Implementing Circular Economy Strategies for Applications in Construction: Optimizing Cellulose-Based Waste in Building Materials

Integrating wastes in construction and building materials represents a promising possibility to implement circular economy (CE) in construction. This approach, conceived to find a solution to the massive waste generation, is recognized for its sustainability and efficiency as it exploits unused materials as valuable resources for the production of novel building materials. In this context, special attention is given to cellulose fibres, used for their lightweight nature andmechanical strength that can be exploited to improve materials performance for applications in construction. This paper offers an overview on cellulose-based wastes use in construction, exploring characteristics and potential applications. As some relevant examples, cellulose fibres can serve as lightening elements in building blocks and reinforcement in cementitious composites. Moreover, cellulose fibres show a high-energy performance with reduced environmental impact compared to other insulating materials. Furthermore, that significantly contributes to the energy efficiency in buildings. In order to decrease reliance on virgin fibres, three types of cellulose-based wastes are discussed: olive stones (as agricultural waste), waste-paper (as municipal waste), and paper industry by-products (as industrial waste). The analysed residues, that integrate technological innovation and environmental awareness, outline a prospective scenario in which the development of novel constructionmaterials is in line with the environmental standards, following the principles of the CE and energy efficiency strategies. This study is component of two PhD theses focusing on the reutilisation of wastes from various sectors in the field of building materials. More particularly, one of these is developed under the National Recovery and Resilience Plan (PNRR) and is aimed at investigating green solutions to improve the energy efficiency in buildings by valorising and reusing secondary raw materials.