Experimental Qualification of PBO-FRCM Composites for Retrofitting Masonry Structures

This paper discusses the experimental qualification process of Fabric Reinforced Cementitious Matrix (FRCM) composites with Polyparaphenylene BenzobisOxazole (PBO) textiles. FRCMs consist of fiber textiles incorporated within inorganic cement or lime mortar matrices and have emerged as composite materials suitable for the retrofit of unreinforced masonry structures. The Italian Ministry of Infrastructures and Transportation and the European Organization for Technical Assessment have developed guidelines defining standard tests to certify the FRCM mechanical properties for qualification and acceptance purposes. This paper presents part of the experimental qualification results for PBO-FRCM composites with two PBO textiles (unidirectional and bidirectional) applied to two different masonry substrates (clay bricks and tuff blocks), considering tensile, bond and durability behavior. Direct tension tests were carried out on PBO textiles and FRCM specimens, with or without textile lap splices. Single-lap tests allowed determining the bond properties of both FRCMs on clay-brick and tuff-block masonry substrates. The stability of the tensile properties with respect to degradation induced by environmental actions was evaluated by performing direct tensile tests also on FRCM specimens conditioned in humid, saline, and alkaline environments, or subjected to high-temperature stress.