Published: Jan 1995
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Brittle cementitious composites are subjected to forces or loads which cause cracking and a potential reduction in material performance. They are, for the most part, heavily reinforced to have fracture tolerance.
The subject of this research is the enhancement of flexural toughening beyond that available in an original hardened material by the release of “healing” chemicals such as adhesives from hollow fibers into cementitious matrices in response to loading. Thus, the sensing of a crack by the fibers or the breaking of coating starts the activation of a remedial process (i.e., the release of a sealing or adhering chemical). This capacity for self-healing occurs whenever and wherever cracks are generated.
In terms of fracture mechanics, this research concerns the repair of cracks and rebonding of fibers by chemicals released from hollow fibers at the fiber wall and into the adjacent cracks. The overall property change is an increased flexural toughening. The mechanisms for that appears to be an adhesive rebonding of the fibers and a crack-filling with adhesives which behave more rigidly when bonded inside cracks.
repair cracks, rebond fibers, flexural toughening, time release, fracture, toughness
Professor, School of Architecture, University of Illinois, Champaign, IL