Estimating the Asphalt Binder Film Thickness Using Scanning Electron Microscope and Energy Dispersive X-Ray Spectroscopy

Table 1

Recommended asphalt binder film thicknesses for HMA.

Film thickness (μm)	Author
8 μm (avg.)	McLeod [13]
8–15 μm	Roberts et al. [1]
9-10 μm (min)	Kandhal et al. [12]
6–8 μm (min) (no background research data is available to support these recommended minimum values)
9-10 μm at 8% air voids	Kandhal and Chakraborty [14]
9-10 (optimum)	Sengoz and Agar [15]
9–15.5 μm (based on index model)	Heitzman [16]
8.5–13.5 μm (based on virtual model)
7.5 μm (min) for minimum fatigue life of 70 k cycles.	Oliver [17]
9 μm for fatigue life of 140 k cycles
Film thickness has to be increased for higher fatigue lives of asphalt
9–11 μm (avg.) for higher stripping resistance of asphalt	AlKofahi and Khedaywi [11]