Evaluation of the self-healing effect in cement-based materials with embedded cementitious capsules by means of Acoustic Emission techniques

Due to its low tensile strength and the presence of defects brought on by improper construction methods or other factors, cracks in concrete are practically inevitable. For reinforced-concrete structures, even if cracks do not necessarily increase the risk of collapse, they unquestionably hinder aspects such as service life. Self-healing cementitious materials have been developed because of growing concern for the security and sustainability of structures. For these new materials to be used in actual structures, it is essential to conduct research into the self-repair effect that they may offer, and possibly quantify it directly on-site, by means of non-destructive methods. In this sense, the objective of this work is to use Acoustic Emission (AE) analyses to non-destructively characterise the response of an autonomic capsule-based system, as a function of the specific polymeric healing agents contained in the capsules. Comparisons will be made between the reference and selfhealing specimens, and between the different self-healing specimens themselves, through the analysis of such parameters as the ultimate load, absorbed fracture energy, and emitted Acoustic Emission (AE) energy. Such type of analysis can give valuable insights not only on quantitative but also on qualitative aspects (such as the level of brittleness or ductility introduced by the specific self-healing system adopted) in view of possible applications in real structures.