Failure Modes of Masonry Pillars Strengthened with PBO Fibres

Abstract

The paper presents compression tests of stocky and slender masonry pillars strengthened in bed joints with PBO fibres and an inorganic matrix. Five stocky pillars and four slender pillars were tested under static loading. Physical models were prepared using lime mortar similar to that used in historical structures. Fibres were applied in the grooves that were made after the mortar setting period in order to recreate real-world conditions. One of the models was subjected to preloading before the strengthening was applied. The failure modes, load-bearing capacity, cracking stresses, stiffness and deformations (longitudinal and transverse) were all determined through experimental testing. Strengthening effectiveness in terms of the increase in load-bearing capacity and stiffness, as well as anti-cracking was determined on the basis of the experimental results. The results obtained for the stocky and slender pillars were also compared, indicating the influence of slenderness on strengthening effectiveness. Special attention was also paid to failure modes and the interaction of the PBO fibres with the bed joint. Methods that strengthen pillars in their bed joints using PBO fibres increase their load-bearing capacity, stiffness and cracking resistance, while maintaining a satisfactory visual appearance which is especially important in heritage structures.