Search

Featured Application: The design and manufacturing of sandwich solutions using FRCM vegetal fabric skins improve sustainability because they provide solutions with a lower global carbon footprint. The utilization of the vegetal fabric-reinforced cementitious matrix (FRCM) represents an innovative approach to composite materials, offering distinct sustainable advantages when compared to traditional steel-reinforced concrete and conventional FRCM composites employing synthetic fibers. This article introduces a design for sandwich solutions based on a core of extruded polystyrene and composite skins combining mortar as a matrix and diverse vegetal fabrics as fabrics such as hemp and sisal. The structural behavior of the resulting sandwich panel is predominantly driven by the interaction between materials (mortar and polyurethane) and the influence of shear connectors penetrating the insulation layer. This study encompasses an experimental campaign involving double-shear tests, accompanied by heuristic bond-slip models for the potential design of sandwich solutions. The analysis extends to the examination of various connector types, including hemp, sisal, and steel, and their impact on the shear performance of the sandwich specimens. The results obtained emphasize the competitiveness of vegetal fabrics in achieving an effective composite strength comparable to other synthetic fabrics like glass fiber. Nevertheless, this study reveals that the stiffness of steel connectors outperforms vegetal connectors, contributing to an enhanced improvement in both stiffness and shear strength of the sandwich solutions. [ABSTRACT FROM AUTHOR]

Fiber Reinforced Cementitious Matrices (FRCM) is an interesting solution to retrofit structures, due its compatibility with the substrate and its versatility. This paper presents the application of vegetal-FRCM for strengthening RC beams. Two types of vegetal fibers, cotton and hemp, were coated with epoxy and polyester resin and were embedded into a mortar matrix to retrofit RC-beams subjected to cyclic bending loads. Additionally, FEA simulation analyses of the cyclic bending tests were conducted. Modal analysis was performed on both pre- and post-strengthened RC beams to assess the impact of FRCM on their vibrational modes. The application of FRCM increased the frequency of the 1st bending vibrational mode, enhanced the maximum load-bearing capacity of the specimens between a 4 and a 22 %, and delayed the appearance of cracking in the substrate. The numerical simulation proved to be reliable until the yield point, therefore it is suitable for determining design parameters. • The FRCM-strengthening increases the maximum load between a 4 and a 23 %. • The application of the FRCM increases the modal frequencies of the RC beam. • The application of the FRCM delays the cracking of the RC beam. • Cotton-FRCM is able to dissipate enough energy to maintain the steel armor without breaking. [ABSTRACT FROM AUTHOR]

Featured Application: The reinforcement of concrete structures using FRCM is a rather novelty approach that overcomes some of the drawbacks of organic composites such as carbon fiber CFRP. Moreover, the use of vegetal fabrics has a direct effect on the carbon footprint. Some calculations deal with a full composite action between the matrix and the fibers. Nevertheless, it has been noticed that sometimes the chemical and mechanical adherence between the cementitious matrix and the vegetal fabric does not perform as a perfect bond, and it is necessary to take into account that the matrix–fiber bond is weak. This research provides insight into the limits of the strength for these situations. Partial interaction allows the composite to strengthen with larger deformation while maintaining an interesting ultimate capacity. The characterization of this type of performance may help to design resilient solutions for concrete structures under critical bonding situations produced by ambient or manufacturing reasons. FRCM is a strengthening system based on composite material made of a cementitious matrix and fabrics. This strengthening system has been studied and researched, obtaining analytical predictive models where it is common to assume full composite action between components. Through using non-typical materials for these composites, it has been seen that, in some cases, the previous assumption cannot be taken. In this situation, traditional analytical models such as ACK or tri-linear ones do not offer a reasonable prediction. This work researches the behavior of synthetic and naturally coated vegetal-FRCM with partial interaction through the characterization of the materials through tensile tests. Yarns, meshes and different FRCM coupons were manufactured and mechanically tested using different types of coatings and fabrics. The use of colophony and Arabic gum as natural coatings provided similar mechanical properties to the cotton and hemp yarns and meshes conformed. Partial interaction was found when using epoxy as a natural resin to coat the reinforcement while maintaining the mechanical properties in the same order of magnitude. A new two-stage model is proposed to fit stress–strain mechanical test, and it is reliable and accurate for cotton specimens. [ABSTRACT FROM AUTHOR]