Tensile and bond properties at elevated temperatures of a PBO-FRCM composite system for strengthening concrete elements: Experimental and analytical investigations.

This paper presents experimental and analytical investigations on the tensile and bond behaviour at elevated temperature of a polypara-phenylene-benzo-bisthiazole (PBO) fabric reinforced cementitious matrix (FRCM) system for strengthening concrete elements. Direct tensile (DT) and single lap direct shear tests (DS) were performed under steady-state conditions at the following temperatures: 20 °C, 85 °C, 150 °C, 230 °C and 300 °C. The results obtained were evaluated in terms of strength, stiffness, ultimate strain, load vs. slip response at the interface PBO FRCM/concrete and failure modes. Overall, the tensile and bond properties were significantly affected by the temperature increase. These results are mainly associated with the reductions of mechanical properties of the FRCM constituent materials as well as the degradation of the interaction between the fibres and the inorganic matrix at elevated temperatures. The experimental results were then used (i) to evaluate the suitability of the Aveston–Cooper–Kelly (ACK) model in describing the tensile response of FRCM at elevated temperatures and (ii) to calibrate temperature-dependent local shear bond stress vs. slip laws for the FRCM-concrete interaction. • PBO fibres, mortar, PBO FRCM coupons and PBO FRCM-to-concrete joints exposed to temperatures ranging from 20°C to 300°C; • Steady-state mechanical properties determined at : 20°C, 85°C; 150°C; 230°C and 300°C; • Results obtained evaluated in terms of strength, stiffness, ultimate strain, shear stress and slip; • Assessment of the Aveston-Cooper-Kelly model in describing the tensile response of the PBO FRCM at elevated temperatures. • Parameters of the local shear bond stress vs slip laws calibrated using 1 1 It is important to note that due to the proprietary nature of the patented product used herein, detailed information regarding its composition is not available. the experimental results. [ABSTRACT FROM AUTHOR]