in cement pastes and mortars containing EAFD, with the aim of improving setting time and mechanical properties. In this study, the cement was  
Figure 12: Content percentage of slags in SCM and concrete. partially replaced by different amounts of EAFD. It was concluded that the mortars can efficiently incorporate up to 20% of EAFD, with the controlled addition of NaOH, to regulate setting times and initial strength development. Although the inclusion of alkalis accelerates the development of initial resistance, it can also reduce long-term resistance, making it necessary to consider this balance in practical applications. [PERSON] et al. [98] evaluated the effectiveness of an ideal amount of EAFD in a cement-based mixture (mortars) and compared it with conventional supplementary cementitious materials, such as silica fume (SF) and fly ash. (FA). The main objective was to understand the impact of EAFD on the mechanical and physical properties of mortars, both in the fresh and hardened states. A portion of the cement was replaced with 0.5-5% EAFD. The study concluded that EAFD significantly prolongs the setting time of cement pastes due to the presence of zinc. The ideal EAFD content exhibited a compressive strength like that of FA and SF under certain conditions. It was concluded that EAFD can be efficiently used as a partial substitute for cement, with an ideal proportion of around 3%. The use of EAFD as a substitute for cement in conventional concrete was investigated by [PERSON] et al. [99]. The objective was to address the environmental issues related to the disposal of EAFD while improving the mechanical and durability properties of concrete. According to the study results, replacing 2% of the cement with EAFD is ideal for increasing the durability and strength of the concrete. Moreover, the incorporation of EAFD into concrete improved its properties and helped in the management of hazardous waste, contributing to the circular economy.