Detecting the Activation of a Self-Healing Mechanism in Concrete by Acoustic Emission and Digital Image Correlation

Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

[1]  Jin-Guang Teng,et al.  Bond-slip models for FRP sheets/plates bonded to concrete , 2005 .

[2]  M. Elices,et al.  The cohesive zone model: advantages, limitations and challenges , 2002 .

[3]  Masayasu Ohtsu,et al.  Acoustic Emission Testing , 2006, Advanced Materials Research.

[4]  N. Belie,et al.  Self-healing of cracks in concrete , 2011 .

[5]  G. Paulino,et al.  Concrete fracture prediction using bilinear softening , 2007 .

[6]  Hubert W. Schreier,et al.  Image Correlation for Shape, Motion and Deformation Measurements: Basic Concepts,Theory and Applications , 2009 .

[7]  D. Aggelis.  Classification of cracking mode in concrete by acoustic emission parameters , 2011 .

[8]  P. Bowen,et al.  Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment , 2011 .

[9]  T. Shiotani,et al.  Acoustic Emission and Ultrasound for Damage Characterization of Concrete Elements , 2009 .

[10]  Jialai Wang,et al.  Cohesive zone model of intermediate crack-induced debonding of FRP-plated concrete beam , 2006 .

[11]  Masayasu Ohtsu,et al.  Crack classification in concrete based on acoustic emission , 2010 .

[12]  Matz Modéer,et al.  A fracture mechanics approach to failure analyses of concrete materials , 1979 .

[13]  N. De Belie,et al.  Visualization Of The Healing Process OnReinforced Concrete Beams By Application OfDigital Image Correlation (DIC) , 2012 .

[14]  T. Matikas,et al.  Investigation of different fracture modes in cement-based materials by acoustic emission , 2013 .

[15]  Nele De Belie,et al.  Acoustic emission analysis for the quantification of autonomous crack healing in concrete , 2012 .

[16]  M. Ohtsu.  Recommendation of RILEM TC 212-ACD: acoustic emission and related NDE techniques for crack detection and damage evaluation in concrete* Test method for classification of active cracks in concrete structures by acoustic emission , 2010 .

[17]  Kim Van Tittelboom,et al.  Self-Healing Concrete through Incorporation of Encapsulated Bacteria- or Polymer-Based Healing Agents ('Zelfhelend beton door incorporatie van ingekapselde bacteri , 2012 .

[18]  Rilem.  Determination of the fracture energy of mortar and concrete by means of three-point bend tests on notched beams , 1985 .