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FIBRE CONCRETE 2019

10^th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance cementitious composites (UHPC)

The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance cementitious composites regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering.

The 10^th International Conference Fibre Concrete 2019 provides opportunity for presenting of 50 papers for participants from 14 countries all over the world. The keynote lectures are given by Professor Bažant and Professor Akira Hosoda.

The conference program covers wide range of topics from scientific research to practical applications. The presented contributions relate to performance and behaviour of cementitious composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications.

This conference was organized also to honour Professor Vladimír Křístek on the occasion of his jubilee and to appreciate his merits and discoveries in the field of concrete and cement based composites, structural mechanics and engineering.

List of Scientific committee, Editorial committee and Organizing committee are present in this pdf.

List of Conference Partners are available in this pdf.

List of List of Participants are Available in this pdf.

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The microplane constitutive model M7f for fiber reinforced concrete (FRC), previously calibrated by extensive material test data, is used in computational simulations of the size effect in geometrically similar notched specimens, and in simulations of penetration of projectiles into FRC targets. The M7f microplane model for fiber reinforced concrete is calibrated at the material level and then used to predict structural level behavior. The results show that, for any fiber volume ratio, the Type 2 size effect must be expected.

The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. The objective of the presented investigations was to verify the proposed breakthrough approach to utilisation of crushed waste concrete in construction of various types of structures. The traditional philosophy of the designing procedure – to find a suitable material for a given structure – is transformed into a new way of designing entitled "inverse design approach" that intends to find a suitable structure for a low-strength porous composite material that is obtained from available recycled rubble concrete. In the first stage, composition of concrete mix optimal from the point of view of mechanical properties, workability and economy is estimated based on the experience of the authors. The keynote is maximising of recycled aggregate use, minimising of cement consumption and providing competitive advantage of the composite made from concrete waste. Properties of the material are determined in laboratory tests. Possible applications of the composite in the construction industry are proposed. Finally, one of the possibilities is selected for verification. The results have shown that the introduced inverse design approach is applicable; it can lead to exploitation of significant amounts of construction waste in a useful way, to substantial savings of primary resources and to reduction of carbon footprint of the construction process.

Quantity of the fibres intersecting the unit cross section is a relevant parameter. Firstly, the residual tension strength, which is the base of the material model of the fibre reinforced concrete, depends most on the number of fibres intersecting the cracked cross section. Secondly, by counting the fibres on the cross section of the broken test specimen the non-uniform distribution of the fibres can be examined and taken into account during the evaluation. Therefore, for most of the material model the initial parameter is the quantity of fibres intersecting the unit cross section.

In the present work the predictive performance of the two approaches proposed by Model Code 2010 for the evaluation of the shear capacity of fiber reinforced concrete (FRC) elements flexurally reinforced with conventional steel bars is assessed considering a database (DBs) constituted by 80 FRC beams do not including conventional transverse reinforcements. The accuracy of these shear models is evaluated by statistical analysis of the prediction ratio between the experimental and estimated shear capacity of the beams of the DBs, and applying the Demerit Points Classification approach for further information about the reliability of the two approaches in design context. Due to the absence of the post-cracking experimental characterization of the FRC used in several beams considered in the DBs, an approach was developed for estimating the residual flexural strength parameters from the most relevant known variables of steel fiber reinforcement mechanisms for concrete, namely the fiber volume and aspect ratio, and the concrete compressive and tensile strength. The residual flexural strength prediction model is assessed and its influence on the performance of the shear resistance models is evaluated.

The modeling of steel fiber reinforced concrete (SFRC) is a challenging task in comparison with the conventional reinforced concrete structures. Softening functions used to numerically reproduce SFRC fracture need to describe the effects associated with the post-cracking residual strength induced by the fibers in the concrete matrix. In order to do this, multilinear softening functions can be used to consider these effects. The work presents the results of a study in which the behavior of a SFRC beam tested in four-point bending test is compared with the responses obtained in nonlinear simulations using the finite element method. Multilinear softening functions are obtained through an inverse analysis technique, aiming to reproduce the phenomena of appearance and propagation of cracks. The simulations were performed using ATENA/GiD software. The technique adopted to find the softening function of SFRC allowed to reproduce, with a good agreement, the behavior reported experimentally.

