Title:
Laser Shearography Applications in Concrete Durability Studies
Author(s):
Amde M. Amde, Richard A. Livingston, and John W. Newman
Publication:
Symposium Paper
Volume:
326
Issue:
Appears on pages(s):
94.1-94.10
Keywords:
concrete durability, delayed ettringite formation (DEF), exposure conditions, fine cracks, heat cycle, laser shearography, potassium content
DOI:
10.14359/51711077
Date:
8/10/2018
Abstract:
Laser shearography has shown a great potential for application in nondestructive testing (NDT) especially in the early detection of cracks in concrete. It records a sheared image of the speckle interferogram produced by illuminating an object with a laser. The objectives of the research were to evaluate the capability of laser shearography to detect fine early age cracks and to apply it to investigate possible differences in crack patterns between delayed ettringite formation (DEF) and freeze-thaw (FT) processes. It demonstrated that the laser shearography is capable of detecting fine cracks in early age concrete even when they are invisible to the naked eye (<10 μm). This provided quantitative information about trends in development of damage in concrete due to DEF or FT. The damage progressed over time by the propagation of the initial cracks rather than the appearance of new cracks which is consistent with the Holt and Janssen hypothesis. The density of cracks in the FT concrete specimens was greater than in those of the heat treated specimens and the rate of crack development was also faster, which is consistent with the Garboczi expansive stress model. Finally, increased potassium content accelerated the rate of crack development for both types of damage.
Related References:
1. Holt, E. and Janssen, D. "Influence of Early Age Volume Changes on Long-Term Concrete Shrinkage." Transportation Research Record: Journal of the Transportation Research Board, V. 1610, 1998, pp. 28-32.
2. Steinchen, W, and Yang, L., “Digital Shearography: Theory and Application of Digital Speckle Pattern Shearing Interferometry,” SPIE PRESS Monograph, Vol. PM100, Bellingham, WA, SPIE, 2003.
3. Yang, L, Chen, F, Steinchen, W, and Hung, M, Y., “Digital Shearography for Nondestructive Testing: Potential, Limitations, and Applications,” Journal of Holography and Speckle, V. 1, No. 3, 2005, pp.1-11.
4. Newman, J.W., Amde, A.M., Development of Prototype Compact Shearography System, Analysis Method and Software for Micro-Crack Detection, Contract Number DTRT57-08-C-10001. Washington, D.C.: FHWA, 2011.
5. Newman, J. W., “Holographic and Shearographic NDT Applications in Aerospace Manufacturing,” Materials Evaluation, V. 63, 2005, pp. 746-750.
6. Livingston, R. A., Newman, J. W., Ceesay, J. and Amde, A.M., “Development of a Portable Laser Shearography for Crack Detection in Bridges,” Al-Qadi and Washer, G. A (Eds.), NDE Conference on Civil Engineering, American Society for Nondestructive Testing, St. Louis, MO, 2006, pp. 262-268.
7. Amde, A. M, and Livingston, R., “Mitigation of Delayed Ettringite Formation in New and Old Concrete,”
4th World Conference on Applied Sciences, Engineering & Technology, Kumamoto University, Japan, 24-26 October 2015
8. Mehta, P.K. and Monteiro, P.J.M, Concrete: Microstructure, Properties and Materials, McGraw –Hill, New York, 2006.
9. Garboczi, E. J. "Stress, Displacement, and Expansive Cracking around a Single Spherical Aggregate under Different Expansive Conditions." Cement and Concrete Research V. 27 Issue 4: 1997, pp. 495-500.
10. Mehta, P. K., “Durability of Concrete – The Zigzag Course of Progress,” CANMET Conference on Durability of Concrete, Montreal, Canada, SP-234-1, May 2006, pp. 1-16.