W. Spencer Guthrie, Ph.D., M.ASCE, Department of Civil and Environmental Engineering

Brian A Mazzeo, Ph.D., Department of Electrical and Computer Engineering

Evaluation of how well the academic objectives of the proposal were met

The objectives of this research were to obtain samples of four decommissioned concrete bridge decks that were replaced as part of the Interstate 15 (I-15) CORE project in Utah County and evaluate their condition using both non-destructive and destructive testing techniques. Because the decks were not returned to trafficking, extensive destructive testing could be performed. The testing was important for providing information about long-term deterioration mechanisms that occur in Utah bridge decks. Furthermore, because each of the sampled decks had been surfaced with an asphalt membrane-overlay system, testing the decks provided useful information about the efficacy of this rehabilitation approach commonly used on bridge decks nationwide.

The following four decks were sampled:

1. I-15 northbound lanes over the Union Pacific Railroad tracks at 820 N in Provo (1964 construction with uncoated reinforcing steel)
2. I-15 northbound lanes over the Utah Transit Authority tracks just south of Deck 1 (1964 construction with uncoated reinforcing steel)
3. I-15 southbound median lanes over Center Street (1984 construction with epoxycoated reinforcing steel)
4. Provo Center Street over the UPRR tracks at 1200 W in Provo (1937 construction with uncoated reinforcing steel)

Each sample was 5 ft wide, 9 ft long, and 10 to 15 in. thick, depending on the thickness of the asphalt overlay remaining on the deck. Each sample was saw-cut from the given deck, chained through two pick holes, lifted out of the deck with a track hoe, and then placed on a trailer for delivery to the BYU Highway Materials Laboratory, where extensive testing was performed on each slab. Testing performed before the asphalt membrane-overlay systems were removed included electrochemical impedance spectroscopy and ground-penetrating radar surveys, which were conducted in collaboration with John McBride, presently Chair of the Department of Geological Sciences at BYU. After the asphalt membrane-overlay systems were removed, additional evaluations were performed on the bare concrete decks. These included visual inspection, hammer sounding, Schmidt rebound hammer testing, resistivity testing, halfcell potential testing, linear polarization testing, electrochemical impedance spectroscopy, cover depth measurement, and chloride concentration measurement. Each test was performed at 45 locations on each deck slab surface, contour maps showing spatial variability in each measured parameter were produced, and the data were then interpreted as required to satisfy the research objectives outlined for this research. In addition, selected slabs were subjected to intensive impact-echo testing in collaboration with Tadd Truscott and students in the Department of Mechanical Engineering.

Evaluation of the mentoring environment

The students involved in this project worked together with faculty from four different departments on campus, engineers with the Utah Department of Transportation and Raba- Kistner Infrastructure, construction managers with Provo River Constructors, and each other. Much of the field and laboratory work was accomplished in teams, and the crossdisciplinary interactions further enhanced the learning of each person. Overall, the students were able to apply classroom learning to their research tasks, teach each other about both the theory and operational characteristics of our testing equipment, and gain experience with data analysis and interpretation. Several students also participated with preparation of academic products based on the research findings.

List of students who participated and what academic deliverables they have produced or it is anticipated they will produce

This research involved 20 BYU students, including Noelle Anderson, Natasha Barrus, Paul Bartholomew, Bryan Blankenagel, Rachel Bytheway, Paul Dixon, Lisa Gurney, Jeff Hoki, Charles Hope, Randy Hurd, Jeffrey Klis, Christopher Leach, Sharlan Montgomery, Lizzie Nolen, Anjali Patil, Eric Sumsion, Kyle Sumsion, Tenli Waters, Joe Yaede, and Wanyang Zhang. The following academic products, including abstracts, conference proceedings, journal papers, and patents, have already resulted from this work:

