A study of some factors affecting bond in cementitious fiber reinforced repairs

Concrete infrastructure repair remains a formidable challenge. We need to understand the repair performance and develop innovative materials and placement processes that lead to durable, cost-effective and esthetically pleasing repairs. In this context, fiber reinforced concrete is considered promising. The influence of fibers on the properties of the interface between old concrete and fiber reinforced repair remains poorly understood. This paper describes an experimental study on the influence of fibers on the mechanical properties of the interface. Bond strength was assessed by means of slant shear tests with different slants. Shear-normal stress interaction diagrams, adhesion strength and internal friction were obtained. Repair mortars with different contents of Polyvinyl Alcohol (PVA) fibers and the influence of wet dry cycles were investigated. Results show that PVA fibers added to the repair can significantly enhance interfacial adhesion. Once the repair interface is fully developed, fibers, however, do not mitigate damage from wetting and drying. (C) 2014 Elsevier Ltd. All rights reserved.