A comprehensive review of sustainable use of construction and demolition waste as recycled aggregates in the production of concrete – Properties, mix design and on-site applications
Ana Antunes, Hugo Costa, Ricardo do Carmo, Eduardo Júlio
Abstract
The generation of construction and demolition waste (CDW) is exhibiting a consistent upward trajectory, underscoring the urgency of its recovery. The transformation of this waste stream into secondary raw materials is a solution that enhances sustainability and the circular economy in the construction sector. This study offers practical and adaptable solutions for incorporating recycled aggregates (RA), generated from CDW, as a substitutes for natural aggregates (NA) in concrete production. To achieve this, the properties of 223 concrete mixtures are analysed, and a composition method for recycled aggregate concrete (RAC) is proposed. The literature review focuses on the mechanical properties of cement-based concretes incorporating various types and proportions of RA. Following data collection, an analysis was conducted to identify key parameters influencing compressive strength, flexural strength, and Young’s modulus in concrete, considering factors such as the type, quantity, and granulometry of the incorporated RA. Based on these parameters, a flexible mix-design method for RAC with variable RA proportions is proposed, enabling adaptation to the specific requirements of different applications. Additionally, the potential applications of RA in concrete are discussed. RAC presents a powerful solution for advancing the circular economy in construction, transforming CDW into valuable secondary raw materials. Although compressive strength generally decreases with increasing RA content, it can be reach up 6 % reduction for every 10 % replacement of NA, depending on type and quality of RA. Even so, the incorporation of RA remains a viable option. With high predictive accuracy (R² = 0.96), the RAC mix-design method provides a reliable tool for sustainable rehabilitation practices, reducing environmental impact, and promoting the upcycling of CDW.