Modelling of the adhesion between reclaimed asphalt pavement aggregates and hydrated cement paste

Scanning electron microscope images on concrete incorporating 100% RAP material showed the presence of voids between cement paste and RAP aggregates indicating the poor adhesion between these two constituents. Therefore, the LCPC French model, was used with compressive strength data of different RAP concrete mixes to determine the adhesion and threshold parameters of the model. It was found that the adhesion parameter decreases as the RAP content increases while the threshold parameter remained constant for all RAP contents. The model with its described procedure could be used to proportion RAP concretes for any targeted compressive strength.