Bond Behavior of Yarn and Textile Pull-Out Tests in FRCM Systems

The behavior of inorganic matrix fiber-reinforced composites is mainly conditioned by the fiber-matrix interface bond, which in turn depends on the characteristics of the mortar (primarily aggregate granulometry and type of binder) and the fiber textile (primarily material stiffness, yarn type, knot effectiveness, and textile amount and dimensions). To investigate the factors influencing the fiber-matrix bond, in this study, an extensive experimental investigation was conducted, using different test setups to perform the pullout of the standalone yarn and of the textile. In particular, different FRCM systems composed of fiber-glass open textiles coupled with a lime and cement matrix are investigated through single shear tests (SST), textile pull-out tests on composite lamina specimens (TPT), and multifilament pull-out tests on composite lamina (MPT). Moreover, characterization tests on the standalone constituents were carried out, comprising also grain size analysis of the aggregates of the two considered matrix mortars. The results of SST, TPT, and MPT were compared and commented, also considering the different characteristics of the two matrix mortars.