Experimental Non-Destructive Testing of FRP Materials, Installation, and Performance, Dallas County Bridge, Missouri, USA

The FRP (Fiber Reinforced Polymer) retrofit of a concrete bridge in Missouri provided the opportunity to use new and existing technologies to test the FRP materials installations, and performance. Four different parameters were investigated; concrete substrate surface roughness, FRP fiber alignment, FRP delamination, and FRP bond pull-off strength. Results of testing to date are presented, and long term monitoring plans will be given. Surface substrate roughness measurements of sand blasted surfaces were made, on selected locations of the bridge abutments and bents, as well as the bridge deck, using a newly developed laser profilometer. The roughness measurements are compared to the idealized surface roughness, and compared against any future delamination, from pull-off tests and natural delamination. FRP fiber alignment measurements were made using an imaging techniques that measures the angle between control lines and special tracers embedded in the FRP materials. FRP delamination testing was done using a specially modified impact echo tester, on production surfaces and on surfaces with artificially created delaminations. All test sites are referenced with respect to previously determined substrate roughness measurements. Tests will be done every six months for the next five years. FRP bond Pull-off strength testing was done using a specially designed Pull-off tester. Testing will be done to a working load, Pull-off failure is anticipated only for defective materials or installation. Pull-off plugs were installed on selected locations on the bridge and referenced to roughness measurements. Testing will be done every six months for the next five years