The development of light and very thin concrete building structures and demand for extremely thin elements in design are inter alia reasons for the development of composite materials as non-traditional reinforcement. Composite materials are currently used as reinforcement mostly in the form of fiber reinforced polymer bars similar to traditional steel reinforcement bars, but the last decade sees also rise in the use of technical textiles. This article is focused on the interaction between impregnated textile reinforcement and high-performance concrete matrix and its easy determination using originally modified pullout test. The second aim of this article is improvement of interaction conditions between reinforcement and cementitious matrix using fine-grained silica sand applied on the surface of the composite reinforcement similarly to the traditional fiber reinforced polymer reinforcement with commonly used diameters. To investigate an effect of this modification a bending test was performed on small thin concrete slabs with different amounts of reinforcement.

The topic of the article is the verification of the tensile mechanical characteristics of selected natural fibres commonly available on the Czech market. Due to their high tensile strengths, some natural materials have a certain potential for use in specific engineering applications such as concrete reinforcement. Additionally, natural fibres are renewable materials, making them an environmentally friendly material. Potentially, its use as a reinforcement in the form of technical textiles for textilereinforced concrete could help create more sustainable reinforced concrete elements. This article deals with tensile tests of chosen available natural fibre materials, such as flax, hemp, jute, and sisal, both pure and impregnated (homogenised) using epoxy resin. In this article, the results and comparisons of tensile strengths and Young’s modulus are presented.

Textile-reinforced concrete is becoming more and more popular. The material enables the realization of very thin structures and shells, often with organic shapes. However, a problem with this reinforcement occurs when the structure is bent (contains a corner), and the flexural stiffness around this bent area is required. This article presents the design, solution, and load-bearing capacity of an L-shaped rigid frame made of textile-reinforced concrete. Basic material parameters of concrete matrix and carbon textile reinforcement were supplemented by a four-point bending test to calibrate fracture energy Gf, critical compressive displacement Wd, solver type, and other parameters of a numerical model created by Atena Engineering in specialized non-linear structural analysis software for reinforced concrete structures. The calibrated numerical model was used to evaluate different variants of carbon textile reinforcement of the L-shaped frame. The carbon textile reinforcement was homogenized using epoxy resin to ensure the interaction of all fibers, and its surface was modified with fine-grained silica sand to increase the cohesion with the concrete matrix. Specimens were produced based on the most effective variant of the L-shaped frame reinforcement to be experimentally tested. Thanks to the original shaping and anchoring of the reinforcement in the corner area, the frame with composite textile reinforcement is rigid and can transmit the bending stresses in both positive and negative directions. The results of the mechanical loading test on small experimental specimens correspond well to the results of numerical modeling using Atena Engineering software.

This article presents woven carbon-fiber-reinforced polymer (CFRP) tubular mesh used as a reinforcement on the inner surface of hollow beams made of high-performance concrete (HPC). The tubular mesh was designed to serve as both the tensile and shear reinforcement of hollow beams intended for the construction of small self-supporting structures that could be assembled without mechanization. The reinforcement was prepared with a tri-axial weaving machine from carbon filament yarn and was homogenized using epoxy resin. The interaction of the composite reinforcement with the cementitious matrix was investigated, and the surface of the reinforcement was modified using silica sand and polyvinyl alcohol (PVA) fibers to improve cohesion. The sand coating enhanced bond strength, resulting in the significantly higher flexural strength of the hollow beam of 128%. The PVA fibers had a lower positive effect of 64% on the flexural strength but improved the ductility of the beam. Individual beams were connected by gluing steel parts directly inside the hollow core of the HPC beam. This procedure provides good interaction between the CFRP reinforcement and the glued steel insert and allows for the fast and simple assembly of structures. The weaving of additional layers of the CFRP reinforcement around HPC beams was also explored. A small structure made of the hollow HPC beams with inner composite reinforcement was constructed to demonstrate the possibilities of the presented technology.

Structures made of textile-reinforced concrete can reach minimal thickness which results in attractiveness and saving primary resources. This paper presents the application of textile-reinforced concrete on cantilever staircases. The goal was to design a subtle and architecturally interesting staircase which would be easily build from prefabricated parts. The advantage of textile-reinforced concrete is the combination of non-corrosive reinforcement and fine-grained concrete which results in minimal dimensions which would not be possible with normal concrete and steel reinforcement. This work is focused on the design of cantilever staircase. Its load bearing capacity was also experimentally determined with the focus on the interaction between the prefabricated parts.

Bio-based materials are gaining attention across various industrial sectors as sustainable alternative to conventional materials, with a significant emphasis on concrete – the most widely used construction material. The incorporation of natural fibres provides technical, environmental, and economic advantages. Derived from renewable resources, these fibres reduce carbon footprint, and provide non-toxicity, biodegradability, corrosion resistance, and wide availability. However, they typically possess lower strength, and reduced durability compared to synthetic fibres. Presented study aims to compare not only the mechanical properties of selected natural and synthetic fibres but also their environmental impact. Natural fibres flax, hemp, jute, and sisal in the form of yarn, and synthetic rovings alkali-resistant glass, basalt and carbon were fabricated into continuous fibre composite reinforcement (CFCR). Their tensile strength was evaluated, and they were utilized as reinforcement of thin high-performance concrete (HPC) plates tested in a four-point bending test. The flax and hemp yarn CFCRs showed as viable reinforcement of HPC structures, while carbon-hemp hybrid showed great potential due to its good mechanical performance and less brittle behaviour. The following LCA analysis was performed in compliance with EN 15804:2012 + A2:2019/AC:2021. The results showed that natural fibres significantly reduced the carbon footprint of the concrete samples. However, the incorporation of natural fibres in concrete slabs increased the environmental impact across several categories, particularly acidification, and eutrophication, primarily due to the use of pesticides, herbicides, and fertilizers.