Effectiveness of concrete elements strengthening through PBO-FRCM confinement with various types of anchorage

This paper presents the results of experimental research on PBO (P-phenylene benzobisoxazole)-FRCM (fabric-reinforced cementitious matrix)- confined concrete elements with a variously shaped end PBO mesh overlap. In FRCM systems, the composite is bonded with the concrete using mortar as opposed to FRP (Fiober reinforced polymers) systems, and such bonding is effected using epoxy resin. Twelve confined concrete elements were tested. They were divided into four series, each comprising three elements. The elemnts were confined with a single layer of PBO mesh but differed in the shape (geometry) of the composite's end overlap. Thee results of the tests, during which the effect of the shape of the end mesh overlap on the values and distribution of transverse (circumferential) strains was examined, are presented. On this basis, an optimal way of constructing the PBO-FRCM confinement of concrete elements is proposed. The mimicking of the inner steel winding concept in the outer confinement made of PBO mesh turned out to be the most effective. The transfer of the ends of the overlap to the element's two ends also improves the load capacity of the support zones in which compressive stresses are concentrated.