Laboratory evaluation of high-friction thin overlays for pavement preservation

Traditional asphalt concrete (AC) and stone matrix asphalt (SMA), which are used as thin asphalt overlays, are common maintenance strategies to enhancing ride quality, skid resistance, and durability. Recently, several studies have used a novel asphalt mixture known as a high-friction thin overlay (HFTO) to improve surface characteristics. However, it remains uncertain whether the laboratory properties of HFTO differ significantly from those of conventional mixtures. This study aims to evaluate the laboratory properties of HFTO mixtures and compare them with those of AC and SMA. Those mixtures with nominal maximum size of 9.5 mm were produced in the laboratory, and performance tests were conducted, including wheel tracking test, low temperature flexural creep test, moisture susceptibility test, Cantabro Abrasion Test, Marshall Test, sand patch test, British pendulum test, and indoor tire-rolling-down test. The results showed that the HFTO exhibited a lower tire/pavement noise than the AC and SMA. Additionally, HFTO had superior high-temperature stability, larger macro texture, and higher skid resistance in comparison to those of AC, but lower than those of SMA. Consequently, HFTO mixtures may be considered a suitable replacement for traditional AC mixtures in regions where skid resistance and noise reduction are concerns.