Evaluating the thermal aging-induced raveling potential of thin friction course (TFC)

Abstract

Thin friction course (TFC) mixed with open-graded aggregate ranging from 3 to 5 mm, styrene-butadiene rubber (SBR)-modified asphalt emulsion, and cement is constructed to improve the skid resistance of underlying pavements and reduce traffic noise. Considering the small thickness (approximately 5 mm) and open gradation of TFC, the mixture is exposed to environmental conditions over its entire thickness. Therefore, the TFC is vulnerable to aging-induced damage, such as aging-induced late raveling distress. This paper aims to determine the aging-induced raveling performance of TFCs, chemical composition transformation, and raveling-related rheological properties of asphalt emulsion residue via a wet track abrasion test (WTAT), transform infrared spectroscopy (FTIR), and a linear amplitude sweep (LAS) test, respectively. Finally, a correlation analysis was conducted. The results indicate that at the initial aging period, prolonging the aging duration could decrease the raveling potential of TFC. However, late raveling may occur when the TFC specimens are aged for 14d, and the aggregate loss increase with the aging duration. Similarly, the enhanced emulsion and SBR dosages are favorable to improve the raveling resistance of TFC and delay the late raveling of TFC. Regarding the chemical transformation, the existence of SBR latex decreases the aging degree. Furthermore, according to the LAS test, the increased SBR latex contents may improve the fatigue resistance of asphalt emulsion residue owing to the spot-welding effects. Finally, the aging degree index SI correlates well with the raveling potential of TFC with a correlation coefficient of 0.71. Typically, the higher the aging degree of asphalt emulsion, the lower the raveling potential of TFC; the greater the fatigue resistance of asphalt emulsion, the lower the raveling potential of TFC.