Evaluation of Cold Recycled Asphalt Mixture Treated with Portland Cement as Base-Layer Materials

Highway agencies are using reclaimed asphalt pavement (RAP), particularly cold recycled asphalt mixtures (CRAMs) more than ever before. CRAMs have been also used by a Korean contractor, but it was observed that pavements constructed with this material in the base layer experienced cracks and other distresses on the surface. Thus, an investigation was carried out to find causes and potential improvements. A case study conducted on a substance called Contractor Mix, including asphalt emulsion, acrylate polymer (AP), and portland cement with a significantly high cement to emulsion ratio resulted in undesired brittleness rendering it similar to cement treated RAP mixture. In the present study, Contractor Mix was further evaluated along with a control hot mix asphalt (HMA) and portland cement concrete (PCC). Also, three more CRAMs with different proportions were evaluated with the same ingredients as Contractor Mix. Experimental study was performed by conducting asphalt mixture tests including dynamic modulus, indirect tensile strength, and compressive strength. Finally, performance of pavements constructed with different CRAMs in base layer were predicted using AASHTOWare Pavement ME Design. The simulated results predicted that while pavements of Contractor Mix would experience transverse cracking, those with HMA, PCC, and all other CRAMs would perform satisfactorily under the conditions investigated in the present study