Evaluation of Trapezoidal Shaped Grooves

Pavements are regularly tested at the NAPTF. The construction of asphalt test pavements within the NAPTF coincided with the beginning of the trapezoidal-shaped groove evaluation project. A cooperative, coordinated effort between researchers and NAPTF facility personnel enabled two separate, but simultaneous, studies of the same pavement to be conducted. The layout of the NAPTF test sections provided transition zones between test pavements where grooves could be installed without affecting the nature of the data collection in their other tests. Two transition zones were chosen for grooving, namely “T5” and “T6,” shown in figure 8. Each transition zone measured about 25 ft wide and provided sufficient pavement for 20 ft of transverse grooves to be cut within. The NAPTF testing of adjacent test articles “MRC,” “MRG,” and “MRS” dictated the wander path, frequency, and loading of the test machine. Therefore, the grooves would be subjected to the repetitive machine traffic and loading that was prescribed for the main test articles. No loading or trafficking was conducted specifically for the grooved sections. Based on the wander pattern planned for the test machine, it was decided that within each 20-ft-wide transition, one 10-ft lane would be grooved with trapezoidal-shaped grooves and the other adjacent 10 ft lane would be grooved with standard grooves.

Figure 8. Overview of Pavement Test Articles in NAPTF Therefore, each 20-ft-wide transition included 10 ft of standard grooves and 10 ft of trapezoidal- shaped grooves. Figure 9 is a photograph of the center portion of T5, which shows the two groove types side by side. In the photograph, the grooves on the right are the trapezoidal-shaped grooves, and the grooves on the left are the standard grooves.

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