## 2 Literature Review
A result of significance, especially for historical masonry structures, is the observed satisfying behavior of anchors bonded to masonry through lime-based grout, compatible with the original materials. Investigations performed by [PERSON] et al. [9] and [PERSON] et al. [10] focused on the behavior of different types of anchoring systems (chemical, cementitious grout, and mechanical) installed in stone and solid clay brick masonry. The aim of the work was to identify the most efficient system for use in masonry strengthening applications. Unconfined monotonic pull-out tests were performed on anchors installed in uncracked wall specimens made with granite stones (compressive strength 68.7 MPa) and lime-based mortar (f\({}_{\text{mc}}\) = 1.63 MPa) or solid clay brick walls (brick compressive strength 19.9 MPa and mortar f\({}_{\text{mc}}\) = 1.4 MPa) under a compressive strength of 0.2 MPa. Metallic fasteners (diameter d = 10 mm) were used with an embedment depth of 150 mm (for chemical and grouted anchoring systems) or 85 mm (for mechanical anchorage). The anchors were installed in the central area of the wall specimens, away from the edges, in stone units, or in the middle of stretcher brick (200 mm \(\times\) 65 mm \(\times\) 95 mm), as appropriate. The cases of anchors perpendicular or inclined with respect to the wall face were investigated. The anchors bonded to masonry exhibited better behavior than those mechanically anchored to the substrate. Finally, anchors embedded in stones exhibited slightly higher tension resistances than their counterparts installed in clay bricks. Several experimental campaigns focused on anchor applications, such as strengthening the connection of walls at corners of heritage buildings, using steel anchors. In this framework, [PERSON] and [PERSON] [11] studied the behavior of grouted anchors under monotonic and repeated tension loading. The monotonic tests were performed on anchors installed in masonry wallettes, having an L-shaped cross-section, while the repeated tests were performed on anchors to masonry panels of a T-shaped cross-section. In both cases, the walls were made of solid clay bricks and lime-based mortar. For the installation of the 16 mm anchors at a depth equal to 350 mm, a hole of 80 mm in diameter was drilled, and a cement-based injection mortar was used in combination with a fabric sleeve. The anchor locations were randomly selected and at least one mortar joint was included in the drilled core. The purpose was to involve more than one brick, thus avoiding the pull-out of a single brick unit. Six unconfined monotonic pull-out tests were performed with a simultaneous application of compressive stress on the wall. In the case of L-shaped walls, this stress was equal to 0.07 MPa (three tests) or 0.70 MPa (three tests), while in the three cyclic tests on T-shaped walls, the compressive stress was equal to 0.08 MPa. The measured tension resistances of the anchors were almost 70% higher than anticipated, based on calculations, while they seemed to be insensitive to the value of the compressive stress applied on the wall. This was mainly attributed to the development of mechanical locking between the anchor and the wall due to the presence of the fabric sock. [PERSON] et al. [12] have studied the behavior of grouted anchors under monotonic or repeated tension load. The tests aimed at acquiring data on the use of grouted anchors in applications, namely, the connection of masonry panels (T and L connections). The wall specimens were made of solid clay bricks and lime-based mortar of low compressive strength (0.42 MPa), representative of historic masonry. The anchors were installed in masonry including brick and joint areas using three injection mortars, namely, two cement-based mortars (compressive strength: 49.2 MPa and 59.1 MPa, respectively) and one lime-based (compressive strength: 9.3 MPa), all of them in combination with a polyester fabric sleeve.