Sampling for Quality: A Comparison of Sampling Locations for Asphalt Paving Mixtures

Each year, more than 25 percent of highway fatalities in the United States occur at or near horizontal curves, according to the Federal Highway Administration (FHWA). In an attempt to save lives and prevent injuries, some 30 states across the U.S. are applying high friction surfaces (HFS) to improve skid resistance at locations with a high incident of vehicle crashes such as severe horizontal curves, steep grades, roadway intersections, railroad crossings, and crosswalks. As roadway surfaces polish, available pavement friction is reduced. High friction surfaces provide improved skid resistance, and maintaining an appropriate amount of pavement friction is critical for safe driving. High friction surfaces are pavement treatments with high skid-resistant properties not typically provided by conventional materials. Through sitespecific application, a thin layer of high quality, durable aggregates is bonded to the existing pavement surface with a liquid polymer resin binder, restoring and maintaining pavement friction in areas where safe pavement surface properties are critical. These aggregate systems provide a life-saving technology customizable to specific state and local safety needs. The most commonly specified aggregate component of HFS is calcined bauxite, an aluminum ore that increases in physical hardness and stability when heated to a high temperature. Used primarily because it resists polishing, calcined bauxite retains its friction values and properties after years of wear. This aggregate is narrowly graded, passing #4 sieve and retained on #16 sieve. Aggregates must be clean and uniform in size for best results.