In previous research a simplified closed-form non-linear hinge model based on the Third Point Bending Test (TPBT) developed by the authors to derive the tensile material properties of Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC) was numerically validated. This simplified non-linear hinge model was calibrated for UHPFRC that exhibits strain-hardening constitutive behavior. The aim of this work is the numerical validation of the simplified inverse analysis method to characterize the tensile properties of UHPFRC even with those UHPFRCs which exhibit strain-softening behavior. To get this objective a Finite Element Model (FEM) is carried out. The parameters to characterize the concrete properties from the simplified inverse analysis method by means of TPBT are used in the numerical modelling. The constitutive model for UHPFRC is modelled using a discrete crack approach for the macrocrack position. Different parameters are analysed to quantify the accuracy of the FEM. As a result, the model shows conservative load-deflection response when it is compared to the experimental curves.

The study of fibre-reinforced concrete (FRC) has become of increasing interest in the last decades. Although it is not a new technology, it has experienced a remarkable progress with the appearance of some recommendations in the standards. More specifically, the use of polyolefin fibres has proved to increase the tensile strength of concrete without the problems usually found with steel fibres, especially those related to corrosion. This type of fibres have been studied in depth and its fracture behaviour has been successfully simulated in the past by means of an embedded crack model using a trilinear softening function. Nevertheless, these simulations have been always focused on cases where fracture took place under pure mode I conditions, namely using the classical three-point bending test on notched specimens. In this study, such embedded crack model is used to reproduce the fracture behaviour on notched specimens subjected to a modified three-point bending test that induces fracture under a combination of modes I and II. Three PFRC mixes are analysed, all of them with the same proportions of concrete components but different proportions of polyolefin fibres. The experimental and numerical diagrams properly agree and allow identifying how the increasing proportion of fibres can be reflected in the trilinear softening function that numerically drives the damage evolution.

Methods and software tools for material parameter identification of high-performance cementitious composites are presented. The aim is to provide techniques for the purpose of advanced assessment of their fracture–mechanical properties and subsequent numerical simulations of components/structures made of these materials. The paper describes development of computational and material models utilized for efficient material parameter determination of studied composite. Such a determination is performed with the help of experimental data from four-point bending test used in inverse analysis based on artificial neural networks. It is a part of complex methodology for statistical and reliability analyses of fibre reinforced concrete structures.

Steel fibre reinforced concrete (SFRC) is more and more used as construction material. Well-known are applications for industrial floors. Nevertheless, this material is also widely used in structural concrete elements where it is especially effective to cover crack widths in combination with standard conventional reinforcement. Currently there is no general part in Eurocode 2 [1] for buildings regarding steel fibre concrete. There are various standards and recommendations for the calculation of the steel fibre contribution. One of the most applied publications is the German guideline DAfStb [2] which was used as a basis for the numerical analysis outlined in this paper. Thus, company SCIA N.V. together with Bekaert N.V. as producer of DRAMIX^® fibres developed a special tool for designing and checking SFRC structures. This tool was built in into finite element software SCIA Engineer and based on the German guideline. To gain a fundamental understanding of the structural behaviour, we have also developed non-linear FEM models, which contain a built-in module for SFRC structures. Numerical simulation results are compared to experimental performance of SFRC slab on piles of the Nanhui project in Shanghai in terms of ultimate load and crack pattern.

Steel fibre reinforced concrete has developed over years for the use in structural applications. The material itself has undergone development into higher performing steel fibre types and thus into higher performing steel fibre concretes. Whilst in regards to standards the development went from recommendations into building codes the way of designing – linear elastic design methods or yield line theory – and the way of quality control seemed to remain unchanged from the past. This paper shall emphasize the recent development in a design tool that enables a non-linear design methodology and a new advanced way of real time quality control.

