Compressive strength of concrete confined with fabric reinforced cementitious matrix (FRCM): Analytical models

Composite materials employing cement-based mortars, usually known as fabric-reinforced cementitious matrix (FRCM) composites, have recently emerged as an attractive solution for the repairing and strengthening of reinforced concrete or masonry members. They represent a promising alternative to the use of Fiber Reinforced Polymer (FRP) composites when there is a need to overcome some of the drawbacks related to the epoxy resin, such as moderate matrix heat and fire resistance, difficulty of application at low temperatures, impossibility of application on wet surfaces, and lack of vapor permeability. This paper presents an analytical study on the confinement of concrete columns with FRCM composites with the twofold objective to: (a) propose new models for the estimate of the compressive strength, and (b) assess existing models available in the literature and in some international guidelines. To this purpose, a wide database including results of compression tests performed on over 290 concrete cylinders externally wrapped with FRCM was assembled from the literature. The collected results were employed to perform an overall analysis of the efficiency of the FRCM confinement by varying some of the relevant parameters, such as: type of fiber (glass, carbon, steel, PBO or basalt) and geometry of the mesh, number of employed layers, mechanical properties of the inorganic matrix and compressive strength of the unconfined concrete. Relationships for estimating the compression strength of the FRCM confined concrete were then developed through best-fit analyses, and comparisons with some formulations available in the literature and in some international guidelines were performed.