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.

Piezoelectric harvesters are environmentally sustainable alternative electrical production technologies aimed at supplying small autonomous devices. The particular application in roads has significant potential. However, there are discrepancies about the effectiveness of these harvesters, and their costs limit their market expansion abilities. In this context, a novel harvester approach is explored that includes low-cost membrane piezoelectric patches in modified cymbal devices. The main novelty of this approach is the inclusion of an inner contact column that punctually transmits the load of the caps of the cymbal to the centre of the membrane piezoelectric patch, maximising its deformation and energy production capabilities. Experimental tests on piezoelectric elements, harvesters and embedder harvesting units have been performed with numerical simulations to optimise the design of the harvester. The results indicate that the more punctual the inner contact column is, the more electrical energy is produced, reaching values ten times greater than those of the present cymbal configuration. Embedding the harvester into a flexible pavement and positioning it under a wheel track are beneficial aspects of the execution. Finally, the dependency on the wheel speed is confirmed with wheel-track tests on a representative pad of the system.

Fabric-reinforced cementitious matrix (FRCM) composites are materials that are usually applied to strengthen existing structures. In this study, a hemp mesh coated with epoxy was manufactured and combined with a cementitious matrix to strengthen a concrete beam. This beam was subjected to bending cyclic loading tests and a nondestructive modal analysis test. The modal analysis was performed to determine the dynamic elastic properties of the beam under pre-cracking, post-cracking, and strengthened conditions. The beam stiffness increased following strengthening with hemp-FRCM. The results of the experimental cyclic loading test showed that the hemp-FRCM system improved the load-bearing capacity of the beam at the service limit state by 42%. Analytical and numerical models were adjusted and validated using the experimental results, and both proved to be effective calculation tools. The models accurately reproduced the behaviour of the FRCM-strengthened concrete beam if the strengthening connection could prevent sliding and mortar debonding failures.

This study investigated the utilization of innovative green composites made from hemp shiv, a waste by-product of hemp cultivation, with the aim of promoting sustainability within the construction industry. The manufacturing method involved the application of pressure in a mold to create the samples. These materials were produced using an environmentally friendly binder consisting of colophony, arabic gum, and corn starch. Moreover, white glue and bioepoxy were also used to compare with the green resins. Three different binder compositions were used for the specimens. The samples underwent mechanical testing through tensile and bending assessments, and their performance was compared to that of non-green binders to validate the effectiveness of the manufacturing processes. The study revealed that decreasing the moisture content during the curing process was crucial for improving the mechanical properties. The best results were achieved when using arabic gum as a binder, yielding a tensile strength of 2.16 MPa and a bending strength of 5.25 MPa, with a composition of 62.5% hemp shiv and a manufacturing process involving a pressure of 5 MPa.

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.