PSI - Issue 44

Giuseppe Bramato et al. / Procedia Structural Integrity 44 (2023) 2302–2309 Author name / Structural Integrity Procedia 00 (2022) 000–000

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A contrast frame was realized with two rigid steel plates (thickness of 30 mm). The load was recorded with a 100 kN load cell, while the slip between fabric and substrate was measured by two Linear Variable Displacement . In case of FRCM coupons, the deformations were measured with clip-on extensometers in direct mechanical contact with the specimens by knife edges positioned at the gauge length (=100 mm). In both cases test speed was set equal to 0.2

mm/min (displacement control). 3. Materials characterization

The Basalt open mesh grid was characterized according to dei Lavori Pubblici, C. S. (2018) by tensile test on specimens with the same dimensions of the fabric used for FRCMs (100x600 mm) (Fig. 4a). Even in this case steel tabs were applied at the ends to prevent the failure in the grip area. The obtained results were 1312 ± 55 MPa, 0.019 ± 0.001 and 68 ± 1.77 GPa for the tensile strength, maximum strain and Young’s modulus, respectively. The values are slightly lower than that reported in manufacturer technical sheet in case of tensile strength and Young’s modulus (1602 MPa and 89 GPa, respectively), while is similar in case of maximum strain (0.018).

(a) (c) Fig. 4. Materials characterization: (a) tensile test on dry fibre, (b) three-point bending test on mortar specimens, (c) compression test on mortar coupons The inorganic matrixes were characterized according to E. UNI, 1015-11 (2007). For each mortar, a triplet of 40x40x160 mm were casted in steel formwork and cured at laboratory environmental conditions (i.e. ~23 ± 2 °C, ~50 ± 5 % RH) for 28 days. Each prism was tested in bending (Fig. 4b) and then, when the flexural crack opened, the two parts of the sample were testes in compression by considering 40x40x40 mm coupons (Fig. 4c). The obtained results were 8.73 ± 0.34 MPa and 39.98 ± 2.88 MPa for the cementitious mortar flexural strength and compressive strength, respectively; 6.29 ± 0.39 MPa and 15.98 ± 1.17 MPa for the lime-based mortar flexural strength and compressive strength, respectively. In both case the values respect what reported in manufacturer technical sheets. In fact, the suggested lime-based mortar compressive after 28 days is higher than 15 MPa, while the suggested cementitious compressive and flexural strength after 28 days are higher than 25 MPa and 8 MPa, respectively. (b)

(a) (b) Fig. 5. Stone characterization: (a) compression test on 70x70x70 mm specimens, (b) three-point bending test on 50x50x300 mm coupons The substrates were characterized by three-point bending flexural test on 50x50x300 mm specimens (Fig. 5) - according to UNI EN 12372 (2007) - and compression tests on 70x70x70 mm coupons – according to UNI EN 1926 (2007). The obtained results were 2.89 ± 1.19 MPa and 15.77 ± 1.55 MPa for the Pietra Leccese substrate flexural strength and compressive strength, respectively; 3.18 ± 1.25 MPa and 11.86 ± 0.58 MPa for the Calcarenite substrate flexural strength and compressive strength, respectively. In this case the technical sheet are missing but the results seems to be reliable with the typical mechanical performance of these materials.