USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation


FAST NDE Laboratory | Specimen Library

FAST NDE Laboratory

The Federal Highway Administration’s (FHWA’s) Advanced Sensing Technology (FAST) NDE Laboratory is a unique facility for the development and testing of NDE technologies. The FAST NDE laboratory works with different offices and programs within FHWA and with other stakeholders to address their growing needs with state-of-the-art NDE tools. Some of the technologies researched at the laboratory include: conventional/phased array ultrasonics; conventional/advanced eddy current; acoustic emission; ground penetrating radar; infrared thermography; impact echo; Structural Health Monitoring (SHM) systems; autonomous tools for condition assessment and automated data collection, analysis, interpretation, visualization and data fusion; and both noncontact and remote sensors.

The laboratory is outfitted with new equipment and tools, such as a KUKA robotic arm (KR 10 R1100 sixx) with a payload of 10 Kg to handle test specimens, multiple NDE equipment, such as a phased array ultrasonic testing system for steel component inspection and ground penetrating radar for concrete inspection (see Equipment page for a complete list).

"The three-dimensional, computer-generated drawing is a view of the proposed laboratory interior. On the left wall of the image and left half of the back wall are wall-mounted work tables and shelves. On the right wall and right half of the back wall are desks and chairs. Two handcarts are positioned in the middle of the image, along with an armed marked “Cart Storage”. Two additional unidentifiable pieces of equipment are in the mock-up."
Figure 1. Image. Artist’s rendition of the FAST NDE Laboratory.

"Interior photo of the NDE laboratory."
Figure 2. Photograph. The FAST NDE Laboratory.

Specimen Library

The FAST NDE Laboratory has an extensive collection of component specimens to support the NDE program. Component specimens include small sections of highway structures (both in pristine conditions and with known defects) that have been removed from in-service bridges or that are manufactured to represent realistic structural components. The collection of component specimens is continually evolving as specimens become available from decommissioned bridges, are purchased from qualified vendors, or are manufactured in the NDE Laboratory. A summary of the specimens currently at the NDE Center is described below.

Concrete Specimens

The lab houses a pair of full-sized (54-inch-tall by 85-foot-long AASHTO girders) prestressed bridge girders that were removed from an active bridge on Maryland I–90. These girders were installed in 1971 and were in service until they were salvaged to be used for full-scale research in a laboratory setting at the Turner-Fairbank Highway Research Center (TFHRC). The girders were placed on four reinforced soil abutments, suspended approximately 10 feet above the ground (figure 3).

"Two bridge girders are shown from an angle. The girders are parallel to each other and each girder is positioned on two cinder block pillars. Each girder assembly is approximately ten feet in height. The girders are positioned diagonally in the photo, with the right end in the foreground, and the left end of the girder in the background. A ladder rests on its side in the right portion of the photo, and an 18-wheeler truck can be seen in the right background."
Figure 3. Photograph. Full-size prestressed bridge girders.

Three validation slabs, measuring 4 feet long, 6 feet wide, and 8 inches high, are also available to verify the applicable and promising methods used on girders (figure 4). The validation slabs were constructed with prestressing strands laid lengthwise throughout with known amounts of strand damage artificially created at known locations. Each validation slab has 26 untensioned half-inch 7-wire stands arranged in 3 vertical layers and 15 longitudinal rows. Several different scenarios of damage were created in each slab, including 5 percent, 10 percent, 25 percent, and 100 percent section loss at predetermined locations (figure 5).

"The photograph was taken from an oblique overhead angle. Centered in the photograph is a 4-ft long by 6-ft wide recently poured concrete slab. The slab is contained within a rectangular wooden form or mold. Portions of two similar concrete-filled wooden molds can be seen in the right rear portion of the photograph."
Figure 4. Photograph. Validation slabs after pouring.

"Three wire strains are positioned horizontally across the photograph. Each strain consists of several smaller strands wound together. The middle wire strand has is marked with two pieces of red tape, and the wire segment between the tape has been shaved halfway through, showing the internal construction of the strand."
Figure 5. Photograph. Artificially created strand damage.

