A Review of the Characteristics of Recycled Aggregates and the Mechanical Properties of Concrete Produced by Replacing Natural Coarse Aggregates with Recycled Ones—Fostering Resilient and Sustainable Infrastructures

The construction industry is responsible for 50% of mineral resource extraction and 35% of greenhouse gas (GHG) emissions. In this context, concrete stands out as one of the most consumed materials in the world. More than 30 billion tons of this material are produced annually, resulting in the extraction of around 19.4 billion tons of aggregates (mainly sand and gravel) per year. Therefore, it is urgent to develop strategies that aim to minimize the environmental impacts arising from this production chain. Currently, one of the most widely adopted solutions is the production of concrete through the reuse of construction and demolition waste. Thus, the objective of this research is to conduct a systematic literature review (SLR) on the use of recycled aggregates in concrete production, aiming to increase urban resilience by reducing the consumption of natural aggregates. An extensive search was performed in one of the most respected scientific databases (Scopus), and after a careful selection process, the main articles related to the topic were considered eligible through the PRISMA protocol. The selected manuscripts were then subjected to bibliographic and bibliometric analyses, allowing us to reach the state-of-the-art on the subject. The results obtained on the replacement rates of natural aggregate by recycled aggregate indicate that the recommendations vary from 20 to 60%, and these rates may be higher as long as the recycled aggregate is characterized, and may reach up to 100% as long as the matric concrete has a minimum compressive strength of 60 MPa. The specific gravity of most recycled aggregates ranges from 1.91 to 2.70, maintaining an average density of 2.32 g/cm3. Residual mortar adhered to recycled aggregates ranges from 20 to 56%. The water absorption process of recycled aggregate can vary from 2 to 15%. The mechanical strength of mixtures with recycled aggregates is significantly reduced due to the amount of mortar adhered to the aggregates. The use of recycled aggregates results in a compressive strength approximately 2.6 to 43% lower than that of concrete with natural aggregates, depending on the replacement rate. The same behavior was identified in relation to tensile strength. The modulus of elasticity showed a reduction of 25%, and the flexural strength was reduced by up to 15%.