Recycled concrete aggregates (RCA) and lightweight aggregates (LWA) are popular alternative aggregates for concrete. However, due to their highly porous structure, concrete with RCA and LWA shows a different microstructure and higher permeability than conventional concrete. Thus, the existing relationships used to evaluate the permeability and, consequently, the durability of concrete are not applicable in concretes with RCA and LWA. This research examined the permeation properties of recycled aggregate concrete (RAC) and lightweight aggregate concrete (LWAC). The relationships between electrical resistivity-based measurements in RAC and LWAC and their permeation properties were determined and compared to that of normal weight aggregate concrete (NWAC). At the same electrical resistivity, RAC has higher chloride permeability than LWAC and NWAC. But at the same formation factor, LWAC has higher water permeability than RAC and NWAC. Permeability prediction models for RAC and LWAC were generated using multiple linear regression. Lastly, image analysis was used to determine the air void structure and material composition of the concretes. The air void structure and paste content were found to have significant effects on most permeability measurements
