Lime-based plasters reinforced with hemp meshes for retrofitting masonry structures

Abstract

The recent earthquakes in the Mediterranean area provoked serious damages and collapses to the built-up, including masonry buildings that represent the highest percentage of existing structures. The protection of the historical heritage to prevent economic and human losses is always accompanied by the compelling need of preserving the environment due to the increasing attention to the sustainability issue. In this framework, retrofit solutions already widespread and effective in the Seismic Engineering field can also be improved from an environmental point of view. In past years, one of the techniques most applied to masonry structures is the Fiber Reinforced Cementitious Matrix (FRCM), that is usually made of artificial fibres, such as steel, carbon, and glass, immersed into a matrix used to fix the reinforcing system to the structural support. The sustainability of this reinforcement kind can be improved by replacing artificial fibres with natural ones, such as hemp, that claims good mechanical properties and is carbon negative. The research aims at experimenting a retrofitting system, called Hemp-FRCM, that is made of a hemp mesh drowned in a lime matrix. The hemp fibres are preliminary subjected to tensile tests. Then, the Hemp-FRCM system is applied to a brick masonry wall tested under compressive loads. Finally, the adhesion capacity of the system to a Neapolitan yellow tuff support is evaluated by performing delamination tests. The experimental campaign shows promising results on the use of hemp meshes instead of artificial systems for the structural retrofit of existing masonry buildings.