Compatible Composite Materials for Strengthening Masonry Columns

Fiber reinforced composite systems are successfully used in the case of masonry structural elements belonging to architectural heritage because of the compatibility with the masonry substrate as well as the reversibility of the intervention. In this paper, the influence of compatible matrices in the effectiveness of masonry column confinement is investigated experimentally and analytically. Three different matrices are considered: a natural lime mortar, a cement mortar and a commercial mortar. TRM (Textile-Reinforced Matrix) system was obtained by embedding a PBO (polyparaphenylene benzobisoxazole) fabric within these matrices. Results of axial compression tests demonstrate the effectiveness of confinement in all cases, highlighting the different increases in the load-bearing capacity and ductility of the columns provided using different matrices. The main predictive formulas available in the literature were used to compute the increase in the load-bearing capacity of the tested columns, providing values very different than those obtained experimentally. The authors believe that these formulas, which are affected by coefficients fine-tuned by the various authors based on their experimental results, need to be further calibrated. Accordingly, the use of two different equations in the case of TRM-matrices having compression strength higher or lower than the strength of the unconfined column is proposed.