Nondestructive Testing of Infrastructure

During concrete deck inspection, ground penetrating radar (GPR) can produce images of embedded reinforcements such as rebar. Thermal/infrared testing (IR) can assess subsurface discontinuities and deterioration.

For inspection of pins, hangers, and eye bars, UT is particularly effective for detecting subsurface cracks while magnetic particle testing (MT) and liquid penetrant testing (PT) can identify fatigue cracks in critical steel components.

During assessment of steel girders and trusses, electromagnetic testing (ET) is useful for surface cracks, while radiographic testing (RT) and acoustic emission testing (AE) can detect internal flaws.

NDT technicians evaluating concrete columns and foundations look to UT to assess the integrity of the concrete, while GPR can help them locate embedded reinforcements. Sonar (a type of UT) is particularly useful for underwater inspections.

Inspection looks for voids, delamination, and rebar corrosion in concrete structures. GPR can locate embedded reinforcement and voids; UT measures sound pulse velocity to assess the integrity of concrete; and AE techniques such as impact-echo testing identify delamination and other subsurface defects.

NDT technicians regularly inspect steel frames of buildings to detect cracks, weld defects, and other discontinuities. MT is effective for surface and near-surface crack detection; UT can detect subsurface flaws; and RT provides images of the internal structure of welds and other components.

Facade inspection of buildings typically starts with VT, with the NDT technician carefully looking for signs of moisture intrusion, delamination, and other defects. IR can identify temperature anomalies associated with moisture and delamination, and AE can detect the sound of cracking or other structural changes.

VT is also the first step in roof inspection, allowing an NDT technician to detect moisture intrusion, insulation defects, and structural integrity issues. Technicians can then use IR to identify areas of moisture intrusion and insulation defects and UT to assess the integrity of roofing materials.

Foundation inspection of buildings requires methods that can assess the condition of the foundation underground. GPR can locate voids and assess the overall condition of the foundation; UT can detect subsurface cracks; and ET can identify changes in the material properties of the foundation.

Pavement condition assessment is a continuous NDT activity for roads. Inspections rely on methods such as GPR to locate subsurface defects and assess layer thickness and IR to identify temperature anomalies associated with defects.

Inspection of tunnels and bridge decks are included in road infrastructure maintenance, and NDT technicians rely on methods such as GPR for locating and mapping rebar and voids, UT for assessing the integrity of concrete and steel components, and VT for identifying surface defects.

Roadway subsurface investigation methods such as GPR and ET help detect changes in material properties to proactively ensure road subgrade integrity.

Asphalt compaction quality control depends on GPR to assess and ensure uniformity and consistent density of asphalt layers during road building and repaving operations.