Nondestructive testing (NDT) methods for evaluating the conditions of bridge decks include ground penetrating radar (GPR) and infrared thermography (IR). GPR transmits pulses of energy into a bridge deck and measures the strength of the reflection off of the structural layers. Areas showing relatively weak reflections are associated with concrete deterioration and correlate well with corrosion potential and high chloride content. Infrared thermography is different in that it measures the surface temperature of a bridge deck. Areas with relatively high temperatures are associated with delaminations within the concrete. With infrastructure conditions worsening and funding levels remaining stagnant, high-speed evaluation methods are beginning to gain traction with an increasing number of transportation agencies.
Here are 5 key reasons why.
1. Reduced contingency funding, allowing agencies to rehab more decks with a given budget.
Duane Green, maintenance operations engineer in MnDOT’s metro district, said GPR is a useful planning tool for the department... It “helps us wisely use the repair dollars we have to use,” he said. “I don’t have to have quite as big a contingency factor. … Instead of being in the ballpark [for planning purposes], I am in the infield now.”
2. No lane closures are required, keeping the traffic moving and taxpayers happy.
Proven in past projects: http://www.prweb.com/releases/2015/04/prweb12682055.htm
3. Data-driven prioritization of preservation, repair, rehab, and replacement efforts.
“There are a number of advantages of GPR technology for bridge inspection, and the method is particularly well-suited to prioritizing for budgeting purposes.” As described by Dr. Roger Roberts (GPR expert at GSSI) in a recent article from STRUCTURE magazine titled “Inside the Bridge Inspection Toolbox”.
Read more: http://www.structuremag.org/?p=8064
4. Ability to detect damages below the surface and repair before potholes appear.
Learn more by watching this video: https://www.youtube.com/watch?v=OWkMUtjSuKE
5. Condition quantities and maps can be provided for 100s of bridge decks in just weeks
Reliable and comprehensive condition information is critical towards a successful bridge management program. The accuracy of this information translates directly to the efficiency at which rehab and replacement funds are spent. Traditional methods of chain dragging, hammer sounding and visual inspection are highly subjective, labor intensive, and provide limited detection capability. The use of emerging high-speed scanning technologies, such as GPR and infrared, provides measurable data that, with proper analysis, can be converted into actionable information. For bridge decks this information comes in the form of delamination, deterioration, spalling, and patching quantities and maps.