Assessing permanent deformation resistance of high modulus asphalt mixtures

This paper focuses on a case study concerning the evaluation of the mechanical characteristics of high modulus asphalt mixtures (HiMAMs) for base layers, especially with regard to its permanent deformation resistance. This type of mixture has been used successfully for almost two decades in several countries. However, for Portuguese climatic conditions, which are quite severe during summer in terms of pavement temperature, a better understanding of HiMAMs behavior is needed. Because HiMAMs are produced with low penetration (hard) asphalt cement, the writers expected that these mixtures would make an important contribution to reducing rutting in the structural asphalt layers of Portuguese pavements. The 16 km length of the EN14 (Portuguese National Highway 14) rehabilitated near Porto has supported the research described. Slabs extracted from trial sections were submitted to a traffic simulation test (wheel-tracking). Cylindrical specimens compacted by vibrocompression in the laboratory and cores taken from trial sections were submitted to repetitive loading axial tests at three different temperatures. This made it possible to derive several permanent deformation resistance parameters for HiMAMs. The values for these parameters enable prediction expressions to be developed for those characteristics, and these can be useful for designing HiMAMs, based on performance criteria.