Distributed damage in concrete is associated with microcracking due to delayed ettringite formation (DEF), alkali silicate reaction or freeze thaw (F-T) cycles. A possible metric for quantifying this type of damage by ultrasonic NDT is the Q factor, which is the ratio of the resonant frequency to the damping factor. The Q factor is readily obtained from the width of the resonant frequency peak in the frequency spectrum. Laboratory specimens of concrete were prepared and subjected to either DEF favorable conditions or freeze-thaw cycling for up to 220 days. The frequency response of the samples was measured using ASTM C597-95 “Standard Specification for Pulse Velocity Measurements in Concrete”. The F-T samples showed a significant decrease in Q with increasing cycles, however, the DEF specimens showed either no correlation with expansion, or a positive one indicating that concrete strength actually increased with time. Further analysis of the Q-factor showed that the damping factor does not correlate with damage in either case. This is apparently because the damping is dominated by the hydrated cement paste, which is not significantly affected by the DEF or F-T processes. Consequently the changes in the Q factor are the result of reductions in the resonant frequency. The conclusion is that microcracking is a significant mode of damage for F-T but not for DEF. This is consistent with theoretical models of the difference in the distribution of internal stresses between the two types of damage.
1. Kesner, K., M.J. Sansalone and R.W. Poston, "Detection and Quantification of Distributed Damage in Concrete
Using Transient Stress Waves". ACI Materials Journal, 2004. 101(4): p. 318-326.
2. Livingston, R.A., C. Ormsby, A.M. Amde, M. Ceary, N. McMorris and P. Finnerty, "Field Survey of Delayed
Ettringite Formation Related Damage in Concrete Bridges in the State of Maryland", in Seventh CANMET/ACI
Conference on Durability of Concrete, SP-234, V.M. Malhotra, Editor. 2006, American Concrete Institute:
Montreal, CANADA. p. 251-268.
3. Malhotra, V.M. and V. Sivasundaram, "Resonant Frequency Methods", in Handbook on Nondestructive Testing
of Concrete, V.M. Malhotra and N.J. Carino, Editors. 2004, CRC Press: Boca Raton, FL. p. 7-1 to 7-18.
4. Clarke, S.L., Improved Method for Non-destructive Testing of Concrete Prisms, MS Thesis, Mechanical
Engineering Dept., University of Washington, Seattle, 1991.
5. Janssen, D. and M. Snyder, Resistance of Concrete to Freezing and Thawing, SHRP-C-391. 1994, Strategic
Highway Research Program, National Research Council,: Washington D.C.
6. ASTM, "ASTM C 666 Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing", in
Annual Book of ASTM Standards: Volume 04.02 Concrete and Aggregates. 2008, ASTM International: West
Conshohocken, PA.
7. ASTM, "ASTM C 215 - 08 Standard Test Method for Fundamental Transverse, Longitudinal, and Torsional
Frequencies of Concrete Specimens", in Annual Book of ASTM Standards: Volume 04.02 Concrete and
Aggregates. 2008, ASTM International: West Conshohocken, PA.
8. McMorris, N., Linear and Non-Linear Frequency Domain Techniques for Processing Impact Echo Signals to
Evaluate Distributed Damage in Concrete, PhD Dissertation, Civil Engineering Dept., University of Maryland,
College Park, MD, 2009.
9. Becker, J., L.J. Jacobs and J. Qu, "Characterization of Cement-Based Materials Using Diffuse Ultrasound".
Journal of Engineering Mechanics, 2003. 129(12): p. 1478-1484.
10. El-Korchi, T., D. Gress, K. Baldwin and P. Bishop, "Evaluating the Freeze-Thaw Durability of Portland
Cement-Stabilized-Solidified Heavy Metal Waste Using Acoustic Measurements", in Environmental Aspects of
Stabilization and Solidification of Hazardous and Radioactive Wastes. ASTM STP 1033, , P.L. Cote and M.
Gilliam, Editors. 1989, American Society for Testing and Materials: Philadelphia. p. 184-191.
11. Aggelis, D.G., "Damage Characterisation of Inhomogeneous Materials: Experiments and Numerical
Simulations of Wave Propagation". Strain, 2011. 47(6): p. 525-533.
12. Khong, H., A.M. Amde, J. Ceesay, R.A. Livingston and J.W. Newman." Application of laser shearography for
detecting microcracking in concrete". in Recent Advances in Concrete Technology. 2007. Washington, DC:
DEStech. p. 175-184.
13. Garboczi, E.J., "Stress, Displacement, and Expansive Cracking Around a Single Spherical Aggregate Under
Different Expansive Conditions". Cement and Concrete Research, 1997. 27(4): p. 495-500.