Advantages and shortcomings of the utilization of recycled wastes as aggregates in structural concretes

Abstract

Global material resources are quickly being drained by the demands of global economic development. Simultaneously, the environmental impacts of the massive amounts of waste generated globally every year are also growing exponentially. As such, the implementation of waste recycling through its utilization as a component of a construction material, particularly one with a global demand as high as concrete, is a strategy which acts in both planes: material efficiency and waste generation. This paper details the results of a systematic review performed on the scientific literature that concerns the possibility of incorporating recycled wastes as aggregates in structural ordinary Portland cement concretes. The available literature suggests that a reduced number of wastes of recycled origin may, albeit in low quantities, be used in structural OPC concretes. Furthermore, the presence of substances such as glass wastes or alkali-rich cement fragments in recycled aggregates elevates the potential for expansions originated by the occurrence, in these concretes, of the well known phenomenon known as alkali-silica reaction. Moreover, the variety, quantity and the limits to the utilization of these wastes as aggregates in structural concretes all suggest that a massification of the utilization of recycled aggregates in OPC concretes will not take place. The investigation also found that, in light of the evidence showing that the performance of alkali-activated binder concretes is less impacted by the shortcomings of recycled aggregates, recycled wastes may be better suited for reutilization as aggregates in these concrete compositions.