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The use of steel fiber reinforced concrete (SFRC) in structures with high physical-mechanical characteristics allows engineers to reduce the weight and costs of the structures, to simplify the technology of their production, to reduce or completely eliminate the manual labor needed for reinforcement, at the same time increasing reliability and durability. Commonly accepted technology is exploiting randomly distributed in the concrete volume fibers with random each fiber orientation. In structural members subjected to bending, major loads are bearing fibers located close to outer member surfaces. The majority of fibers are slightly loaded. The aim of the present research is to create an SFRC construction with non-homogeneously distributed fibers. We prepared layered SFRC prismatic specimens. Each layer had different amount of short fibers. Specimens were tested by four point bending till the rupture. Material fracture process was modelled based on the single fiber pull-out test results. Modelling results were compared with the experimental curves for beams. Predictions generated by the model were validated by 4PBT of 100 × 100 × 400 mm prisms. Investigation had shown higher load-bearing capacity of layered concrete plates comparing with plate having homogeneously distributed the same amount of fibers. This mechanism is strongly dependent on fiber concentration. A high amount of fibers is leading to new failure mechanisms—pull-out of FRC blocks and decrease of load-bearing capacity. Fracture surface analysis was realized for broken prisms with the goal to analyze fracture process and to improve accuracy of the elaborated model. The general conclusion with regard to modelling results is that the agreement with experimental data is good, numeric modelling results successfully align with the experimental data. Modelling has indicated the existence of additional failure processes besides simple fiber pull-out, which could be expected when fiber concentration exceeds the critical value.

Traditional fiberconcrete structures have fibres in the mix oriented in all spatial directions, distributed in the struc­tural element volume homogenously, what not easy to obtain in practice. In many situations, structurally more effective is the insertion of fibres into the concrete structural element body by forming layers, with a predetermined fibre concentration and orientation in every layer. In the present investigation, layered fibre concrete is under investigation. Short steel fibres were at­tached to flexible warps with the necessary fibres concentration and orientation. Warps were placed into the prismatic mould separating them by concrete layers without fibres. Prisms were matured and tested under four-point bending. The bending-affected mechanical behaviour of cracked fibre concrete was simulated numerically by using a developed struc­tural model. Comparing the simulation results with experimental data, material micromechanical fracture mechanisms were analysed and evaluated.

In this research fiber reinforced concrete prisms with layers of non-homogeneous distribution of fibers inside them were elaborated. Fiber reinforced concrete is important material for load bearing structural elements. Traditionally fibers are homogeneously dispersed in a concrete. At the same time in many situations fiber reinforced concrete with homogeneously dispersed fibers is not optimal (majority of added fibers are not participating in load bearing process). It is possible to create constructions with non-homogeneous distribution of fibers in them in different ways. Present research is devoted to one of them. In the present research three different types of layered prisms with the same amount of fibers in them were experimentally produced (of this research prisms of non-homogeneous fiber reinforced concrete with dimensions 100×100×400 mm were designed. and prisms with homogeneously dispersed fibers were produced for reference as well). Prisms were tested under four point bending conditions till crack opening in each prism reached 6 mm. During the testing vertical deflection at the center of a prism and crack opening were fixed by the linear displacements transducers in real time.

Operative determination of consistence of self-compacting concrete mixes at plant or in construction conditions is an important problem in building practice. The Abram's cone, the Vebe's device, the U-box siphon, L-box or funnel tests are used in solving this problem. However, these field methods are targeted at determination of some indirect parameters of such very complicated paste-like material like concrete mix. They are not physical characteristics suitable for the rheological calculations of the coherence between the stress and strains, flow characteristics and the reaction of the concrete mix in different technological processes. A conical plastometer having higher precision and less sensitive to the inaccuracy of the tests in construction condition has been elaborated at the Concrete Mechanics Laboratory of RTU. In addition, a new method was elaborated for the calculation of plasticity limit τ0 taking into account the buoyancy force of the liquid or non-liquid concrete mix. In the present investigation rheological test of the concrete mix by use the plastometer and the method mentioned earlier was conducted for different self-compacting and not self-compacting concrete mixes.

As it has been found out, fiberconcrete has many positive attributes, which make that material a target of the numerous investigations. Traditionally fibers are homogeneously dispersed in the concrete volume. At the same time, in many situations fiber reinforced concrete with homogeneously dispersed fibers is not optimal (the majority of added fibers do not participate in the load bearing process). In the present investigation it has been demonstrated that the use of homogeneous fiberconcrete in eccentrically loaded and subjected to bending structures is not rational from mechanical and economical point of view. Fiber reinforced concrete prisms with homogeneous and layered fiber distribution inside them were elaborated. Prisms were tested under four point bending till macro-crack opening of 4mm and more was reached. Load bearing capacities at different load bearing stages of differently made prisms were compared.

Reinforcing cement-based composites with continuous fibers is one of the most efficient ways to obtain high performance materials. This paper studies the application of layers of knitted textiles with relatively simple fabric architecture used to strengthen fiberconcrete beams. The objective of this study was to evaluate glass knitted fabric as reinforcement for fiberconcrete. For this purpose fiberconcrete beams with textile reinforcement in the form of three plies of glass weft knitted fabric (jersey) were produced. Four point bending test was used to experimentally investigate the influence of textile plies on composite flexural strength. The obtained results were compared with the material without textile reinforcement. The fiberconcrete reinforced by textile layers showed better flexural performance compared to non-reinforced fiberconcrete samples.