Accurately determining the amount of delaminations in a bridge deck is important to determine the structural condition of a bridge deck. The impact-echo equipment may be used to accurately determine the amount of delaminations in the deck. Currently SDDOT uses chain drag, deck cores and visual examination to determine delaminations in a bridge deck. These are the primary methods used for determining delaminations in a bridge deck. The chain drag is subject to how the operator interprets what he hears and is affected by moisture, debonding of surface overlays and local noises drowning out the sound of the chain drag. Visual inspection can be hindered if the deck has been surface overlaid or if the delaminations are not on the surface of the deck. Coring is labor intensive and can not be used effectively to plot delamination areas. Impact-echo testing could have an important impact on plan development particularly in determining the proper rehabilitation technique for a bridge deck.
Impact-echo testing is quicker and less labor intensive than coring to determine the thickness of PCC pavement. Impact-echo testing could be performed before the pavement reaches full strength, making use of the construction traffic control in most cases. The coring truck cannot be allowed on the concrete until it reaches full strength. This may require multiple trips to the project to obtain the cores necessary for thickness determination.
It is necessary for SDDOT to develop policies and procedures governing the use of this equipment for structural evaluation of bridge decks and pavement thickness determination. There may be other areas where the impact-echo test method could be of use. However, structural evaluation of bridge decks and pavement thickness determination are the highest priority.