Interface experimental behavior between basalt-FRCMs and natural stones

The issue of environmental sustainability is central to several areas of research; in fact, the reduction of polluting emissions and concentration of CO2 in the atmos- phere is a key objective for both private and public institutions. In structural engineering, the sustainability goal involves the design stage, the construction technologies and materials, the maintenance. Specifically referring to structural materials, the research effort is very relevant, as the production of many materials currently used is particularly energy intensive. In the last years, innovative materials have been developed by replacing some components with recycled ones or from industrial processing waste. For example, innovative geopolymer mortars are made with lightweight components, blast furnace or fly ashes (a residue from coal combustion in electricity generation) that replace traditional binder. This new kind of materials can be used as inorganic matrix in case of FRCM (Fiber Reinforced Cementitious Matrix) applica- tions to restore and strengthen existing buildings. The object of the experimental campaign, whose results are reported in this paper, is to study the shear-bond behavior between basalt- FRCM reinforcement system and masonry varying the binder in the mortar: two traditional (cement and lime-based, both with short fibers inside) and an innovative geopolymer matrixes. Two different types of substrates representative of the historical and artistic heritage of South- ern Italy are also used: a compact calcareous stone, called Pietra Leccese, and a porous calcar- eous stone, called Calcarenite. The results obtained evidenced that the mechanical properties of inorganic matrix always influence the shear bond behavior of the samples, similar conclu- sion cannot be drawn referring to the mechanical properties of substrates.