Shear versus flexural bond tests of Textile-Reinforced Mortar applied to masonry substrates

Abstract

The existing recommendations for the experimental investigation of the bond characteristics along interfaces comprising Textile-Reinforced Mortar (TRM) overlays and various types of substrates ignore the effect of out-of-plane stresses. This study investigates the in-plane and out-of-plane bond of two TRM systems with masonry substrate, employing the Single-Lap/Single-Prism (SL/SP) and the Modified Hinged Beam (MHB) set-up, respectively. The two systems shared the same cementitious matrix and comprised either Alkali Resistant (AR)-glass or carbon dry fibers textile (named GTRM and CTRM, respectively), while they had comparable axial rigidity. The failure mode of the specimens was due to slippage of the textile form within the matrix, regardless of the examined TRM system as well as the used set-up. Based on the comparison of the maximum textile axial stress obtained from the SL/SP and MHB tests for each TRM system, it was found that the normal stresses developed during bending enhanced the bond capacity of the CTRM system by almost 30%, whereas they had no apparent effect on the bond capacity of the GTRM system. The results of the current and previous related studies suggest that the bending stiffness, E_fibI_fib, of fibers is a parameter that could be correlated with the effect of the normal stress, in case dry fiber textiles are considered. Finally, it is concluded that for both adopted TRM systems the Cohesive Material Law calibrated based on the response curves obtained from the SL/SP and MHB tests is affected by the type of both the bond test and the textile’s fibers.