# Use of Mineral Waste for the Production of Artificial Aggregates
## 5 Potential Uses of Waste
### Aggregates Based on Non-Ferrous Metallurgical Waste  
The waste products of non-ferrous metallurgy represent the most chemically diverse group of raw materials. The deployment of these materials in the construction industry is primarily contingent upon environmental considerations. Copper smelting slags have a multitude of applications, including use as aggregates, components of cement composites, and even hydraulic binders. Technical approvals are issued for these types of construction products [92]. A technical approval is a positive technical assessment of a product, stating its suitability for use. The approval body for products used in transport infrastructure engineering is the Road and Bridge Research Institute.  
Moreover, copper slags, due to their mechanical properties (LA = 15-28% and PSV = 44-46, according to [92]) and resistance to polishing, as per PN-EN 1097-8:2020-09, \"Tests for mechanical and physical properties of aggregates\", \"Part 8: Determination of the polished stone value\" [90], can be used in mineral-asphal mixtures, including wearing courses, as an alternative to high-quality natural aggregates (with parameters comparable to basalt aggregate). Copper slag is currently produced by the Glogow and Legnica steelworks, with an annual output of approximately 1 million Mg, nearly all of which is utilized in road construction. In recent years, this material has been widely applied in the construction of the S3, S5, and S6 expressways in western Poland.  
Nickel slags have significant potential in terms of technical properties that are important for construction. Their beneficial effect on concrete properties has been proven when nickel slags are used as an alternative aggregate [93; 94; 95]. Experimental research conducted at the Silesian University of Technology as part of the PBL project [88] demonstrated the suitability of nickel slags as an aggregate for mineral-asphal mixtures. However, due to the limited availability of slag, the possible industrial-scale use of this material will be very localized. In terms of mechanical properties, zinc slags are similar to burnt shale (LA = 40-50%), while their chemical properties are more diverse than those of shale, makingthem more reactive (prone to decomposition). Zinc slags may be a source of heavy metal contamination, which necessitates the individual examination of dumping sites with regard to environmental requirements, due to the leaching of zinc and lead [29; 89]. Zinc slag was first used on a large scale as a filtration layer during the construction of the A4 motorway in Upper Silesia at the end of the 20 th century. However, its large-scale use has become less common in recent years, and its storage and processing often face social resistance due to perceived environmental risks. Recycling this waste currently represents the most significant challenge for materials engineering.  
Nickel smelting slags have significant potential in terms of technical properties relevant to construction [95; 96] but are not economically significant due to their scarce resources.  
Zinc smelting slags are characterized by different chemistries, indicating the need to individually test heaps for environmental hazards (zinc and lead leaching) [40; 97; 98]. Only some of them are used for land levelling, earthworks (embankments), and improved subgrades [99; 100]. Recycling this waste currently poses the greatest challenge for materials engineering.