## 3 Results and Discussion
### FRAAM Composite: Mechanical Behavior
To highlight how the alkali-activated matrix affects the tensile behavior of the strengthening system, the major outcomes of the composites tested in the present work and those obtained by testing an available commercial system based on the same basalt textile [14] are summarized in Table 5. In particular, the commercial mortar used in [14] was the Mineral-Natural Hydraulic Lime (NHL), whose main properties are reported in Table 3.  
Figure 14: (**A**) Tensile test: crack pattern (end of stage II); (**B**) yarn transversal section; (**C**) waviness of the warp yarn. In region I, the mortar significantly contributes to both the stiffness and the load-bearing capacity of the composite. The use of the mineral-NHL mortar in place of alkali-activated mortar leads to a reduction of the tensile modulus of elasticity \(\mathrm{E_{I}}\). The higher \(\varepsilon_{\mathrm{I}}\) scattering observed for the basalt FRAAM can arise from the lower dimensional stability of alkali-activated mortar than the commercial mineral-NHL mortar. The stress \(\sigma_{\mathrm{L,m}}\) was calculated by dividing the load corresponding to the first mortar cracking by the cross-sectional area of the specimens. Stress values \(\sigma_{\mathrm{I,m}}\) obtained for both composites are lower than the estimated mean tensile strengths of their plain mortars. This can be attributed to the occurrence of matrix cross-sectional areas that are unsymmetrical and reduced due to the waviness of warp fibers bundles and the presence bonded joints. The ultimate stress, strain and tensile modulus of elasticity in region III and the exploitation ratio are similar in the two systems, as the load, in region III, is borne by the reinforcement in the cracked area of the specimen. The single lap direct shear test, in a push-pull configuration, was used to study shear debonding of FRAAM to masonry substrate. The composite-to-substrate bond strength represents a fundamental information to evaluate the effectiveness of the externally bonded reinforcements. The results of the single-lap shear tests in terms of load-global slip response curves and main numerical results are reported in Figure 15 and Table 6 respectively. In particular, peak stress was calculated according to Equation (2) and the exploitation ratios were calculated as follows:  
Exploitation ratio [vs. textile] = \(\sigma_{\mathrm{max}}\)/\(\sigma_{\mathrm{f}}\)  
Exploitation ratio [vs. tensile] = \(\sigma_{\mathrm{max}}\)/\(\sigma_{\mathrm{u}}\)  
where:  
\(\sigma_{\mathrm{max}}\) = peak stress  
\(\sigma_{\mathrm{f}}\) = textile tensile strength  
\(\sigma_{\mathrm{u}}\) = average composite ultimate tensile strength  
In the load-slip response curve of the basalt FRAAM, several slight load drops occur. These can be associated with an interfacial longitudinal crack along the fabric and the transversal cracks on the external matrix layer formed and developed during the test. This cracking is originated by the slippage of the fabric at the internal matrix layer interface as a consequence of the interfacial shear stress increasing. Since the external matrix layer is bonded to the reinforcement fabric, it translates with the slipped fabric. Similar behavior has been found when lime mortars are used as matrix to prepare FRCM composites, whereas when Portland cement is used only one crack often develops [48]. Average peak load around 1148 N and global slip around 6 mm were measured.