Figure 32: Joint survey [63

content up to 14.6%. Interestingly, data suggested that compaction at the wheel path was more consistent than other locations (nearly 1/10 of the variability observed at the lane and joint). This may have happened due to Maine DOT’s focus on wheel path compaction for QA/QC testing. Likely contractor practices evolved to produce high level wheel path compaction. However, the report suggests that future implementation of the DPS in Maine must include data from lane and joint as many studies have conclude that compaction in other parts of the pavement, especially at the longitudinal joint are essential for adequate pavement performance.

HWY 2 near Lincoln, Nebraska

This survey was a training exercise in which the DPS measurement process and calibration with cores was demonstrated and explained to the Nebraska DOT. Compaction was considered satisfactory and mostly uniform for both areas in the center of the lane and at the joint. However, some points presented scarce areas of low dielectric constant indicating potential issues with compaction (Figure 32). Using DPS in active projects can help improve compaction these locations.

Figure 32: Joint survey [63]

48

HWY 9 near Clifton, Maine

A DPS survey was conducted by Maine DOT in both the shoulder and in the mainline over all sections. To maximize the area of the surveys, the DPS was adjusted with a wider default sensor offset of 2.75 ft. Results indicated, similar to the other surveys described above, an overall uniform compaction. Shoulder and mainline presented similar dielectric values. However, adjusted left sensor consistently reported a lower compaction. The report does not mention a reason for this. Also, as seen in other sections a few locations of low dielectric were observed.

I-95 Near Pittsfield, Maine

For this section, the study reports overall consistent compaction as estimated by the dielectric constant. Figure 33 presents the dielectric maps for segments 1 through 4 measured near the longitudinal joint. As known, joint compaction is often lower than the center of the lane. Results from this section demonstrated (Figure 33) the lower joint compaction as measurements 1.5 ft away from the joint suggested high air void content (consistent lower dielectric values) at the joint.

49