TRAINING
How to Use DPS for QC in Paving BY BRYCE WUORI
I
magine using a quality control (QC) tool that displays real-time volumetric data anywhere on your asphalt mat within seconds. With such a tool, users scan the entire asphalt mat making pro-active changes with paver setup and rolling patterns to increase density and uniformity of newly placed asphalt in the field. One technology that makes this possible is the Density Profiling System (DPS). The DPS is a non-destructive asphalt assessment tool that implements ground penetrating radar technology to collect surface dielectric of compacted asphalt roadways. Within the asphalt industry, the DPS has, so far, been used as a quality assessment tool for owners. The main objectives of using this tool within a quality assessment process would be to increase safety in the field, decrease the amount of destructive coring performed on new asphalt roads, and generate more data sets that better represent the newly placed asphalt. Using the DPS technology as a quality assurance (QA) tool has a great deal of potential within the industry with many states performing pilot projects and developing new specifications that integrate the technology into current methods. Because DPS can offer such confidence to departments of transportation as a QA tool, it is gaining ground for QC in the field, too. The DPS is Wuori Consulting LLC’s “go to” QC tool when issues develop in the field with density or uniformity. Within this article, users will learn the practice of implementing the DPS as a QC tool for improved project success.
DPS SETUP FOR QC
Within the technology industry, there are numerous equipment companies that have developed a DPS that will satisfy the requirements for implementing the tool for QC. The specific DPS unit that we use at Wuori Consulting LLC is the PaveScan RDM 2.0 developed by GSSI. We feel that it is user friendly, durable and able to produce accurate data sets with maps for real-time evaluation. 16 | JUNE 2022
Getting the PaveScan RDM 2.0 DPS ready for collection takes a few simple steps for assembly and calibration. 1. Connect antennas to the unit 2. Install batteries for power source 3. Mount the collection screen to the unit handle 4. Connect the chords in the correct locations This process takes approximately five minutes and once assembled the unit can fold up into a more compact position for loading or transporting. Once the DPS unit is assembled, users can power up the transmitter and collection screen and move into the project setup and calibration. Project setup within the collection screen establishes your current project and the amount of detail you want included for the project is entirely dependent on the user’s preference. Typically, for QC applications, users will set up a project and input variables that may include project name, mix type and project location. Following the project setup, users can begin the antenna calibration procedure. The air calibration and metal plate calibration will take less than two minutes to complete but must be performed correctly for accurate data collection in the field. With the DPS assembled and calibrated, users can begin data collection procedures in the field.
DPS SETUP FOR ROLLER PATTERNS
Roller pattern setup will differ from one project to the next depending on the variables presented and the project conditions that need to be satisfied. Using the DPS to identify what roller pattern generates the best results to match your project variables and conditions will develop a higher quality project. Higher profits and incentives for ride and density will follow. When implementing the DPS as a QC tool in the field for roller pattern setup, Wuori Consulting LLC will collect most of the DPS data behind the intermediate and finish roller positions. Typically, behind the intermediate roller we have achieved most of our required project density on the asphalt mat,
This image shows the DPS swerve method for quality control data collection.
and the user can still make pro-active adjustments if required. Another reason data is typically collected in these locations in the field, is because the DPS does not respond well to water on the surface of the asphalt mat. If the rollers are using too much water and leaving water lines on the surface of the asphalt, the DPS will identify these areas and produce distorted data for the user. Managing water for rollers is a best practice that should always be monitored in a roller plan and this variable becomes even more important with the introduction of a DPS as a QC tool in the field.
DPS SWERVE PATTERN
There are two methods users will most commonly implement when verifying and modifying roller patterns in the field. These methods consist of the DPS swerve pattern and the transverse slice pattern. The swerve pattern will be the most common method used to collect data behind rollers and identify uniformity and density conditions. This collection method is performed just as it sounds. Users will identify a starting point behind the intermediate roller
