Asphalt volumetric properties affecting fatigue cracking prediction

17 days ago by
I have laboratory measured values for the dynamic modulus (E*) of certain asphalt mix. The air voids and effective asphalt content for the specimens used to measure E* were 4% and 9.5%, respectively. These volumetric values (especially air voids) are relatively different than the typical volumetric values obtained for construction specimens (i.e.  Air Voids 7.07% and Effective Asphalt Content 9.47%).  According the MEPDG Manual of Practice, the asphalt volumetric properties entered into the program need to be representative of the mixture after compaction before the pavement is opened to truck traffic. Therefore, I am entering 7.07% for air voids and 9.47%  for effective asphalt content. My concern is that the E* values I have are not representative of construction conditions, and if I use them, I would be mixing up laboratory conditions (for E*) and construction conditions (for volumetric properties).

Should the E* values be remeasured for “construction” conditions, so the cracking prediction is more accurate?

1 Answer

17 days ago by
Yes, the E* values measured in the laboratory should be representative of the in place values after construction to ensure compatibility between the volumetric properties and other engineering properties (dynamic modulus, creep compliance, indirect tensile strength, repeated load plastic deformation coefficients, and fatigue strength or fracture coefficients).
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