Natural and Accelerated Carbonation in Concrete Associated with Recycled Coarse Aggregate Treated by Air Jigging Technology

Abstract

Recycled coarse aggregates (RCAs) are widely used as a sustainable material in the construction sector. However, the variability of the material is the main factor that limits its use in practice. This paper investigates the effectiveness of RCA selection by an air jigging process in concrete. The performance was assessed with compressive strength and durability indicators from natural and accelerated carbonation tests. The RCA used was provided by two recycling plants. Air jigging technology reduced the mortar and ceramic content in RCA; hence, it increased the strength of the jigged material relative to concrete without air jigged RCA. However, jigging RCA resulted in natural and accelerated carbonation coefficients up to 2.5 times higher than concrete made with natural coarse aggregate. The treatment of RCA by air jigging technology enhanced the properties of concrete, achieving additional benefits compared with nontreated material. Furthermore, the existing models that provide a correlation between accelerated and natural results of carbonation depth and current international standards do not apply to RCA. Therefore, modifications of these models were carried out to enhance the service life prediction of RCA concrete.