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South Dakota Department of Transportation
Project Synopsis
SD1994-12


Title: Impact-Echo Testing
Project Researcher: Dan Johnston, SDDOT
Project Manager: Daris Ormesher
Research Period: -
Status:
Cost: $0.00

Problem Statement:SDDOT has purchased hardware and software for impact-echo testing. This equipment uses transient stress waves for nondestructive testing of concrete structures. National research has shown the impact-echo method effective for determining defects in concrete structures, beams, and columns. The defects identified include detecting cracks, honeycombing, delaminations, pavement thickness, and voids in plain and reinforced concrete with and without asphalt concrete overlays.

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.

Findings:
Title: Impact-Echo Testing
Project Researcher: Dan Johnston, DOT
Project Manager: Daris Ormesher
Research Period: -
Status:
Cost: $0.00

Problem Statement:SDDOT has purchased hardware and software for impact-echo testing. This equipment uses transient stress waves for nondestructive testing of concrete structures. National research has shown the impact-echo method effective for determining defects in concrete structures, beams, and columns. The defects identified include detecting cracks, honeycombing, delaminations, pavement thickness, and voids in plain and reinforced concrete with and without asphalt concrete overlays.

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.

Findings:

Research Objectives:
1  Determine uses of the impact-echo test method relative to SDDOT activities.
2  Develop test methods and procedures for detection of delaminations in bridge decks and PCC pavement thickness determination.
3  Develop recommendations on implementation of test methods, policies and procedures to allow the use of the impact-echo test method.

Research Tasks:
1  Review literature on impact-echo testing, particularly policies and procedures developed by other states and agencies.
2  Perform impact-echo testing on bridge decks for detection of delaminations and pavements to determine thickness.
3  Evaluate the results obtained in task 2 and determine accuracy and reliability factors.
4  Investigate the feasibility of using the impact-echo test method to evaluate a variety of defects that may occur in SDDOT pavements and structures. Defects the equipment may be used to detect and quantify include but is not limited to the following:
5  Develop policies and procedures regarding the use of impact-echo testing based on testing performed in task 2 and task 3.
6  Prepare and submit a final report summarizing the problem, literature review, research methodology, findings, conclusions and recommendations.
7  Make an executive summary presentation to the Department of Transportation's Research Review Board.

Documents Available:

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