PSI - Issue 64

Rebecca Grazzini et al. / Procedia Structural Integrity 64 (2024) 1532–1539 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1534

3

The mechanical properties of all the constituents were tested to characterize the FRCM systems. Regarding the glass fiber, both dry (D) and coated (C) fibers were tested through tensile tests according to (C.T. Centrale, 2019) to determine Young's modulus in traction and the tensile strength. For the mortars three-point bending and compression tests were performed according to (EN-1015-11, 2019). All the six FRCM composite systems were tested by means of single shear tests, denoted as Sst-X-Y, where X is the type of mortar (L, G, or C) and Y is the fiber condition (D for dry and C for coated). The tests were performed on brick supports, with a bond length of 220 mm and a width of 60 mm, and the push-pull configuration was employed, with a load applied under displacement control at a rate of 0.2 mm/min. The specimens were instrumented with three cantilever transducers to read the displacement of the brick, the fiber and the upper part of the mortar. 2.2. Test results The test results on mortars and textiles are presented in Table 1, showing mean values and coefficients of variation (CoV) for tensile and compression stress obtained from three-point bending and compression tests on the mortars and tensile stress and Youn g’s modulus for the textile. The load-displacement diagrams of the single shear tests are reported in Figure 1, where the displacement is the one read by the cantilever transducer on the fiber. It is possible to observe that in all the samples where the textile is dry, i.e., Sst-L-D, Sst-G-D and Sst-C-D, there is a remarkable deterioration of the cohesive law, due to the debonding of the textile. Conversely, this failure mode does not occur in the coated samples, which instead exhibit a progressive delamination after a linear-elastic phase, except for two cement specimens which fail immediately after the linear phase, reaching the maximum tensile stress of the fiber. As expected, the coating enabled reaching higher load values both at the end of the linear-elastic phase and at the peak load. Table 2 shows the maximum load Pmax and the corresponding displacement of the fiber s max . The displacement at the peak load of the coated samples is not reported because of the dispersion of the data caused by the different length of the delaminated parts of each specimen. The exploitation factor IF, which is the ratio between the tensile stress reached at the peak load of the test and the tensile strength of the fiber, is also reported. Table 1. Results of characterization tests on mortars and textiles, where: L=Lime; G=Gypsum; C=Cement for the mortars and D=dry; C=Coated for the textiles. Group n [MPa] E [GPa] mean CoV mean CoV Three-point bending - L 3 4.6 0.03 Three-point bending – G 3 6.5 0.03 Three-point bending – C 3 5.2 0.01 Compression - L 6 16.6 0.04 Compression – G 6 20.7 0.05 Compression – C 6 24.1 0.05 Textile traction - D 3 946 0.12 81.0 0.12 Textile traction - C 3 1419 0.10 96.2 0.07