Diffuse ultrasound monitoring of stress and damage development on a 15-ton concrete beam.
This paper describes the use of an ultrasonic imaging technique (Locadiff) for the Non-Destructive Testing & Evaluation of a concrete structure. By combining coda wave interferometry and a sensitivity kernel for diffuse waves, Locadiff can monitor the elastic and structural properties of a heterogeneous material with a high sensitivity, and can map changes of these properties over time when a perturbation occurs in the bulk of the material. The applicability of the technique to life-size concrete structures is demonstrated through the monitoring of a 15-ton reinforced concrete beam subject to a four-point bending test causing cracking. The experimental results show that Locadiff achieved to (1) detect and locate the cracking zones in the core of the concrete beam at an early stage by mapping the changes in the concrete's micro-structure; (2) monitor the internal stress level in both temporal and spatial domains by mapping the variation in velocity caused by the acousto-elastic effect. The mechanical behavior of the concrete structure is also studied using conventional techniques such as acoustic emission, vibrating wire extensometers, and digital image correlation. The performances of the Locadiff technique in the detection of early stage cracking are assessed and discussed.
ISTerre, University Grenoble-Alpes & CNRS, BP 53, 38041 Grenoble Cedex 9, France.
Yuxiang
Y
Zhang
ISTerre, University Grenoble-Alpes & CNRS, BP 53, 38041 Grenoble Cedex 9, France.
Thomas
T
Planès
ISTerre, University Grenoble-Alpes & CNRS, BP 53, 38041 Grenoble Cedex 9, France.
Eric
E
Larose
ISTerre, University Grenoble-Alpes & CNRS, BP 53, 38041 Grenoble Cedex 9, France.
Anne
A
Obermann
IFSTTAR, 14-20 Boulevard Newton Cité Descartes, Champs sur Marne, 77447 Marne La Vallée Cedex 2, France.
Claude
C
Rospars
EDF R&D, 6 Quai Watier, 78401 Chatou, France.
Gautier
G
Moreau