Experimental investigation on a FRCM bio-composite for sustainable retrofitting of masonry buildings

Strengthening masonry structures by using green and natural materials has received increasing attention. Natural fibers can be obtained from vegetables, animals or mineral sources and can be used to meet modern buildings safety standards and to reduce carbon dioxide emissions. This paper presents a novel method to strengthen masonry buildings through the application of a mortar coating reinforced with natural fibers made of a jute or a basalt grid. This class of materials is known as Fiber Reinforced Cementitious Matrix (FRCM). FRCM composites can produce an increment in the mechanical properties of masonry members and contribute to the thermal-acoustic insultation of the building envelope. The mortar coating is made of a hydraulic lime: to increase thermal properties this was admixed with short spelt fibers. Both matrix (lime mortar) and fibrous material were initially mechanically and thermally characterized. Laboratory tests have been carried out to study the bond characteristics between the FRCM composite and brickwork masonry. It was found the low mechanical properties of jute fibers are aggravated by a low FRCM-to-masonry bonding, making difficult to use this material for structural retrofit. On opposite, basalt fibers exhibit high mechanical properties and their use in conservation is surely promising and interesting.