New Eco-Sustainable Construction Materials Derived from Industrial Wastes

“Managing waste is equivalent to addressing the problems of our time”. This phrase resonated throughout the entire PhD period. Waste management is necessary for every industrial activity nowadays, but it begins with awareness of the community and everyone. Over time, this awareness helps us recognise the value of what we have, rather than seeking it elsewhere. Compared to everyday life, this value coincides with what we each realise in hindsight after confronting and managing a long-standing and demanding problem. The research project emerged from the need of local industries to manage their waste, aiming to find potentially feasible applications that could give new life to materials previously considered burdensome both economically and socially. Indeed, the waste treated in this thesis has a high impact, posing a constant challenge for local companies, with whom a close collaboration has been established to meet their needs as effectively as possible. Notably, construction and demolition waste (CDW) from the earthquake that devastated Central Italy in 2016 plays a central role. The study of the CDW, for greater completeness of analysis, also aimed at the study of other types of CDWs coming from different geological and construction contexts. This showed how an accurate characterisation of this material is crucial to understanding its recycling potential and limits. Other waste investigated beyond the CDW included organic resin-based materials, such as wind blade scraps from the management of wind turbine blades that have reached the end of their life cycle. For each type of waste, the scientific and social contexts of recycling are illustrated in detail in the materials section (Chapter 2). Their in-depth characterisation was conducted to explore the best applications in the construction context, investigating both Portland cement (PC) and geopolymer. The latter, was scrutinised for their potential to accommodate a greater volume of waste materials (Ulugöl et al., 2021), to exhibit reduced CO2 emissions compared to traditional ordinary PC (OPC) (Turner & Collins, 2013), and for the demonstrated remarkably high mechanical properties and durability (Wallah & Rangan, 2006). Using of geopolymer has allowed the production of binders with a very high waste content. In this context, both fly ash and volcanic ash were used, demonstrating the enormous potential this type of binder can provide in designing eco-sustainable building materials. The findings (obtained as described in methods Chapter 3), as detailed in the results and discussion section (Chapter 4), shed light on the physical and mechanical properties of cementitious materials, contingent upon the constituents and their respective quantities. The materials produced have reconcile the needs of companies that manage the waste used, with the performance requirements that construction applications demand. Specifically, construction waste has proven to be exploitable for the formation of interlocking brick, while resin-based materials have offered a broad range of applications given their remarkably high mechanical performance. Emphasising the pursuit of market acceptance, the research endeavour to identify materials aligned with its demands. The concluding section (Chapter 5) outlines the key findings of this PhD thesis. Throughout, it keeps in mind economic feasibility, waste content optimisation, and suitability for intended applications. Notably, with a steadfast commitment to sustainability, encompassing social, environmental, and economic considerations, the study's holistic approach underscores its significance in addressing pressing sustainability challenges. In essence, this research stands as a testament to the pivotal role of innovative material technologies in advancing sustainability efforts.