AASHTO TP 141-20

This test method covers the determination of cracking resistance of asphalt mixtures using the indirect tensile (IDT) geometry at 25°C. The Toughness (area beneath the stress-estimated strain data) and Brittleness Slope (post peak stress-estimated strain rate) are used to calculate a parameter referred to as the Nflex factor, which may be a useful indicator of load-related cracking of asphalt pavement layers.

This procedure applies to test specimens having a nominal maximum aggregate size (NMAS) of 19 mm or less. Lab compacted specimens or field core specimens can be used.