Analytical modelling bond behaviour of polybenzoxazole (PBO) and glass Fibre Reinforced Cementitious Matrix (FRCM) systems coupled with cement and gypsum matrixes: Effect of the Cohesive Material Law (CML) shape

The trilinear Cohesive Material Law (CML) is generally employed to analyse fibre-matrix interface behaviour of Fibre Reinforced Cementitious Matrix (FRCM) systems regardless of their specific features. In this study, four laws, all ending with a frictional plateau, are selected to uncover suitability with characteristics of different FRCM systems. Closed form expressions of the local slip law for the different CMLs are derived for short and long bonded lengths. Then, adhesion tests of polybenzoxazole (PBO) -cement and glass-gypsum systems are considered to implement consistent comparisons. Results suggest that laws providing linear softening well represent the analysed cement-PBO system, while for the glass-gypsum system, a slower degradation of bonding occurred and a different CML (trapezoid shaped) estimates more effectively experimental curves.