Effect of corner over-reinforcing strips on the compressive behaviour of TRM confined masonry columns

Several recent works studied the efficiency of inorganic matrix composites, namely Textile Reinforced Mortar (TRM) or Fabric Reinforced Cementitious Matrix, for enhancing the strength and shortening capacity of masonry columns subjected to axial load. Literature studies were addressed to study the great number of variables involved in the problem, such as the nature and the grade of mortar, the strength of the fabric, the number of reinforcing layers, the type, the arrangement and the strength of the masonry, and helped to draw the first technical guidelines for practitioners and designers. All the experimental works highlighted that the actual performance of TRM confinement in masonry members was limited by the premature failure of the external layer in correspondence of the corners of sharp-edged sections, due to the stress concentration, limiting the confinement pressure achievable from the external wrap. This paper presents the result of an experimental investigation which aims to study the effect of a corner strengthening detail on the compressive behaviour of calcarenite masonry columns wrapped with glass TRM. The study was performed by varying the number of textile layers and the grade of the mortar adopted for the composite. The results show that the introduction of a fabric strip in correspondence of the corners can limit the stress concentration at the edges, allowing to exploit the confinement pressure of the TRM and achieving greater strength increases.