Strengthening Masonry Arches with Lime-Based Mortar Composite

Abstract

In recent decades, many strengthening interventions on masonry elements were performed by using fiber reinforced polymers (FRPs). These advanced materials proved to be effective to increase the load-carrying capacity of masonry elements and to improve their structural behavior, avoiding the most critical failure modes. Despite the advantages of this technique compared to more traditional methods, FRP systems have disadvantages related to their low resistance to high temperatures, impossibility of application on wet surfaces, low permeability, and poor compatibility with masonry supports. Therefore, composite materials made of a fiber textile embedded in an inorganic matrix were recently proposed as alternatives to FRPs for strengthening historic masonry constructions. These composite materials are easier to install, have higher resistance to high temperatures, and permit higher vapor permeability than FRPs. The inorganic matrix is frequently a cement-based mortar, and the composite materials made of a fiber textile embedded in a cement-based mortar are usually identified as FRCM (fabric reinforced cementitious matrix) composites. More recently, the use of natural lime mortar as an inorganic matrix has been proposed as an alternative to cement-based mortars when historic compatibility with the substrate is strictly required, as in case of restoration of historic buildings. In this paper, the effectiveness of a fabric made of basalt fibers embedded in lime mortar matrix (Basalt-FRLM) for the strengthening of masonry arches is investigated. An experimental investigation was performed on 1:2 scaled brick masonry arches strengthened at the extrados with a layer of Basalt-FRLM and tested under vertical load. The results obtained are compared with previous results obtained by the authors by testing masonry arches strengthened at their extrados with FRCM and FRP composites. This investigation highlights the effectiveness of Basalt-FRLM in increasing load-currying and the displacement capacities of masonry arches. The Basalt-FRLM-strengthened arch exhibited higher displacement capacity when compared to arches strengthened with polymeric and cementitious matrix composites.

Lime-Based Mortar Reinforced by Randomly Oriented Short Fibers for the Retrofitting of the Historical Masonry Structure

“…Current standards [30,31] define cement-based mortars to be inadequate for strengthening interventions of historical masonries. Natural Hydraulic Lime (NHL)-based mortars [29,32,33] are considered a promising alternative to cement materials when high chemical-physical compatibility with historical substrates is strictly required.…”

Wall-to-horizontal diaphragm connections in historical buildings: A state-of-the-art review

“…Furthermore, the prestressed force must be conceived, designed and executed carefully: despite the masonry shear force increases with the compression level, the pre-tension induces alterations in the equilibrium of the structure and modifies the tension state of the masonry [34]. Recent suggestions for tying the masonry walls include the possibility to replace the steel ties with reinforced polymer laminates (Figure 8 anchor system [7] capacity, confining the building with vertically and horizontally placed strips [43,45,46,47]. For the latter solutions, precautions must be undertaken to face the great difference in strength and deformability between traditional masonry and innovative polymer, adopting compatible technologies for the bond and the anchoring system.…”

Effects of the Mortar Matrix on the Flexural Capacity of Masonry Cross Sections Strengthened with FRCM Materials

“…Such structures were built according to inadequate codes without seismic criteria. The need to retrofit these buildings today is clearer than before [4][5][6]. In the last few years, new techniques based on the use of fiber reinforced composite materials-i.e., fiber reinforced plastics (FRP) and fiber reinforced cementitious matrix (FRCM)-were developed and studied.…”