Using the Simple Punching Shear Test (SPST) for evaluating the HMA shear properties and predicting field rutting performance
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2019 Elsevier Ltd The work presented in this paper was conducted to evaluate and validate the Simple Punching Shear Test (SPST) in characterizing the HMA shear properties for rutting performance prediction. The scope of work included SPST sensitivity evaluation in the laboratory with respect to test temperature and HMA mix-design volumetric variables such as the asphalt-binder type and asphalt-binder content, respectively. The corresponding laboratory test results were then validated against field performance data through correlations of the measured HMA shear properties (shear strength) to actual rutting measured in the field. Based on extensive laboratory testing of commonly used Texas coarse-, dense-, and fine-graded mixes (with different mix-design characteristics/combinations), it was found that the SPST is reasonably sensitive to test temperatures and the HMA mix-design volumetric parameters that were investigated in the study. The HMA shear strength generally exhibited a decreasing trend with an increase in the test temperature and asphalt-binder content, respectively. However, as the Performance Grade (PG) of the asphalt-binder increased, so did the HMA shear strength. With respect to SPST field validation, the HMA shear strength measured from the SPST correlated well with the field HMA rutting performance, exhibiting higher rutting resistance (i.e., low rut depths) for mixes with higher HMA shear strength and vice versa. Overall, based on the study findings, the SPST was found to be a viable surrogate laboratory test method for routinely measuring and quantifying the HMA shear properties for predicting field rutting performance.
