## 7 Future Perspectives and Sustainability Goals
### Circular Business Models and Environmental Assessment  
Circular business models are also essential for advancing the reuse of secondary resources in construction. By creating new value chains, these models turn waste materials into economic assets, providing new revenue streams for industries, like mining and metallurgy, while reducing their environmental footprint. Establishing partnerships across sectors ensures a steady supply of quality secondary materials, enhancing both the economic and the environmental performance [295]. In this frame, and to ensure that the use of secondary materials meets sustainability goals, life cycle assessment (LCA) is an invaluable tool. An LCA evaluates the environmental impacts of using mining waste and industrial by-products compared to traditional raw materials, helping to identify the most sustainable options. This approach allows for optimizing material use, ensuring that the environmental benefits are maximized throughout the lifecycle of construction products [296]. On the other hand, a material flow analysis (MFA) complements the LCA by assessing the movement of secondary resources within the construction sector. An MFA helps identify opportunities for increased recycling and reuse, guiding the efficient allocation of mining and industrial wastes to applications where they provide the greatest environmental benefit. For instance, an MFA can help determine the most effective uses for slags or tailings, optimizing resource use and reducing waste [297]. Adopting these strategies not only addresses the environmental challenges associated with construction but opens new avenues for economic growth and sustainable development.  
Recent LCA studies support the environmental advantages of using secondary materials such as cellulose, mining tailings, and metallurgical slags in construction. For example, insulation materials made from recycled cellulose fibers consistently show lower environmental impacts across categories, such as global warming potential and embodied energy, when compared to conventional insulation, like expanded polystyrene or mineral wool [298]. One study even reported a net carbon benefit of \(-\)210% for cellulose-insulated walls, due to biogenic carbon storage [299]. Similarly, concrete incorporating mining tailings has demonstrated CO2 emissions reductions of over 50% when used in geopolymeric binders, while a partial cement substitution (5-20%) with tailings can avoid up to 72 kg of CO2 per m3 of concrete produced [300]. Regarding slags, replacing 70% of Portland clinker with ground granulated blast furnace slag was found to reduce greenhouse gas emissions by approximately 47.5% [301]. Copper slag used as a supplementary cementitious material in concrete achieved a \(\sim\)12.8% reduction in CO2 emissions compared to conventional concrete [302]. In addition, steel slag used as aggregate does not increase lifecycle emissions and can help preserve natural resources without compromising structural performance. These findings confirm that integrating waste-derived materials not only diverts waste from landfills but significantly lowers the environmental footprint of buildings and infrastructure.