Should durability be a barrier to the use of crushed concrete aggregate in structural concrete?

Applications involving crushed concrete aggregate (CCA), or recycled concrete aggregate (RCA), are growing, as interest continues to increase in the sustainable sourcing of materials. For CCA to be fully used in structural concrete however, it’s influence on the mechanical and durability properties of the resultant concrete is required. The electrical resistivity and water absorption by capillary action of CEM I and CEM III/A concretes were hence investigated to determine the effects on concrete microstructure and water ingress. Findings show that incorporating coarse CCA has generally a detrimental effect on the microstructure and water ingress of structural concrete. However, this can be mostly overcome through the inclusion of GGBS, hence allowing higher proportions of coarse CCA to be incorporated. Limiting the GGBS and coarse CCA content to 50% and 60% respectively is advised, hence minimising the risk of any significant deterioration of mechanical and durability performance. Results suggest that CCA CEM III/A concrete cou