Investigating Fuel Resistance Characterization Methods of Airfield Asphalt Mixtures: Mass Loss and Mechanical Properties

Abstract

Fuel resistant asphalt (FRA) mixtures have emerged as a viable solution to resist degradation caused by routine fuel spills or oil leaks for airfield pavements. In current specifications for the Federal Aviation Administration and the Department of Defense, fuel resistance is measured by fuel mass loss (FML) after immersion in kerosene for 24 h and drying for 24 h. The literature states this protocol is sufficient to quantify fuel resistance; however, research investigating the sensitivity of fuel resistance test results to varying test parameters is limited. This research investigated fuel resistance characterization methods for FRA mixtures through a detailed assessment of the current fuel immersion test and an assessment of the relative merits of supplemental mechanical property tests. Fuel immersion testing was performed on three FRA mixtures, two conventional polymer-modified airfield asphalt mixtures, and one unmodified mixture. Immersion fluid and time, drying time, and measured parameters for quantifying fuel resistance were assessed. Testing included the traditional method of FML along with mechanical testing, which included the Illinois flexibility index test, disk-shaped compact tension, asphalt pavement analyzer wheel tracking, indirect tensile (IDT) strength, and Cantabro mass loss (CML). Ultimately, FML was found not to be sensitive to all key parameters, suggesting supplementing fuel resistance characterization with mechanical testing, specifically IDT strength or CML, would more clearly distinguish FRA mixtures. While both IDT strength and CML have merit, CML is preferred because of the test mechanisms more closely aligning with the distresses of interest for fuel resistance.