1. Sumsion, E. S. Condition Assessment of Decommissioned Bridge Decks Treated with Waterproofing Membranes and Asphalt Overlays. M.S. thesis. Department of Civil and Environmental Engineering, Brigham Young University, Provo, UT, December 2013.
2. Patil, A. Delamination Detection in Concrete Using Disposable Impactors for Excitation. M.S. thesis. Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT, December 2013.
3. Mazzeo, B. A., A. N. Patil, R. C. Hurd, J. M. Klis, T. T. Truscott, and W. S. Guthrie. Air-Coupled Impact-Echo Delamination Detection in Concrete Using Spheres of Ice for Excitation. Journal of Nondestructive Evaluation, in press, 2013.
4. Mazzeo, B. A., A. N. Patil, J. M. Klis, R. C. Hurd, T. T. Truscott, and W. S. Guthrie. Numerical Simulations and Experimental Measurements of Steel and Ice Impacts on Concrete for Acoustic Interrogation of Delaminations in Bridge Decks. In Proceedings of the 40th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Baltimore, MA, July 2013.
5. Mazzeo, B. A., W. S. Guthrie, and A. N. Patil. Method and System for Structural Integrity Assessment. Patent Application No. 61778348, March 2013.
6. Mazzeo, B. A., A. N. Patil, and W. S. Guthrie. Acoustic Impact-Echo Investigation of Concrete Delaminations Using Liquid Droplet Excitation. NDT&E International, Vol. 51, October 2012, pp. 41-44.
7. Bartholomew, P. D., W. S. Guthrie, and B. A. Mazzeo. Vertical Impedance Measurements on Concrete Bridge Decks for Assessing Susceptibility of Reinforcing Steel to Corrosion. Review of Scientific Instruments, Vol. 83, No. 8, August 2012.
8. Mazzeo, B. A., W. S. Guthrie, and P. D. Bartholomew. Methods and Apparatus for Analysis of Concrete Cover in Reinforced Concrete Structures Subject to Reinforcement Corrosion. Patent Application Publication No. US 2012/0012470 A1, January 2012.
9. Bartholomew, P., B. Blankenagel, S. Guthrie, and B. Mazzeo. Impedance Spectroscopy of Concrete Cover on Bridge Decks with Reinforcing Steel. Abstract in Proceedings of the 2011 Annual Meeting of the Four Corners Section of the American Physical Society, Tucson, AZ, October 2011.

A minimum of two additional papers, one from each of the two M.S. theses cited in the list, and at least one more patent application are still expected.

Description of the results/findings of the project

A review of the bridge histories revealed that a waterproofing membrane had been installed on each of the bridge decks in 1984, meaning each waterproofing membrane had been in service for 26 or 27 years at the time of sampling. With the exception of one of the bridges, which was in good condition after 26 years of service, each of the bridge decks sampled had successfully served for at least 46 years. Aside from asphalt maintenance, no rehabilitation was needed on any of the bridge decks following installation of the waterproofing membranes. Without the application of the waterproofing membranes, the chloride concentrations in the bridge decks likely would have been much higher. Additional exposure to chloride ions from deicing salts would have quickly increased the chloride concentration in the concrete above critical levels, which would have led to significant corrosion of the reinforcing steel and premature bridge deck deterioriation. The research findings suggest that application of waterproofing membranes and asphalt overlays in a timely manner, before the accumulation of excessive amounts of chlorides within a deck, can be an effective approach for concrete bridge deck preservation.

While assessing the condition of a bridge deck can be performed using a variety of techniques, this research demonstrated the promise of two new technologies, including electrochemical impedance spectroscopy and impact-echo testing with disposable impactors, that offer specific advantages over existing procedures. Research focused especially on the use of water droplets for detecting shallow delaminations with impactecho testing was highlighted by BYU in a news release and subsequently by approximately 75 media outlets across the globe.

Description of how the budget was spent

Project funding was used primarily for student wages and supplies but also to transport the slabs from the bridge sites to campus for testing. Because Provo River Constructors donated the slabs, the expenses associated with removing the samples from the bridge decks were not charged to the project.