The specimen library also includes a 6-foot long, 8-foot wide, 9-inch high concrete slab with built-in delaminations at predetermined locations used as a blind testbed for NDE technologies (figure 6). Multiple methods are used to create these delaminations, such as embedded cardboard, sandwich concrete plates, and polyethylene sheets, with the purpose of studying applicability and viability of NDE technologies and tools to detect these built-in defects.

"A rectangular slab is viewed from an overhead angle. The surface of the slab has been scored with lines forming a grid. The concrete slab is secured to a wooden pallet with wire bands and cardboard has been inserted between the wire bands and the concrete to prevent damage to the slab."
Figure 6. Photograph. Concrete slab with built-in delaminations.

Seven slabs are available to identify effective and promising NDE techniques to assess the performance of concrete bridge deck overlays and detect and characterize deterioration in deck overlays (figure 4). The slabs, with seven types of overlays, measure 10 feet long, 40 inches wide, and 8 inches thick. The slabs were built with various artificial defects including delamination, honeycombing, void, vertical crack, and precorroded rebar within an elevated chloride content environment. Half of each overlay was bonded to the underlying concrete slabs; the other half was debonded.

"Epoxy, latex (covered by a white sheet), silica fume (covered by a blue sheet), and polyester polymer overlays after construction."
Figure 7. Photograph. Epoxy, latex (covered by a white sheet), silica fume (covered by a blue sheet), and polyester polymer overlays after construction.

"Construction of asphalt overlays with liquid membrane, sheet membrane, and without a membrane."
Figure 8. Photograph. Construction of asphalt overlays with liquid membrane, sheet membrane, and without a membrane.

"Construction of asphalt overlay specimens utilizing a nuclear density gauge to ensure adequate compaction."
Figure 9. Photograph. Construction of asphalt overlay specimens utilizing a nuclear density gauge to ensure adequate compaction.

To test the anchorage systems of highway barriers in the laboratory setup, a 12-foot long, 8-foot wide, 8-inch high mockup bridge deck along with concrete barriers are available in the laboratory (figures 10 through 13). The barriers selected were attached to the mockup bridge deck using four #4 and four #6 reinforcing steel bars with different levels of simulated cross-section loss (0, 10 percent, 25 percent, and 50 percent), as shown in figure 14 .

"A rectangular piece of concrete lying flat on a grassy/dirt area is displayed. One third of the concrete piece has a vertical scoring line."
Figure 10. Photograph. Mock bridge deck. 

"Two 3-ft high concrete barriers are viewed from a side angle. The barriers are parallel and upright with approximately 1 ft of space between their sides. The bottom surfaces of the barriers are in contact with the ground. The barrier in the foreground has suffered damage in its upper left corner and in two locations on its bottom edge. In addition, the left portion of the barrier exhibits severe abrasion."
Figure 11. Photograph. Retired service barrier.

"Six concrete barriers of various shapes and sizes are lined up in an upright position on a dirt/gravel patch. The barriers The two front barriers are of similar size and shape, approximately 3-ft tall and 12-ft long. Halfway along the bottom edge of the front barrier, significant chipping damage is displayed. A faint grid pattern can be seen along the length of the barrier."
Figure 12. Photograph. Jersey barrier with delaminations.

"Six concrete barriers are viewed from a side angle. The barriers are in and upright, standing position, and are roughly parallel. The three barriers shown from the far right to middle screen are designed with four vertical channels. End fasteners can be seen on two of the three barriers. At the bottom of each channel is a vertical hole that is used to bolt the barrier into place."
Figure 13. Photograph. Barriers with delaminations.

