LCA applied to comparative environmental evaluation of aggregate production from recycled waste materials and virgin sources.

Nowadays, all productive sectors, including the construction industry, are facing the challenge of reducing their environmental impact. To achieve this objective, numerous actions are being carried out to access greater levels of environmental and economic sustainability. Techniques as Life Cycle Assessment contribute to quantifying environmental impacts, promoting a circular economy in a sector that consumes a high volume of resources, materials, and energy while generating large amounts of gaseous, liquid, or solid emissions. The present study aims to deepen our understanding of aspects that demonstrate the benefits of using RA instead of natural aggregates. This study not only quantifies the environmental impact but also explores the effects of potential improvements in the productive system and their impact on reducing environmental harm. The Life Cycle Assessment methodology is applied to quantify and compare the environmental impacts generated in the production of a ton of mixed recycled aggregates (MRA) from construction and demolition wastes, based on the data provided by plant managers. This is compared to the environmental impacts generated in the production of one ton of natural aggregates extracted from a quarry. The results revealed that the production of mixed recycled aggregate is more environmentally beneficial, confirming a reduction of 70.66% in environmental impacts during the production of recycled aggregates, in comparison to the natural aggregates extraction. Furthermore, the economic analysis demonstrates the economic advantage since the cost of producing recycled aggregates is over 30% cheaper than natural aggregates, being more competitive even when the transportation distances from the plant to the work sites exceed those of natural aggregates.

Impact of Recycled Aggregate on the Mechanical and Environmental Properties of Concrete: A Review.

This review aims to present and discuss the mechanical and environmental properties of two different type of recycled aggregates obtain from construction and demolition waste (CDW): (1) Recycled Concrete Aggregates (RCA) and (2) Mixed Recycled Aggregates (MRA). In addition, the properties of the concrete in the fresh (workability, water/cement ratio) and hardened state (mechanical and durability properties), as well as the environmental impact of the concrete produced with the two types of recycled aggregates, are presented and discussed. Due to the heterogeneous composition of recycled aggregates, the concrete properties can be significantly variable. The systematic review concerns scientific papers published from 2010 to 2020 and it shows the importance of the selection process in order to obtain high quality CDW as well as of the type of recycled aggregates on concrete properties. In particular, recycled concrete aggregates show a better quality and homogeneity than mixed recycled aggregates that make them more suitable for concrete. This work presents an overview on the influence of recycled aggregate quality on the physical, mechanical and environmental properties of concrete.