PSI - Issue 78

Francesco Bencardino et al. / Procedia Structural Integrity 78 (2026) 1396–1403 Author name / Structural Integrity Procedia 00 (2025) 000 – 000

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• Kind of masonry, which can be either artificial masonry (clay bricks - BM) or a natural one (tuff units - TM); • Kind of mortar employed as a matrix in the FRCM system, which is the commercial mortar made of natural hydraulic lime (M1) or alkali-activated slag-based mortar (M2); • Kind of fabric in the FRCM system, i.e., basalt or steel; • Strengthening layout, since B-FRCM systems have been applied on only one (B1) or both sides (B2) of the masonry wall, while S-FRCM were always applied to both sides (S).

Table 1. Cyclic shear-compression test matrix.

Planned tests

Tests under investigation

Strengthening layout

Stone

Mortar

Fabric

Basalt Basalt

B2 B1

2 1 2 1 2 1 1 2 1 2 2 1 1 1

1 1 1 1 1

M1

Steel

S

Brick (BM)

Basalt Basalt

B2 B1

M2

Steel

S

-

Unreinforced specimen (BM-UR)

1

Basalt Basalt

B2 B1

- - - - - - -

M1

Steel

S

Tuff (TM)

Basalt Basalt

B2 B1

M2

Steel

S

Unreinforced specimen (TM-UR)

3. Cyclic shear-compression tests 3.1. Specimens and materials

Single leaf masonry walls tested under cyclic shear-compression tests were made of typical materials characterizing existing masonry buildings, which are clay bricks (255 x 120 x 60 mm 3 ), held together by an M5 lime-based mortar, arranged in joints with 10 mm thickness. The whole specimen dimensions were equal to 1310 x 255 x 1700 mm 3 , since they were provided with two reinforced concrete tie beams both in the upper (height equal to 200 mm) and lower part (height equal to 250 mm), due to practical reasons. The layouts of FRCM strengthening systems are shown in Fig. 1. The basalt textiles were coupled with both M1 and M2 mortars, while steel fabric only with M1; the matrix layers were 5 mm thick. As regards B-FRCM systems, the strengthening layout consisted of employing two basalt grids covering the whole wall façade which were overlapped for a length of 200 mm. Conversely, steel textile was arranged in vertical and horizontal strips characterized by a width of 100 mm and a total of 16 cords. Furthermore, four steel helical bars, which were blocked with a polypropylene element, were used as anchors aimed at improving bond between masonry substrate and external reinforcement. Concerning the mortar used for the FRCM system, M1 was a commercially available geopolymeric mortar consisting of natural hydraulic lime (NHL) and proprietary geobinder; compressive strength and elastic modulus stated by manufacturers were respectively equal to 15 MPa and 9 GPa (Kerakoll 2025). On the other hand, M2 mortar was composed of blast furnace slag, alkali-activated by means of sodium metasilicate powder and sodium carbonate mono hydrate; the complete mixture also comprised dried silica sand characterized by a particle diameter range equal to 0.1 1 mm. Mechanical properties were assessed by means of compression as well as flexural tests after 28 of curing; values of compressive and flexural strength respectively equal to 20.1 MPa (CoV=5.0%) and 2.2 MPa (16.0%) were found.