Technical Papers

Nondestructive Testing of a Trunk Sewer Line

Constructed in the early 1900's with an unreinforced concrete top section and a vitrified brick base (below spring line), the B Street-New Jersey Trunk sewer is located in the center of Washington D.C. This sewer tunnel varies in size, shape and construction; transitioning from a 6' 6" circular brick tunnel upstream to a 17' X 16' concrete sewer with a brick bench downstream...

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Nondestructive Testing For Accelerated Bridge Construction (ABC) Projects

The replacement of bridge superstructures and decks as part of accelerated bridge construction (ABC) relies on the existing foundations to support the new structure. This requires engineers to assess the existing condition of the foundations, confirm as-built details and if as-built plans do not exist, determine how the foundations are constructed. Nondestructive testing is an accurate and effective means used by engineers to obtain this information...

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Measuring the Condition of Prestressed Concrete Cylinder Pipe

Prestressed Concrete Cylinder Pipe (PCCP) is a complex composite structure. For the pipe to function properly, all elements of the structure have to perform as intended. Sonic/ultrasonic testing can be used to evaluate these elements in PCCP. Failures of any elements of the composite structure such as a reduction in the concrete core strength, a delamination between layers of the composite structure, micro-cracking or cracking of the core, indicate the pipe section is not functioning as intended therefore compromising structural integrity....

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Nondestructive Testing For Voided and Soft Grout in Internal Post-Tensioning Ducts

Post-tensioned (PT) bridge construction has been used for decades. This construction is popular because it is economical to construct long-span structures over water or difficult terrain or in congested urban areas where traffic disruption can be an issue. PT bridges often have precast or cast-in-place segmental box sections or girders with internal ducts so that tendons can be inserted between bridge segments and stressed so that the sections are in compression under dead and live load. After the tendons have been stressed, the annular space....

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