This paper deals with new UHPFRC (Ultra High Performance Fibre Reinforced Concrete) bridges produced or constructed in 2018 in the Czech Republic. The paper includes a short description of 3 unique pedestrian bridges with load bearing structure made of UHPFRC and 2 steel bridges over the railway track with lost formwork for bridge decks and cornices made of thin UHPFRC slabs. Focus is given on the testing of the material, comparison of test specimens and summary of results from UHPFRC production in real scale. The size effect of control specimen and the results analysis is given in the last chapter. The 3 mentioned unique pedestrian bridges are Footbridge over the Lubina river in city Příbor, Pedestrian and cycle bridge in the vicinity of Black Bridges in city Tábor and Footbridge over Dřetovice stream in Vrapice - a district of Kladno city. Thin panels as permanent lost formwork for two bridges over the railway tracks are in city Přerov. All new UHPFRC structures should be worthy of attention of bridge experts and community of specialists in the field of concrete engineering.

The paper presents a summary of the development of bridge precast beams in EUROVIA CS company in the last years. Several types of beams are described. The first beam that has already been applied in real construction is an Omega beam which consists of shell outside envelope enabling construction of a bridge without intermediate supports in midspan. The second one is an inverted T beam for railway and road bridges. At present, the development of UHPC beams for footbridges is going on. The plan is to create a set of shapes and solutions usable for various configurations with spans up to 15 m, fully exploiting the UHPC advantages. Another element for bridge construction developed by Eurovia and its partners is the lost formwork panel used for bridge superstructures built from both concrete and steel beams.

The disposal container with low and intermediate level radioactive waste (LILW) was developed using self-consolidating concrete (SCC), which provides long term mechanical properties and extremely low permeability for liquids. In the paper, some results of additional investigations are presented, which complement the assessment of the behaviour of SCC during use. The main focus is the presentation and discussion of the results of SFR-SCC (steel fibre reinforced - self-consolidating concrete) tests in fresh and harden state. From these results it can be seen that there is a possibility of further improving the properties of the SCC and thus the container.

Steel fibres in construction materials not only enhance their mechanical and fracture properties but also increase their capability of electrical conductivity. This feature thus enables the material to obtain advanced multifunctional properties that can be utilized in self-sensing and other smart applications. Fly ash geopolymers with steel microfibres in 5−30% wt. were prepared to assess the influence of the fibres on selected electrical properties of the composite (resistance, capacitance and relative permittivity) with respect to mechanical performance. Microstructure and interfacial bonding of matrix and steel fibres was observed by electron microscopy imaging. Steel fibres caused an improvement in all assessed electrical properties but only above a certain frequency values. Furthermore, steel reinforced samples exhibited increase in both compressive and flexural strength.

Lightweight renders with improved thermal performance, resistant against moisture and respecting specific behaviour of original plasters and substrates became attractive materials for surface finishing of both historical and old wall structures. In this respect, structural, mechanical and thermal properties of cement-lime based renders containing a different amount of perlite as fine silica sand substitution are researched in the presented paper. Experimental tests conducted for 28 days samples showed significant lightening of hardened renders with increased perlite content in their fresh mix. Gained strength parameters were, because of higher total open porosity of perlite enriched samples, lower compared with reference material. On the other hand, newly developed lightweight renders exhibited improved thermal insulation performance due to the highly porous perlite particles. In summary, cement-lime renders with incorporated lightweight aggregate based on expanded perlite were considered as alternative and promising materials for application in repair and restoration of historical masonry.

Two configurations are currently used to determine the tensile strength of fibre reinforced concrete: simply supported beams of square cross section loaded either by two forces at thirds of spans (four-point bending test) or by one force at the mid-span where the specified cross section is weakened on the tensile side by a notch (three-point bending test). Based on elementary formulas, the tensile strength of fibre reinforced concrete is then determined. Considering the unacceptability of these formulas to capture the 3D problem and, in particular, for the three-point bending test, also because of significant singularities at the notch and the degree of statistical uncertainty in determining the actual position of the weakest area of the test specimen, such a test does not respect the real stress distribution in the tensile area which is changing in the process of load increase. The proposed adjustment of the test specimen eliminates these fundamental drawbacks by removing the singular areas of the specimen and leaving only the cross-sectional areas where only uniaxial stress state may be assumed. The results obtained by this methodology are presented, statistically evaluated and compared with the currently used procedures.

