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Characterization of Deterioration Progression in Concrete Bridge Decks from Periodical Multi NDE Technology Surveys

Nenad GUCUNSKI 1, Brian PAILES 2, Jinyoung KIM 3, Hoda AZARI 4 and Kien DINH 5

1 Rutgers, The State University of New Jersey, 96 Frelinghuysen Rd, Piscataway, NJ 08854, USA, +1(848) 445-2232; email: [email protected], [email protected], , [email protected], [email protected],

[email protected] 2 Vector Corrosion Services, Inc., 1936 Bruce Downs Blvd. #315, Wesley Chapel, FL 33544, USA,

[email protected] 3 Rutgers, The State University of New Jersey, 100 Brett Rd, Piscataway, NJ 08854, USA, [email protected]

4 Federal Highway Administration, Turner-Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101, USA, [email protected]

5 Rutgers, The State University of New Jersey, 100 Brett Rd, Piscataway, NJ 08854, USA, [email protected] Abstract Long term condition monitoring of a bridge deck is accomplished through periodical surveys using five complementary nondestructive evaluation (NDE) techniques. The monitoring concentrated on three main components: evaluation of corrosive environment and corrosion processes, concrete degradation evaluation, and assessment with respect to deck delamination. Five NDE techniques were used: impact echo (IE), ground penetrating radar (GPR), half-cell potential (HCP), ultrasonic surface waves (USW) method, and electrical resistivity (ER). The ability of the NDE methods to objectively capture and characterize deterioration progression is illustrated by the results from four NDE surveys of a bridge in Virginia during a five and a half year period. The deterioration progression is illustrated by condition maps, condition indices, and from those deterioration curves. Keywords: Concrete, bridge decks, deterioration, corrosion, delamination, nondestructive evaluation (NDE), ground penetrating radar (GPR), impact echo, half -cell potential, electrical resistivity, surface waves

1. Introduction Reinforced concrete bridge decks are deteriorating faster than other bridge components, in the greatest part due to their direct exposure to traffic and environmental loading, and the associated maintenance activities. Good management also requires implementation of realistic deterioration, predictive and life cycle cost models. Condition monitoring of bridge decks through their periodical inspections using nondestructive evaluation (NDE) techniques has high potential to provide the critically needed more comprehensive, quantitative and objective condition information. The paper provides results of a five and a half years long condition monitoring of a concrete deck of a bridge in Virginia through four periodical NDE surveys. The ability of the NDE methods to detect and quantify deterioration progression is demonstrated through a comparison of generated condition maps, and calculated condition indices. It is also demonstrated that condition indices can be the basis for quantification of deterioration progression and thus development of more realistic deterioration and predictive models. 2. Haymarket Bridge study 2.1 Description of bridge and NDE surveys The bridge surveyed is located on State Route 15 over Interstate 66 in Haymarket, Virginia. It is a two-span continuous steel girder structure with a bare concrete deck (Figure 1), constructed in 1979. The bridge deck is 84.1 m (276 ft) long, 13.8 m (42 ft) wide and 21.5 cm (8.5 in) thick.

International Symposium Non-Destructive Testing in Civil Engineering (NDT-CE)

September 15 - 17, 2015, Berlin, Germany

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The bridge has a skew angle of 17 degrees. The deck was evaluated as a part of the Federal Highway Administration's (FHWA's) Long Term Bridge Performance (LTBP) Program in September 2009, August 2011, October 2014 and June 2015. The average daily traffic (ADT) and average daily truck traffic (ADTT) during the past five years was around 13,000 and 600, respectively. The bridge deck received National Bridge Inventory (NBI) rating 6 during the 1992 to 2014 period. However, and it will be illustrated later by the NDE results, there was significant deterioration progression even during the 2009 to 2015 period.

