Friction and Snow–Pavement Bond after Salting and Plowing Permeable Friction Surfaces

Abstract

Open graded, ultrathin, and permeable friction course surfaces (collectively referred to as PFSs) have been successfully used by many transportation agencies in several countries as a wearing surface to help reduce water splash and spray, reduce potential for hydroplaning, increase friction, and reduce noise. Despite these advantages, when used in colder climates PFSs tend to freeze more rapidly, transport deicing/anti-icing chemicals from the road surface, clog from sands and other debris, and retain snow and ice for a longer period of time. Most of the reported difficulties with PFSs are at near-freezing temperatures (28°F–35°F). Laboratory tests were conducted using samples of traditional dense graded pavement (DGP), cores from new and old in-service open graded friction course pavements, and ultrathin friction course samples made from hot mix asphalt collected from paving operations. The tests were conducted in a walk-in environmental chamber at 28°F. Snow–pavement bond strength and static friction were measured to determine the effectiveness of anti-icing with salt brine and deicing with dry and pre-wet solid salt. The test results revealed that compacted snow bonds more strongly to PFSs, yet friction of PFSs was significantly greater than DGPs after snow removal, even without the use of salt. The PFSs appeared more white and snowy, and this appearance may be contributing to unnecessarily high application rates of salt by practitioners. Field testing is recommended to better understand the frictional behavior of PFSs during a variety of winter storm conditions and deicer application strategies.