Characterization of Aggregate Susceptibility to Polishing Using the Micro-Deval Test

Abstract

Skid resistance is a critical pavement surface property affecting roadway safety, especially under wet weather conditions. This study evaluated the frictional characteristics of a wide variety of aggregates used in roadway construction in Ohio. The micro-Deval test was used to apply different levels of polishing (0, 60, 180, and 360 min) to each aggregate material, and the frictional properties of the unpolished and polished aggregates were evaluated using a British pendulum tester (BPT) and a dynamic friction tester (DFT). Texture and angularity of the unpolished and polished aggregates were also evaluated using the second-generation Aggregate Image Measurement System (AIMS2). Carbonate aggregates were generally found to exhibit higher initial friction than natural gravels, but some carbonate aggregates provided poor friction retention after polishing. Slag aggregates were found to have high initial friction properties and good friction retention, while the trap rock used in this study exhibited relatively low initial friction and poor friction retention. It was found in this study that mass loss after abrasion in the micro-Deval test is not a good indicator of the aggregate’s resistance to polishing. Some aggregates exhibited high mass loss but maintained high friction properties, while others showed low mass loss and poor friction retention. The AIMS2 texture was also found to have a relatively low correlation with direct contact friction measurements obtained using the BPT and the DFT. These findings confirm the need for direct contact friction measurements to properly characterize aggregate susceptibility to polishing.