Newsletters

NDE of Grouted Post-Tensioned Tendons

Post-tensioned bridge tendons are normally filled by cementitious grouting after tendon stressing. In addition to bonding the strands in place, the grout provides an important role in the structure durability by protecting the post-tensioned tendon from corrosion. Unfortunately, many structures are suffering from grout voids, segregated grout and soft grout with elevated levels of sulfates that can cause corrosion...

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Anchor Bolt & Rod Inspection

Many of the signs and communication towers along our highways have been in service for many years and are of an age where it is important to test their anchor bolts and rods for flaws that could affect the ability of these structures to withstand severe weather conditions...

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Steel I-Beam Inspection

NDT uses ultrasonic measurements to determine the length and thickness of a steel I-beam's web and flanges. These measurements are critical factors for an engineer in determining the structural capacity of a beam in a building or bridge structure...

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Tomography

NDT Corporation conducted nondestructive sonic/ultrasonic measurements on 22 Piers in the switch yard of a Power Plant. The objective of this investigation was to obtain data to assist engineers in evaluating the structural integrity of the top 3 to 4 feet of the switch yard piers...

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Detection of Voids, Soft Grout and Tendon Corrosion in Internal Bridge Post Tensioning Ducts

Bridge owners recognize voids and soft grout in internal post tensioning ducts of bridges as a potential cause of tendon corrosion and a serious issue that they need to address. Nondestructive sonic/ultrasonic testing complimented with a drilling and bore scope inspection program can provide engineers with the specific locations of voids and soft grout, approximate volume of voids and an assessment of tendon corrosion, information necessary to prepare a repair plan and bid documents...

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Testing Post Tensioning Ducts for Voids

Grout voids in post tensioning ducts create the potential for corrosion and failure of tendons. Sonic/ultrasonic impact echo testing is used to locate grout voids. Voids are verified with a small drill hole and tendon corrosion conditions documented with a bore-scope video...

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Pile Length Testing

Dredging, directional drilling, tunneling, scour analysis and the reuse of an existing foundation are all projects that it is important to know how long existing piles are. NDT Corporation can determine the length of timber, concrete, sheet piles and pipe piles using pulse echo measurements (reflected compressional waves)...

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Nondestructive Evaluation of Bridges

NDT Corporation conducted sonic/ultrasonic pulse velocity measurements on box beam bridges at Houston International Airport to determine if visible cracking coincident with the spacing and location of the joints between box beams extended to and possibly through the concrete filled shear keys. Depending on the depth of a crack, wave velocity will be lower for measurement across a crack. A full depth crack through the shear key would inhibit the propagation of the waves, resulting in no discernible signal arriving at the sensor...

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