Laboratory Evaluation of Critical Properties and Attributes of Calcined Bauxite and Steel Slag Aggregates for Pavement Friction Surfacing

The long-term friction performance of safety-focused friction surfacing, especially high-friction surface treatment (HFST), relies primarily on the properties of aggregate. Nevertheless, inconsistencies exist in the properties and attributes and requirements for aggregates across the country. A study was conducted to evaluate the properties of the calcined bauxite and steel slag aggregates selected for HFST. Differences were identified between the British Standard (BS) and AASHTO test methods for aggregate abrasion and polishing. Laboratory tests were conducted to determine the mechanical, physical, chemical, and geometric properties of the selected aggregates. It was found that the Micro-Deval abrasion (MDA) test is a repeatable test. A size effect existed in both the abrasion and polishing tests. It was concluded that steel slag may be used as an alternative aggregate for friction surfacing. The requirements for aggregates for HFST were established in terms of the critical property attributes, particularly the Los Angeles abrasion (LAA), MDA, and polish value PV-10, which can be readily implemented by state Departments of Transportation.