Evaluation of the Asphalt Mixture Design Framework for Airfield Pavements in Illinois

R27-231
The Federal Aviation Administration (FAA) advisory circular AC 150/5100-13 authorized the use of state highway material specifications at nonprimary public-use airports serving aircraft less than 60,000 pounds gross weight. This approval is based on the condition that the safety and life span of these airports will not be adversely affected. The use of highway materials provides the Illinois Department of Transportation (IDOT) with benefits, including cost, expertise, material availability, and sustainability. This study investigated the feasibility of using highway mixes for nonprimary airport pavements. Three classes of mixes were evaluated—namely, IDOT highway mixes, IDOT state airport mixes, and FAA airport mixes. The matrix consisted of 18 mixes: 15 surface and 3 binder mixes. The 15 surface mixes comprised seven laboratory-designed (five highway, two airport) and eight plant-produced mixes (four highway, four airport). All binder mixes were airport mixes and had the same composition and mix design parameters as highway mixes. Mixture performance was evaluated using the Hamburg wheel-tracking test (HWTT) to evaluate rut potential, the Illinois flexibility index test (I-FIT) to assess cracking potential, and the tensile strength ratio (TSR) test to evaluate moisture susceptibility. Performance testing was performed at both air voids of 4% and 7% corresponding to the initial in-place densities of nonprimary airports and highways, respectively. From the HWTT results, highway mixes had lower rut potential than airports mixes. With respect to the TSR test, airport mixes had lower tensile strengths than highway mixes. However, the TSR values (ratio of conditioned to unconditioned tensile strength) were similar for highway and airports mixes. The I-FIT results demonstrated comparable results between highway and airport mixes. Airport mixes had higher and comparable flexibility index for laboratory and plant mixes, respectively. By leveraging highway construction mater