Experimental Analysis of Repaired Masonry Elements with Flax-FRCM and PBO-FRCM Composites Subjected to Axial Bending Loads

Abstract

Abstract:In the construction industry, the use of natural fabrics as a reinforcement for cement-based composites has shown great potential. The use of these sustainable composites to provide strengthening or repair old masonry structures that exhibit structural problems mainly due to a poor tensile strength of the mortar/brick joints is revealed to be a promising area of research. One of the most significant load conditions affecting the mechanical response of masonry structures occurs when axial bending loads are applied on the resistant cross-section. In this study, three different types of masonry elements were built using clay bricks and a lime-based mortar. After 28 days, the samples were subjected to concentric and eccentric compressive loads. In order to produce significant bending effects, the compressive loads were applied with large eccentricity, and a sudden failure characterized the behavior of the unreinforced masonry (URM) elements. The tested masonry specimens were repaired using fabric-reinforced cementitious matrix (FRCM) composites produced using bi-directional flax and polyparaphenylene benzobisoxazole (PBO) fabrics. The mechanical behavior of the URM and repaired samples was compared in terms of load-displacement and moment-curvature responses. Furthermore, the results achieved using flax-FRCM composites were compared with those of using PBO-FRCM composites. OPEN ACCESSFibers 2015, 3 492

The use of natural fibers in repairing and strengthening of cultural heritage buildings

“…In a comparative study between PBO and flax lime-based TRM, Olivito et al [54] observed through double-lap test that bond stress [50] values of flax composites are similar to the ones of PBO, which indicated that PBO fibers exploited less than 30% of their mechanical capacity unlike flax fibers. Moreover, the progressive cracking detected with flax-TRM demonstrated better ductile behavior than PBO that had a sudden delamination, see Figure 10, which is concordant with what other studies reported [43] [44].…”

“…That conclusion was reliant on the higher strength attained (more than 25% over PBO-strengthened walls), higher ultimate strains and absence of debonding if compared to PBO-TRM. Another concordant results, considering the study of [44], assured that the capacity of flax-FRCM to transfer the loading to the substrate to release the stored energy, is a preferential aspect that highlights their compatibility to repair damaged masonry. Additionally, the higher bending moment under eccentric loading, good deformability and the ability to restore stiffness might extend the possibility of applying this repairing system to different kinds of loads [43] [44].…”

Simplified Design of Masonry Ring-Beams Reinforced by Flax Fibers for Existing Buildings Retrofitting

“…Such beams allow overcoming many of the now well-known problems that were recognized to be due to r/c beams. This strengthening system was recently studied in some researches by other Authors [42][43][44][45][46], while the validation of this reinforcement solution for masonry beams was verified by experimental tests on full-scale beams reinforced by glass fiber-reinforced polymer composite [28]. Several specimens were tested under cyclic flexure and long duration loading.…”

“…The assumption regarding the bond between bricks and fiber reinforced cementitious matrix composite materials is a well-established hypothesis for this reinforcing technique, and is also based on excellent results achieved in experimental researches. In Codispoti et al [34], Cevallos et al [46] and Olivito et al [54] it is shown that flax fiber reinforced cementitious matrix have a good bond behavior with the masonry support; it is also shown how flax fibers made full use of their mechanical properties in the composite during the tests performed.…”

Análisis del comportamiento frente acciones cíclicas de muros de mampostería reforzados con materiales compuestos de matriz inorgánica y tejidos de fibras vegetales

“…Figura 2.7. Colocación del FRCM [11] Las dos principales aportaciones que realiza la matriz al material compuesto son la conexión entre el material substrato a reforzar (mampostería) y la malla, y la protección de la fibra frente a las condiciones externas (humedad, luz solar, etc.). La primera aportación es la más relevante a nivel estructural puesto que el FRCM únicamente contribuirá a soportar las cargas que la matriz sea capaz de transferir desde la superficie de la mampostería a reforzar hasta las fibras.…”