Growing environmental concerns, governmental support and changes in thinking motivate people to focus on more sustainable businesses and to promote new regulations incorporating the principles of sustainability, especially in materials recycling. The main efforts should be devoted to waste reduction and long-term value creation to materials where the key role is attributed to designing for recycling, remanufacturing and reuse, disassembly and sorting, and for the environment.
Stronger regulations on pollution and energy efficiency are working as a driving force for faster changes in production towards the compromise between the goals of environment and economics. Substitution of primary raw materials with secondary ones may significantly diminish the need for virgin raw materials usually obtainable from ore mining. Use of various waste materials such as fly ash from the energy industry, palm-oil fuel ash, natural fibers, alum waste, etc. for soil stabilization is tested and described in the literature.
The approach based on circular economy principles requires eco-efficient and economic solutions in geotechnical engineering. However, the choice on-site should be based on an analysis of the industrial loop and accessibility of secondary raw materials from local industries. The main groups of secondary raw materials include thermally treated waste materials and industrial waste – it will be discussed in the coming scientific publication.
Regarding terminology, some waste materials can be categorized as by-products, however, due to specific criteria set by the legislation in the European Union that have to be fulfilled (Directive 2008/98/EC), it is problematic to use the term ‘by-products’, thus, all secondary raw materials mainly are assessed as a waste.