RETICOLA PLUS – Reinforced pointing of the mortar joints on the exposed wall and the application of reinforced plaster with preformed GFRP meshes on the opposite wall – Teramo

The small medieval village of Montegualtieri in Abruzzo, in the province of Teramo, stands with an oval plan on a hill with the characteristics of a promontory overlooking a bend of the Vomano River. A triangular tower, built around the 14th century on a rocky spur and reinforced with brick buttresses, characterizes the entire structure, serving as a guardian of the valley.

Always privately owned, the village underwent redevelopment works that allowed its revival by the Province in 1976, following the death of the last heir of the owning family. In the central area of the village, adjacent to the medieval tower, stands the building that was the subject of intervention and suffered significant structural damage following the earthquake of 2009.

DESCRIPTION The building has a load-bearing structure made of irregular mixed stone masonry with a foundation grid connected to the perimeter walls. Studies conducted have not allowed for the determination of the building’s construction period. The analysis of the building and its structural characteristics formed the basis for the choices of seismic improvement and repair following the damages caused by the 2009 earthquake. In particular, the structural analysis of the overall behavior of the building allowed for the identification of not only the causes but also the mechanisms activated by the earthquake.

The preservation of the exposed stone masonry was a fundamental constraint in the development of the project.

FIBRE NET SYSTEM The need for masonry consolidation and the aesthetic considerations related to the presence of an exposed masonry wall found their synthesis in the application of the FIBREBUILD RETICOLA PLUS system. This solution combines the RETICOLATUS system, specific for exposed facades made of stone or brick, with the technique of reinforced plaster with a glass fiber-reinforced polymer (GFRP) mesh.

The system consists of reinforced pointing of the joints, which involves inserting a continuous network of stainless steel wire meshes into the mortar joints. The nodes of the wire meshes are fixed with transverse metal bars attached to the masonry. The small dimensions of the wire meshes allow for easy bending as needed to facilitate passage through the joints and between the various stone elements that make up the masonry. Since the wire meshes are flexible and pass through the dovetail anchors of the transverse metal bars without being solidly connected to them, they can be placed inside the masonry joints regardless of their direction. The mesh size depends on the size of the stone elements and should not exceed the thickness of the masonry (typically, the mesh spacing is between 40 and 60 cm, and the connections are about 4 per square meter). The arrangement of the connectors follows an irregular pattern determined by the position of the nodes of the stainless steel wire mesh. The connector has a ring-shaped end through which the metal wires pass. By tightening the nuts on the threaded bars, the wires can be tensioned, resulting in beneficial effects.

The masonry reinforced with the Fibrebuild Reticola Plus system allows for:

• Generalized improvement of mechanical characteristics, in terms of compression resistance, shear resistance, and bending resistance for actions in the plane and orthogonal to the installation plane.
• Effective connections between contiguous masonry elements, such as at corners or intersections, which provide resistance against out-of-plane overturning mechanisms.
• Transverse connections between masonry faces through the steel bars that act as artificial diatonic elements, providing monolithic behavior to the panel.

The use of the FIBREBUILD RETICOLA PLUS system has thus achieved the objectives of seismic improvement while preserving the characteristics of the exposed masonry wall. At the same time, it has demonstrated ease and speed of application, resulting in a reduction in overall intervention costs.

CONSTRUCTION DETAILS PROJECT_Measures for seismic improvement and repair following damages from the 2009 earthquake