Behavior and modeling of strengthened three-leaf stone masonry walls

The application of three different intervention techniques on three-leaf rubble stone masonry walls are discussed here. Injections, repointing, and the placing of ties connecting the two external whytes were considered, both singularly and in combination. Lime-based products were chosen for injection grouts and repair mortars, to ensure better compatibility with the original materials. The experimental tests, performed on seventeen large scale samples under compressive loads, showed that: (i) injections are very effective to improve the mechanical characteristics of the walls; (ii) the other techniques have less influence on the strength but can operate in avoiding ‘brittle’ failure modes (ties placing) and in improving the durability of the masonry (repointing); (iii) the combination of the techniques ensures the enhancement of the global behavior of the walls. The integration of the experimental results with data available in literature allowed the calibration of an analytical model able to predict the compressive strength of injected walls, based on parameters given by simple experimental tests.