"Two concrete barriers are positioned parallel to each other on a concrete slab. The photograph is taken from the end of the barriers viewing down the pathway between the barriers. In the background is a white panel truck. The left barrier is a solid form and is labelled “New Jersey Type”, while the right barrier has four vertical channels to enable bolting down and is labelled “F-Shape Bolt Down’. Metal rods are inserted in the holes within the vertical channels. In addition, each bolt down hole has been labelled starting from the far end of the barrier with 0%, the next one is labelled 10%, the following hole is labelled 25%, and the final hole that is closest to the view is labelled 50%. A piece of wood is supporting the front right corner of the concrete slab."
Figure 14. Photograph. Simulated cross-section loss of rebar at F-shape bolt-down barrier connection and New Jersey barrier connection.

Three bridge decks, measuring 30 feet long, 5 feet wide, and 8 inches thick, were salvaged from the replacement of the Haymarket highway bridge in 2015 for full-scale, long-term NDE research in a laboratory setting at TFHRC (figure 15). The Haymarket bridge was built in 1979 with reinforced concrete decks on continuous steel girders. The three salvaged decks were placed on two reinforced soil abutments, suspended approximately 7 feet above the ground at TFHRC. The condition of the decks has been repeatedly evaluated using various NDE techniques including infrared camera, electrical resistivity, impact echo, ultrasonic surface waves, ground penetrating radar, and ultrasonic tomography.

"Three bridge decks from the Haymarket highway bridge."
Figure 15. Photograph. Three bridge decks from the Haymarket highway bridge.

Steel Specimens

This collection includes samples from steel bridges with different configurations. The specimens have different joint geometries, material thicknesses, coatings, and weld defects. The inventory includes a number of butt-weld specimens with Complete Joint Penetration (CJP) groove welds, butt-welds with well-bonded bridge coatings, and T-joint specimens with fillet weld butt joints. Engineered cracks are embedded in these specimens and a variety of crack geometries are represented.

Bare Metal Steel Specimens

Figures 16 through 20 show each of the specimen’s geometries. The specimen base metal complies with ASTM A709 material specifications. All fabrication and welding was performed in accordance with the American Welding Society (AWS) D1.5 Bridge Welding Code.

"The photograph consists of a large metal surface showing two smaller rectangular metal plates that have been welded in place. The longer metal plate is horizontally positioned in the photograph, with the shorter metal plate placed perpendicularly. The welds joining the edges of the smaller plate to the rectangular surface are clearly visible."
Figure 16. Photograph. Typical T-Joint specimen with fillet welds.

" The photograph consists of a large metal surface showing two smaller rectangular metal plates that have been welded in place. The shorter metal plate is horizontally positioned in the photograph, with the longer metal plate placed perpendicularly. There is a significant gap between the two perpendicular pieces. The welds joining the edges of the larger plate to the rectangular surface are clearly visible."
Figure 17. Photograph. Typical T-Joint specimen with fillet welds. 

"The photograph is an overhead view of two rectangular plates joined with a butt-weld to create a larger rectangular plate. Some corrosion is present in the welded plates. The specimen is labeled NDE-10."
Figure 18. Photograph. Typical butt joint specimen with CJP groove welds.

"The photograph is an angled overhead view of two polished rectangular plates joined with a T-weld. The larger plate is resting flat on a surface and the smaller plate is perpendicular. The specimen is labeled NDE-13."
Figure 19. Photograph. Typical T-Joint specimen with fillet welds.

"Typical heavy thickness specimens with butt welds"
Figure 20. Typical heavy thickness specimens with butt welds.

Coated Steel Specimens

The purpose of the coated specimen shown in figure 18 was to evaluate the effect of typical bridge coatings on measurements. The specimen was coated with a typical three-coat bridge system. The three-coat bridge system comprises of an organic zinc-rich primer, an epoxy intermediate, and polyurethane topcoat applied by KTA-Tator. This coating was a mixture of KTA-Tator’s Carbozinc® 859; Carboguard® 893SG with optional (LT) cure, and Carbothane 133 LH products. This coating system is a well-established and commonly used system by departments of transportation in the United States.

"A two-dimensional view of a painted rectangular metal plate. A circle is marked within a small etched rectangle in the approximate center of the plate. The specimen is labeled NDE-8."
Figure 21. Photograph. Typical coated specimen.