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Pavement Density Profiler (PDP)

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here has been extensive research that shows that the life expectancy of asphalt pavement is highly dependent on uniform asphalt compaction. The widely accepted quality control metric for new paving is to drill core samples in the finished road and then, measure their density in the laboratory. The coring process, besides being destructive, typically takes days, and the results from the lab are received long after the pavement has cooled and there is any chance of taking corrective action if problems are found.

Other methods of measuring pavement density include electrical capacitance (PQI) and nuclear density gauges. The use of nuclear density gauges is complicated due to the safety, security and transportation regulations required for the handling of radioactive source materials.

asphalt road pavement layer density profiler

 

asphalt pavement crack, joint, rutting distress

 

“Proper compaction of an asphalt pavement is essential for long-term pavement performance. Studies indicate a 1 percent increase in density can extend the asphalt pavement service life by at least 10 percent.”

Federal Highway Administration, U.S.
Department of Transportation

Many jurisdictions do not accept or use nuclear gauges. Like coring, these methods only sample a small area of the pavement, typically 100 cm2. The challenge is knowing if enough samples have been taken to ensure adequate sampling of the large road surface area. Point sampling leaves gaps in the measurements and increases the risk that there may be areas in the road that fall outside the compaction quality requirements which could lead to premature road failure.

The new Pavement Density Profiler (PDP) addresses the need to acquire density measurements over a large area of pavement quickly. Data is collected in a non-destructive and non-contacting manner and displayed in real-time during the paving process to quickly assess the uniformity of the paving job.

The PDP measures the variability of the asphalt pavement and can collect data in point (Figure 1), profile (Figure 2) and area mapping (Figure 3) modes of operation, providing more complete density measurements than destructive coring. Areas of high and low density can then be targeted for further investigation.

The PDP works by transmitting a radio wave signal towards the ground surface and detecting the reflected wave, measuring the dielectric permittivity of the asphalt pavement. This information can be converted to density or air void content values for real-time, in-field results.

pavement Density Gauge
Figure 1
PDP point measurement PDF report. The PDP samples a point on the asphalt pavement thousands of times in 30 to 60 seconds and generates statistics and a histogram of the results.

 

The complete PDP system is housed in a single battery-powered unit that connects wirelessly to a tablet for viewing and control of the system. This simplifies training, field setup and operation and ensures consistent field results.

There are many powerful and innovative features in the PDP, including:

  • Setup & Survey in minutes
  • Factory calibration – no need for complicated or tedious in-field calibration
  • Quick, in-field validation process to ensure system performance before work begins
  • Automated reports in PDF format
  • Data export in CSV (spreadsheet) format
gpr asphalt concrete Density Gauge
Figure 2
PDP profile data collected every 0.1 meters across two lanes. The profile plot (b) shows that the density of the seam is low compared to that of the 2 lanes.

 

asphalt Non-nuclear Density Gauge
Figure 3
PDP 2D Area plot (plan map view). Ten PDP profiles were collected 1 meter apart across two lanes. The density map image shows the variation in density, including high and low densities around the seam between lanes.

 

The PDP lowers costs by reducing the need for expensive cores and optimizing the coring locations to anomalous areas. Further, pavement compaction procedures can be adjusted on an ongoing basis by eliminating the delay between paving, coring and lab measurements. The PDP brings a new level of functionality and efficiency to measure pavement properties.

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