Fabric-reinforced cementitious matrix behavior at high-temperature: Experimental and numerical results

The use of externally applied composite systems to upgrade, strengthen or rehabilitate masonry or concrete structures is well established. However, structural strengthening with organic type composites, such as fiber-reinforced polymer (FRP) systems, may be impractical when the element is exposed to high-temperature service conditions, due to significant degradation of the organic resin. Instead, the use of an inorganic matrix, as in the case of fabric-reinforced cementitious matrix (FRCM) composites, may overcome this problem. The purpose of this study is to evaluate the mechanical behavior under high-temperature conditions of FRCM systems. Different FRCM composites are evaluated and include carbon fabrics ranging from dry to highly-impregnated with an organic resin. The experimental spectrum is comprised of uniaxial tensile and double-shear bond tests performed under temperatures ranging from 20 to 120 °C to determine the influence of temperature over the FRCM mechanical properties. Furthermore, SEM analysis was used to study the damage processes at the fiber-matrix interface post tensile testing. Experimental results show variations in the FRCM mechanical properties if tested at high temperature conditions (caused by the deterioration of the resin coating at the interface fiber-matrix) while residual performance after exposure to elevated temperatures remains unchanged. FRCM reinforced with dry fabrics has proven not to be affected by temperatures up to 120 °C. A numerical model using a fracture variational approach, based on incremental energy minimization, was also developed to simulate the FRCM behavior in double shear tests under different temperatures exposition.