This paper presents results of extensive experimental programme which took place in 2019. Two proprietary ultra-high performance fibre reinforced composite materials were tested for their blast (contact and close-in) resistance. In total, twenty-eight specimens were tested. Specimens were loaded with explosive charge of weight of 100 - 1000 g in various distances. All specimens were visually evaluated for the damage extend, failure mode and crack pattern. Results from the experiment were compared to the results available in literature for normal strength reinforced concrete. Results showed that both tested premixes performed better than ordinary mixtures in terms of blast resistance. Difference between tested materials and commonly used mixture are described as well. Finally, both materials were compared from the material properties point of view as well as by their blast resistance performance.

The paper describes composition proposals and subsequent optimization and testing of developed fibre-reinforced UHPC mixtures, which seem to be optimal as construction material for the blast and ballistic protective systems, such as mobile blast-resistant walls and covers, which are the expected outcomes of the presented research project. Methods of laboratory testing and optimization of developed UHPC mixtures, with the aim of achieving the best possible values of physical-mechanical parameters, are described in this paper. In connection with laboratory verification, field blast tests of UHPC board samples and consequently of the entire blast-resistant wall system were realized and resistance to dynamic stress was investigated.

This paper presents experimental program focused on determination of material properties of various types of fiber reinforced concrete exposed to elevated temperatures up to 1000° C. Material properties were measured by several methods which are described and compared. The resulting changes of material properties depending on temperature are presented. The values are compared with values from literature and standards. The aim of this paper is to provide a comprehensive overview of material properties of these types of concrete depending on elevated temperature and possibility of their measurement.

This paper describes the influence of internal composition of fiber reinforced cement composites on resistance to near field blast. The influence of multiple basalt meshes and dispersed fibers on a damage induced by a near-field blast is studied and numerically evaluated. Experimental measurements performed in the Boletice military area in 2014, 2015 and 2016 are evaluated by numerical simulations. The evaluation of the results is mainly focused on the stress in the cement composite, propagation of the overpressure caused by the blast and velocity of the ejected parts from the specimen. The influence of velocity of ejected parts coming out of the specimen, originally caused by the impact of a steel plate which bears TNT charges, is examined. And last, but not least, the influence of presence and position of basalt meshes in the specimen on its damage induced by delamination is also examined.

In this paper we study the influence of the damping on the stress and displacements response for a reinforced concrete structure P + 4. In this sense, it was used a mesh consisting of two overlapping layers with common junctions. A concrete layer and a reinforcement layer Therefore, a numerical study was carried out by the help of an especially made program (a rewriting of the NONSAP PC program where a graphic postprocessing software was created). Finally, we obtained the structural response from the effect of the concrete degradation in the areas of the plastic joints. The paper presents our recommendations regarding the use of damping for reinforced concrete structures.

Structural control under the serviceability limit state is a requirement of design codes to ensure the durability of structural elements. As it is possible to consider fibers to be reinforcement in concrete, UHPFRC can be used to guarantee properly distributing cracks and limiting crack width in the serviceability limit state. This research presents an experimental testing method for direct tensile tests on UHPFRC specimens. The results obtained from the proposed method, such as the specimen's average tensile stress-strain curve, tensile stress in concrete, number and width of cracks, can be used to consider the behavior and design requirements of UHPFRC under serviceability conditions.

UHPC (Ultra High-Performance Concrete) is an innovative material that enables design of lightweight and structurally optimized, long-lasting structures. In this paper is presented experimental analysis of precast webs of "butterfly web" box-girder bridge on scaled-down specimens. Pretensioned beam specimens were analysed in 2 variants – with continuous web and with lightened web. Based on the experimental results are both variants compared and are presented numerical and material models suitable for UHPC modelling in software SCIA Engineer. In SCIA Engineer is implemented modified Mazarz material damage model which is applicable for material with residual strength typical for FRC and UHPFRC.

