Innovations in HMA Performance Testing. John D’Angelo D’Angelo Consulting, LLC [email protected] Canadian User Producer Group for Asphalt Moncton 2009. Materials Testing. The HMA is tested in some fashion to simulate the real world.
Small sample with loading very unlike the real world.
Must be correlated over a narrow range of conditions and material to the real world.
Again must be correlated over a narrow range of conditions and material to the real world.
Developed during SHRP to evaluate mix performance.
Expensive, complicated, difficult to interpret results.
9-19 Identification of SPTs and Protocol Development (Complete)
9-29 Equipment Specification and Development for SPTs (Active)
9-33A Mix Design Manual for Hot Mix Asphalt (Active)
The test can evaluate the rutting and fatigue response of the AC mix.
The equipment is relatively inexpensive and easy to use.
Test results are inputs for the Mechanistic Empirical Pavement Design Guide.
Va = 8%
E* – Dynamic Modulus
Fn – Flow Number (Repeated Load)
Ft – Flow Time (Static Load)
Simulates Traffic Load
Loading – 0.1 sec
Rest – 0.9 sec
Test provides loss of modulus with load repetitions. This is empirically compared to field performance.
Test is time consuming to run and loading relation to the real world questionable.
New push pull test allows fatigue testing in the AMPT with inputs to the VEPCD model.
Indirect Tensile test-
Used for low temperature properties of the mix
Expensive, easy to setup and run.
Use Creep Strain and Strength
Volume of material tested may not be representative
Asphalt mixtures contain aggregate sizes larger than smallest dimension of beam
Main obstacle: the use of smaller size specimens that may not capture overall behavior of pavement
Previous research at University of Minnesota suggested use of simpler test method based on creep tests of thin beams in three-point bending
Thin beams (6.25 x 12.5 x 100mm) can be used to investigate effect of surface aging, microcracking, and compaction on mechanical properties of asphalt pavements