Conclusions

• Cracking in the HMA Overlay: One bottom-up crack was observed during HVS-A) trafficking at the West edge of the TT56 joint. An additional crack at the bottom of HMA overlay may have been detected at the same joint by an embedded strain gauge (TT56-EG8-3); however, no crack was visible on the surface within the proximity of this sensor at the conclusion of trafficking.
• HMA Overlay Strain Distribution: Surface strain gauges showed that the strain distribution in the HMA overlay was dependent on the type of joint (doweled or undoweled) in the PCC layer. A doweled PCC joint resulted in a uniform strain distribution throughout the HMA overlay. An undoweled joint, however, showed a top-down strain distribution with tensile strains at the surface and compressive strains at the bottom of the HMA overlay.
• Temperature Distribution: Internal temperature in the HMA overlay was greater than the ambient temperature due to sunlight exposure on the HMA overlay. The internal temperature in the HMA layer was not uniform with a peak value at the surface of the HMA overlay. The ambient temperature is not warm enough for a long enough period to influence the lower layers of the pavement structure which remain relatively constant throughout measured period.
• Joint Displacement: Joint displacements in the PCC layer was due to both temperature changes and aircraft trafficking. Temperature change showed to have a greater impact on the magnitude of joint displacement compared to trafficking. Additionally, doweled joints had lower joint displacement values compared to undoweled joints.
• HWD Testing: HWD testing showed a decrease in the backcalculated modulus of the HMA overlay at most joints indicating structural deterioration in the HMA overlay throughout the different phases.

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