VAA Virginia Asphalt Fall/Winter 2021

VAASPHALT.ORG 29 VTRC PROGRAM OVERVIEW FALL 2021 to detect and quantify the presence of microplastics, which might be generated from pavement wear and mobilized via storm-water runoff. Microplastics typi- cally break down from larger plastic pieces and have been found to accumulate in places that can adversely impact aquatic and other terrestrial organisms (includ- ing humans). While RPMA represents a promising way to reuse (and dispose of) plastics, researchers will be working hard to ensure we don’t solve one problem while creating another. The Pavement’s Team will be assisted by the Research Council’s Environmental Research program as Lewis Lloyd assists Jhony to lead this multidisci- plined study. Construction Quality Assurance VDOT and its industry partners have made important progress in recent years with the in-place density of new dense-graded asphalt pavements. Significant contributors to those improvements include both tweaks in mix design criteria and aggressive quality incentives. Despite these positive devel- opments, what we know about compacted quality continues to be extrapolated from very limited, often destructive sampling. The summer of 2021 was an opportunity to begin testing technology that may give us a complete view of the quality of the compacted mat. In late spring, courtesy of another FHWA State Transportation Innovation Council (STIC) grant, VTRC took delivery of a rolling density meter (RDM). The RDM is a ground-penetrating radar (GPR) based system that can quickly and non-destructively conduct continu- ous sweeps of the surface mixes dielectric properties, which have demonstrated strong correlations to in-place voids. Hari Nair and Brian Diefenderfer have conducted testing on several paving proj- ects this year and are making plans to include more work next year. Objectives for this work are to assess a higher per- centage of the surface, which we hope will enable incentives that better recognize and reward uniform compaction—with much less coring! Figure 1 Hybrid Rubber Modified Asphalt (HRMA). (a) Ground Tire Rubber (GTR). (b) Core of HRMA. Figure 2 Types of plastics used in recycle plastic modified asphalt (RPMA). (a) Complex Polyethylene (PE). (b) Polyethylene Terephthalate (PET). Figure 3 Scanning a new asphalt mat with the rolling density meter (RDM).