PSI - Issue 62

Paolo Zampieri et al. / Procedia Structural Integrity 62 (2024) 446–453 Paolo Zampieri/ Structural Integrity Procedia 00 (2019) 000 – 000

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The specimens without S.A. in this paper are named with the notation (R ∞ or R 1 or R 2 )_ l b _ Z_W, where Z is the specimen number, W denotes the type of fabric (I=impregnate fibre, D=dry fibre), and for the specimens with S.A. the notation is (R ∞ or R 1 or R 2 )_ lb _ (P c1 or P c2 )_ (L c1 or L c2 ) _Z_W. Specifically, when the insertion length l a equals b or b/2, the corresponding symbol is L c1 and L c2 , and if the number of S.A. n a equals 1 or 2, the equivalent symbol in the notation is P c1 and P c2 , respectively. Additionally, the notation "SG" is used if the specimen has strain gauges. Spike anchors were made of the same material of the dry fabric and were impregnated by hand over a length of approximately l a . After the curing of the masonry prims, the anchors were inserted in a pre-drilled hole (12 mm of diameter) filled with epoxy resin, then the first (internal) layer of matrix was applied to sandblasted surfaces corresponding to the bonded area (w b x l b ) and the reinforcement was inserted, the anchors were fanned out and then the second layer of mortar was applied. 2.2. Materials The fiber had longitudinal and transversal bundles spaced 17 mm furthermore, as illustrated in Fig. 2, the identical carbon reinforcement was employed in dry and pre-impregnated form, where the bundles are smaller in size as a result of the impregnation. The equivalent thickness of the textile in both directions was t f = 0.065 mm (mass density ρ =110 g/m 2 in both directions). The materials data are: • Average tensile strength and elastic modulus (ASTM D3039) of the dry fiber: tensile strength 1325 MPa (st.dev=101.13 MPa) and elastic modulus 208 GPa (st.dev=23.35 MPa); for the impregnated fiber: tensile strength 1944 MPa (st.dev=127.28 MPa) and elastic modulus 245 GPa (st.dev=25.47 MPa); • Matrix and hydraulic lime-based mortar compressive and flexural tensile strengths (UNI EN 1015-2-2007, at 28 days), for the matrix: compressive strength 31.69 MPa (st.dev=2.32 MPa) and flexural tensile strength 6.67 MPa (st.dev=0.73 MPa); and for the lime-based mortar: compressive strength 4.77 MPa (st.dev=0.51 MPa) and flexural tensile strength 1.85 MPa (st.dev=0.17 MPa); • Brick compressive strength (UNI EN 772-1:2015) is 42.51 MPa (st.dev=3.89 MPa). 2.3. Test setups In order to investigate the bond behavior of the carbon FRCM system, the masonry curved prism was tested with a direct shear test (single lap test) setup. The masonry prism was held in place in the test setup configuration by a steel frame, and two aluminium plates were attached to the end of the grid strip with epoxy resin. Finally, the gripping area was placed between two compressed steel plates and secured with eight through-bolts. Two linear variable displacement transducers (LVDTs), placed on the masonry surface, were used to measure the global slip of the loaded strip during the direct shear tests, which were carried out under displacement control at a rate of 0.15 mm/min (Fig. 2). Strain gauges were adhered to the core fiber bundles of many specimens.

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Fig. 2 Bi-directional carbon fiber fabric a) impregnated and b) dry and the entire test setup (c) including a picture of an actual specimen(d).