The behaviour and failure mode of reinforced concrete elements strengthened with a thin tensile layer of ultra-high performance fiber-reinforced concrete (UHPFRC) is governed by the interface interaction between the UHPFRC and conventional concrete. In order to analyze the relative displacements at the interface and its influence on the crack pattern evolution and monolithic response, digital image correlation (DIC) has been used in this contribution. With the help of DIC, the distinct stages of the behaviour of UHPFRC-strengthened beams have been correlated with the crack formation and development. Special attention has been paid to the progressive debonding due to the strain incompatibility between UHPFRC and conventional concrete when cracks develop. It is shown that the utilization of the capacity of the UHPFRC can be achieved from a certain thickness of the strengthening layer for shear-critical elements, thereby providing a gain of shear strength and ductility. In contrast, a thinner UHPFRC layer has been more beneficial for flexure-critical elements.

Since the composite nature of Fibre Reinforced Concrete materials, their performance is strictly dependent on the mechanical properties of their components, matrix and fibres, but, above all, on their interaction. The collaboration of the two materials is directly responsible of the force transferring mechanism from concrete to fibres that reflects their contribute in the residual flexural strength performance. This paper aims at understanding how the concrete admixture components might affect the bond of polypropylene crimped fibres, and presents the preliminary results of an experimental campaign consisting of pull-out and compression tests. Four water cement ratios and three cement-sand ratios were considered. The experimental analysis is also supported by the calibration of a numerical model that simulates the pull-out behaviour of a single fibre.

The behaviour of masonry elements under in-plane loads can be improved by using strengthening overlays. However, the changes in stiffness of the elements after strengthening may have various effects at the level of the behaviour of the entire structure. Advanced numerical simulations can be a helpful and cost effective strategy to guide the efficient design of strengthening systems. These models should simultaneously show the ability to deal with the complexities associated with the composite behaviour of panels at a smaller scale, and allow the simulation of models that can include the entire structure. A constitutive model for a 3D interface finite element, implemented in a FEM-based computer program, was applied for the simulation of the interfaces between substrate and the Fabric Reinforced Cementitious Matrix (FRCM) overlay. The mechanical behaviour of the interfaces between the different layers of the strengthened masonry elements were obtained from direct shear tests on couplet specimens. Subsequently, these results were used to define the constitutive laws of the interface elements. Finally, the numerical model developed was used to simulate the in-plane structural response of the strengthened masonry specimens.

The recent development in the construction industry has significantly influenced the socio-economic growth and the built environment of the mega cities around the globe. However, these developments have also resulted in millions of tonnes of construction demolition waste, which is mainly dumped, in the already populated landfills. As a result, the construction waste is not only causing a threat to the natural resources but also to the already deteriorating environment. Over recent past, studies have been conducted which investigated the use of concrete based construction waste as recycled coarse aggregates in preparing concrete for structural purposes. Based on these studies, in general it was found that the concrete compressive strength decreases with the increase in the percentage of recycled aggregates. Furthermore, studies have also been carried out in which use of Carbon Fiber Polymers wrapped along the outer surfaces of the structural elements resulted in significant increase of load carrying capacity. Therefore, in this study, investigation aims at the behaviour of reinforced concrete columns made with recycled aggregates and wrapped with Carbon Fiber Reinforced Polymers under uniaxial static compressive loading. For this purpose, 12 rectangular specimens having cross section dimensions of 150mm x 300mm and height of 600mm reinforced both longitudinally and transversely were used. The specimens were made with three different mixes of concrete having 0%, 30% and 50% of recycled aggregates. It was found that the recycled aggregates reinforced concrete specimens wrapped with CFRP exhibited higher compressive loads as compared to their corresponding specimens made with natural aggregates.

The renewed interest in the preservation of non-renewable resources has made the use of plant-based natural fibres as an environmentally friendly replacement to their synthetic counterparts in construction materials a necessity. This is due to the ability of plant-based natural fibres to enhance the mechanical properties of building components, their relatively low cost, and their derivation from a renewable resource. In this paper, the feasibility of using date palm fibres in cement composites as a replacement for synthetic fibres is reported. This study has reported on the production, types, and comparison between the chemical and mechanical properties of date palm fibres and synthetic fibres.

