Geophysics HM Ltd offers Ground Penetrating Radar imaging and Thermal Imagery techniques for bridge integrity assessment that are high efficiency and affordable NDT alternative options to chain dragging and visual inspections on the structure decks since they are reliable, precise, high speed and traffic independent.
Bridge structure aging and concrete deck degradation lead to inevitable rehabilitation and large maintenance activities causing complex traffic obstructions and severe economic loses to the government, tax payers and private parties that own the assets. In Canada and USA the bridges are inspected at least once every two years using conventional techniques such as visual inspections and chain dragging which are at large expensive, risky and time-consuming since they need personnel on-foot access to the traffic lanes and road closures in most of the cases.
Geophysical Survey for Bridge Deck Deterioration Assessment
The damage in the bridge concrete structure is largely related to delamination and spalling caused by corrosion of the reinforcement. Car mounted “State of the Art” geophysical NDT methods are efficiently used to image the internal structure of the concrete structure and building components, including deficiencies, delamination and spalling in bridge deck, supporting structures, retaining walls, beams, piers, columns and approaches. High resolution GPR scanning can be effectively deployed over the surface of the concrete bridge components to provide information on the internal conditions of the concrete structure and components layout not provided from visual observations. The integration of the GPR, thermal imagery and other nondestructive techniques are necessary to complete a sound and full bridge condition assessment and rehabilitation.
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Structure Internal Image
High resolution image of the location, depth and orientation of steel reinforcement and other imbedded structural elements is accurately obtained with the use of high frequency GPR. Geophysical techniques are useful for mapping and estimating the number of reinforcement bars in the structure.
Reinforcement Distribution and Rebar Cover Depth
Imaging the position and relationship between the internal elements of thee concrete structure are very important aspects to consider during the design of the concrete structure. The inadequate selection and wrong placement of reinforcement will significantly affect the strength, stability and durability of the concrete structure.
Cracking, Spalling and Delamination Imaging
Ground Penetrating Radar and Thermal Imagery are used for detecting and estimating the position, size, geometry and extent of structural cracking, spalling and delamination.
Deck Deterioration Analysis
Ground Penetrating Radar carried over concrete structures with embedded corroded steel bars will show very distinctive diffraction responses and high signal attenuation due to cracking, delamination and change of the concrete properties due to the presence of chemical sub-products of the corrosion process. The attenuation of the GPR signal generated from the steel bar is used for estimating the degree of deterioration of the concrete structure and bridge decks.