Diagonal Compression Behaviour of Masonry Walls Reinforced with FRM Coatings

In mortars used for strengthening of existing masonry walls the trend is toward the reduction of the thickness of the added external layers, but with a significant increase of the strength of the used FRM material (Fiber Reinforced Mortar). In the present analysis the focus is posed on some new lime mortar types which possess a very high strength in tension, although the elastic modulus remains in a normal range, in order to obtain a considerable toughness increase. The G-FRM system is composed with a glass fiber mesh that comply with this increased tensile resistance of the material, and this allow reducing the thickness of the reinforcing layers. A series of 12 diagonal compression tests of masonry walls reinforced with G-FRM has been completed in LISG Laboratory, comparing different FRM combinations. The walls were reinforced with three different lime mortar compounds with layer thicknesses of 12, 15 and 30 mm, on the basis of their nominal tensile strengths, and reinforced with three different glass fiber meshes. The performed tests showed that the interpretation of the observed behaviour needs a sound theoretical basis of the experimental setup, avoiding the simple analysis reported in standards and codes. A finite element model of the performed experiments was prepared, and an identification of the observed behaviour was carried out. As a conclusion, the G-FRM compounds were able to increase the load capacity of the walls more than 200% and demonstrated a very high bond with the masonry surface, reducing the need of transversal ties.