Low capacity of river banks is a problem of many world cities. Extension can be realised in many ways. One of the ways is to use a system of floating piers. Usual types of piers are filled with floating material, which supports the pier for the whole lifetime. The system of piers described in this article is innovative, because it is supported by an air bag, which can be deflated and then the whole system sinks down to the bottom of the river. This can be helpful in case of danger of floods, because there will be no need to transport the piers to a secure dock. Piers are designed for easy modular connection in various groups. The main types of groups are linear and areal. This article briefly describes the design of fibre reinforced concrete pier and other support constructions which are necessary for the right function of the system. The design of the pier was verified by hydraulic experiments on models in scale 1:10 to real pier. The article contains the description and results of the experiments that have proven the system to be feasible.

This paper compares blast resistance of multi-layered and single-layered concrete panels having different thickness and reinforcement and subjected to various explosive charges. The panels were analysed by ultrasound measurements before the application of blast loading; the velocity of transfer of ultrasound waves through the panels was determined. The same measurement was conducted after exposing the panels to contact explosion and the damage was evaluated based on the determined changes. Nine panels were tested, four of them single-layered and five of them multi-layered. The weights of Pentrite explosive charges were 150 g, 300 g and 500 g. The results show that multi-layered panels are suitable for the protection of soft targets or as cladding of load-bearing structures.

The paper describes experiments aimed at setting parameters for an efficient design of new types and shapes of energy dissipators on chutes of dam spillways. During major rainfall events, large water inflows into the reservoir induce a rise in the reservoir level, and a spillway system must be installed to spill safely the flood waters. Two key challenges during the spillway design are conveyance and energy dissipation. Energy dissipation on dam spillways can be achieved by a range of dissipator designs. One type of spillway is a block ramp. Block ramps are hydraulic structures which are often used in practical applications to assure a correct balance between hydraulic functioning and the environmental impact. One of the main peculiarities of this approach is the capacity to dissipate a larger energy amount than other traditional structures. Thus, significant efforts were spent by the scientific community around the world in order to optimize their energy dissipation efficiency. The use of fibre concrete for the design of reinforced block ramps can improve their resistance significantly. The presented experiments describe the boundary condition for the design of new fibre concrete dissipators based on the measurements performed on reinforced block ramps.

Although much research has been done in the area of the fire response of concrete in the past decades, only few studies are focused on the mechanical properties of air-entrained concrete at high temperatures. This paper presents preliminary results of an experimental investigation focused on the effect of air-entrainment on the compressive strength of concrete at various high temperatures. Within the scope of this work, heat treatments and compression tests have been performed on reference and air-entrained concrete specimens. The results obtained from the experiments have been analysed and show that the air entrainment seems to have an adverse effect on the compressive strength of the concrete at high temperatures when exposed for a prolonged period of time.

The environmental aspects of sustainable development in the construction industry consist in the utilization of secondary raw materials in a design and construction of new structures. The fact that China significantly reduced the import of plastic waste in 2017 raises the question of dealing with this waste in other states. A complicated recycling process of waste plastics puts pressure on scientific community to find new, more efficient ways of using this waste. The paper deals with the behaviour and mechanical properties of a completely innovative material called waste plastic-based concrete composed of natural aggregate and plastic waste which replaces cement as a binder. The completely unique composition of this concrete required to firstly test production technology and subsequently to conduct standard quasi-static experimental tests to obtain basic knowledge about the behaviour and mechanical properties of this composite. The obtained knowledge show that special attention must be paid to the production of the material which takes place under elevated temperature. The investigated composite has a relatively high tensile strength compared to conventional concrete and brittle fracture behaviour. In the next phases of the research the optimization of the production technologies and the composition of the composite will be provided.

The aim of this work is to design and fabricate bio-active concrete tiles which encourage rapid plant coverage of building walls and urban spaces with vegetation. A design comprises two different types of tile, which one of them intends to be used as a planter for a variety of climbing vegetation. Through the process of designing and manufacturing suitable mould for tiles, a complex macro pattern was developed to ensure water retention on the structural surface. The results of this work provide an alternative solution to the existing green wall systems by implementation of a bioreceptive cementitious material.