As illustrated in Figure 1, the surveys were conducted on a 0.6 m by 0.6 m (2 ft by 2 ft) grid. The first line of the grid was offset 0.3 m (1 ft) from the parapet. All the "point-based measurement" technologies are using the same grid, while the GPR is scanning the deck in the longitudinal direction of the deck, perpendicular to the orientation of the top rebars, with a 0.6 m (2 ft) spacing between the survey lines. The two principal methods for the assessment of corrosion within the LTBP Program include electrical resistivity (ER) and half-cell potential (HCP) measurements. While the first one concentrates on the assessment of corrosive environment, and from those estimation of corrosion rates [1], the second one evaluates probability of active corrosion [2]. Impact echo (IE) is the primary NDE technique within the LTBP Program for detection and characterization of deck delamination. It enables detection of delamination, its position and the stage of its progression [3]. The GPR provides a qualitative assessment of the concrete condition, including potential concrete deterioration, delamination and corrosive environment [4]. Finally, the Ultrasonic surface wave (USW) method enables quantitative assessment of concrete through the measurement of concrete elastic modulus [5]. It has been demonstrated that very low modulus values are often indications of likely delamination at the test point [6].

Figure 1. NDE technologies simultaneously deployed during the data collection.

Impact Echo

ElectricalResistivity

MoistureScan

USWGPR

Half-CellPotential



2.2 Periodical NDE survey results The results of the four NDE surveys are summarized and presented in terms of condition maps and condition indices, and deterioration curves developed based on the condition indices. The first two elements are illustrated for the GPR results. deterioration progression from the GPR surveys is illustrated in Figure 2. Areas with high attenuation levels describing the anticipated serious condition, both expanded and became more severe during the five and a half year period. Condition maps from other technologies show very similar trends.

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Figure 2. GPR condition maps for Haymarket Bridge deck from 2009 (top) to 2015 (bottom). To describe the overall condition, the GPR based condition index is calculated according to 罫�迎稽�嫌結穴系剣券穴�建�剣券 �券穴結� =

畦罫 × 100 + 畦繋 × 70 + 畦� × 40 + 畦鯨 × 0畦劇剣建��

where AG, AF, AP, and AS are the areas with the GPR signal attenuation (normalized dB) ranges of > -15, -15 to -17, -17 to -20, and < -20, respectively. Finally, the deterioration progression is described in terms of condition indices in Figure 3. Each of the curves for the five technologies, and the combined condition curve is defined by five points. Those points include the four indices from the four surveys and assumed condition index of 100 for the time of construction in 1979. Certainly, the path or shape of the curves between 1979 and 2009 is unknown and is yet to be better defined as a part of the LTBPP evaluation of bridges of different ages.



Figure 3. Deterioration curves for the Haymarket Bridge deck.

3. Conclusions Results of four surveys conducted over a period of five and a half years have shown that use of complementary NDE technologies provides the ability to capture and objectively assess deterioration progression with time. Application of NDE also opens opportunities for the development of more realistic concrete deck deterioration, predictive and life-cycle cost models. In addition, the surveys have demonstrated high repeatability of the NDE measurements. Acknowledgements The authors sincerely acknowledge the support of Federal Highway Administration provided through the LTBP Program, especially Drs. Hamid Ghasemi and Robert Zobel. References 1. K R Gowers and S G Millard, 'Measurement of Concrete Resistivity for Assessment of Corrosion Severity of Steel Using Wenner Technique'. ACI Materials J., 96(5), 536-542, 1999. 2. ASTM, 'ASTM C876-09 Standard: Standard Test Method for Half Cell Potentials of Reinforcing Steel in Concrete', American Society for Testing and Materials, 2009. 3. M Sansalone, 'Impact-Echo: The Complete Story', ACI Materials J., 94(6), 777-786, 1997. 4. C L Barnes and J-F Trottier, ”Ground Penetrating Radar for Network Level Concrete Deck Repair Management', Journal of Transportation Engineering, ASCE, 126(3), 257-262, 2000. 5. S Nazarian, M R Baker and K Crain, 'Report SHRP-H-375: Development and Testing of a Seismic Pavement Analyzer', Transportation Research Board, Washington, D.C., 1993. 6. Yuan, D., S. Nazarian, D. Chen, and Hugo, F. (1999). "Use of Seismic Pavement Analyzer to monitor degradation of flexible pavements under Texas Mobile Load Simulator." Transportation Research Record 1615, TRB, National Research Council, Washington, D.C., 3–10.

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