Evaluation of premature failures of open-graded friction course pavements in Alabama

Abstract

Open-graded friction courses (OGFC) are special purpose thin surface mixtures used to reduce the risk of hydroplaning, wet skidding, splash and spray, pavement noise, and improve night and wet weather visibility of the pavement markings. The problems hindering the widespread use of OGFC are raveling, bleeding, potholes, and relatively short performance life. As, a prelude to a larger research project to improve durability of OGFC pavement, the performance of five OGFC pavements situated in the state of Alabama, located in the southeastern region of United States, was assessed in detail. The scope of the research involved both field work and lab investigations. Field work involved a field distress survey and coring on the selected projects for forensic investigation. Laboratory investigations included indirect tensile (IDT) strength, air voids, gradation and percentage asphalt content of the extracted cores. X-ray images of the cores were used to analyze the variation of air voids along the depth of OGFC pavement. An analysis of variance test on air void and IDT showed that these parameters can be significant in determining the cause of failure in early ages of the OGFC pavement. The trend of higher IDT values and less air voids in good performing portions as compared to bad performing portions was observed. IDT can be considered as criteria for performance evaluation of OGFC pavements. Granite aggregate appears to be better in resistance against degradation than slag and sandstone. The analysis of air voids along the depth of OGFC projects showed insufficient rate of tack coat or asphalt drain down as important factor leading to bad performance.