Enhanced washing resistance of photocatalytic exposed aggregate cementitious materials based on g-C3N4 nanosheets-recycled asphalt pavement aggregate composites

Abstract The photocatalytic exposed aggregate cementitious materials (PEACM) have been proposed and successfully utilized for environmental remediation in recent years. In this work, we develop a novel photocatalytic recycled asphalt pavement aggregate (PRAPA), namely g-C3N4 nanosheets-recycled asphalt pavement aggregate composites. The cohesive property of residual asphalt is beneficial to the attachment of g-C3N4 nanosheets (CNNs) on the surface of recycled asphalt pavement aggregate (RAPA) due to a strong bond between CNNs and RAPA. The results show that with a higher concentration of CNNs suspension, the NOx removal efficiency of both the PRAPA and the associated PEACM increases first and then tends to be constant. Compared with the CNNs-standard sand composites and the associated PEACM, the PRAPA and the associated PEACM hold the higher photocatalytic activity and better resistance to rain wash, respectively. The findings of this work provide a new route for preparation of highly cost-effective photocatalytic building materials, and contribute to a desirable option for recycling waste asphalt mixtures.