Infrasense Uses GPR to Measure Pavement Density in Washington State

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Infrasense has recently participated in a pavement density investigation of new asphalt in Washington using its proprietary software for measuring and mapping pavement density using ground penetrating radar. GPR provides complete coverage of a new asphalt pavement, and can be used to map areas of relatively higher and lower density within the pavement.

Infrasense's GPR system for new pavement density investigations

Infrasense, Inc. has recently completed an asphalt pavement density investigation for the Washington State Department of Transportation (WSDOT). The purpose of this pavement investigation was to provide asphalt density measurements and mapping across two driving lanes of a 3000-foot section of newly paved road. The investigation was performed using Infrasense's vehicle-mounted GPR system so that density data could be collected quickly and efficiently, without interfering with normal construction procedures. The results of the GPR testing were used to locate density variations within the newly constructed pavement, and to assess the overall consistency and performance of the Intelligent Compaction paving system.

Achieving the target density for a pavement is particularly important for long-term pavement performance. Pavement density is a measure of Quality Control and Quality Assurance (QC/QA) of new pavement construction projects. Traditionally, density has been measured using cores or nuclear density gauges. However, these methods provide data at only a limited number of random locations, and working with nuclear gauges can require special licensing. The GPR-based system developed by Infrasense provides 100% coverage of the entire pavement on-site, revealing potential patterns of low density, such as along joints and at stopping points. The system has previously been implemented by the Florida DOT and Minnesota DOT. Additionally, over the past year, CalTrans and NHDOT have used GPR to supplement the Intelligent Compaction evaluation program.

Infrasense’s GPR system for pavement density measurement consists of a single or dual air-coupled radar antenna (s) mounted to the front or back of a survey vehicle. The GPR data is collected in a series of lines spaced 2 feet transversely across the width of the pavement, with each line representing a cross sectional slice of the pavement at a particular offset. Infrasense integrated a photo-reflective laser switch into the system to automatically insert marks in the GPR data for the start and end of the section being surveyed. Infrasense modified the antenna settings to enhance the near-surface resolution of the data and to collect data more frequently than traditional GPR surveys.

In order to assess the pavement on-site, Infrasense developed processing software (GPRQA) that automatically analyzes the GPR field data to produce color contour maps of the asphalt surface dielectric, which is proportional to the density. The analysis can be carried out on site or in the office. By analyzing these maps on-site for stronger and weaker dielectrics, cores can be taken at optimum locations for calibration.

About Infrasense, Inc.

Since 1987, Infrasense, Inc. has applied state-of-the-art technologies to address the most difficult challenges in subsurface scanning. Infrasense’s engineers are able to nondestructively extract critical information from a diverse range of structures. In addition to providing ongoing subsurface evaluation services to clients across the country, the firm has also conducted numerous research programs to advance the field of subsurface detection and non-destructive evaluation. To learn more about Infrasense and the services we provide, visit our website:

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Sarah Kelly
Infrasense, Inc.
+1 (781) 648-0440
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