This paper describes the mechanism of radiation-induced deterioration of concrete and its components based on the literature review. The deterioration mechanism in different levels starting from the interaction between neutron and nucleus through the mineral metamictization and cement paste shrinkage up to the reduction of mechanical properties of concrete is explained in detail. All basic dependencies and patterns of volumetric change of minerals, aggregates, cement paste and finally concrete are also described in order to create a base for the future development of numerical models. Finally, the reduction of concrete mechanical properties is in correlation with its volumetric expansion. The radiation-induced volumetric expansion of concrete is affected by irradiation conditions (neutron fluence, neutron spectrum and temperature) and concrete composition (the amount, the proportion, the type and the structure of the minerals in the aggregate composition and the amount, the composition, the age and the structure of the cement paste).

The study specializes in the area of mechanical properties of select fibre reinforcement concrete. For the research fibre concrete reinforced with short steel fibres was used without bending. Fibre concrete is produced in the dosing 40 and 75 kg/m³. Laboratory program includes a complete group of tests, i.e. concrete compressive strength in cubes, three-point bending test, and split tension strength perpendicular and parallel to filling direction. Results are processed in summary, and they also include fracture-mechanical parameters needed for structural modelling. The research carried out found the positive influence of fibre on tensile strength and fracture energy. However, with more fibre, only fracture energy increases. It has also been found that the effect on compressive strength is small. For numerical modelling, the suitability of using a 3D computational model in combination with the fracture-plastic material model for fibre reinforcement concrete was verified.

Ventilated wall is an air-insulating method, which principle is to create a ventilated cavity along the surface of remediated underground wall (usually masonry). The paper describes an innovative solution of this remediation method based on the precast blocks made form textile-reinforced concrete - TRC. The main advantages of the solution (compared to traditional constructions - masonry, hollow bricks filled by cement mortar, monolithic concrete) are low labour difficulty, fast montage and high durability. Since the blocks are not structurally connected or anchored to remediated structure, it is a non-invasive method, which is also suitable for installation in historically valuable buildings. The technical solution is protected by patent CZ307501(B6).

This paper aims to describe the topic of origami folded plate structures and to design and built a small-scale model of such structure. To do so, firstly the properties of origami, in general, are discussed, then contemporary research of origami structures is described, and at last the concrete model is designed and built. During the work, the model was analysed with software and the process of building was experimentally tested on parts of the structure. The main outcome is a fibre reinforced concrete model of a bridge with a span of approximately 1.5 m, which competed in an international competition of FRC structures in Budapest in June 2019.

The concept of the self-healing concrete, thus an improvement of the durability of concrete structures, has become a widely investigated topic in recent decades. The aim of this study is to examine a possible combination of two existing approaches to the spontaneous crack-sealing – the biologically driven calcite precipitation and the addition of superabsorbent polymers (SAP) into the concrete matrix. Firstly, the paper compares the absorption rate of SAP in various solutions, including a nutrient-based solution which is used in the bio-concrete. The results show that the ionic composition of the liquid influence the swelling capacity greatly. In this study, the absorption rate of SAP in the nutrient-based solution is as low as 6% of the rate in distilled water. Thus, this finding could indicate a possible drawback of the combination of the proposed self-healing approaches. Further, this paper determines the impact of the SAP addition to cement paste with different water/cement ratios. In this experiment, the SAP is applied in various dosages (1% and 0.5% by c. w.) and states (a dry state or a fully swollen state). The conducted flowability and mechanical properties tests indicate a profound, generally negative, impact of the SAP addition on the cement paste characteristics. The paper then discusses possible adjustments of the SAP-cement paste composition and compares the present results with previous studies.

The paper is focused on visualization and analysis of concrete specimen damage after fire and blast experiments. A data visualization tool, based on an in-house MATLAB code, is described and its applicability and versatility are illustrated. In the first illustrative example, concrete spalling of fire exposed floor slab panels made of various types of concrete (without fibres, with polypropylene fibres, with steel fibres) is analysed. In the second example, the results of ultrasonic pulse velocity measurements of concrete bridge decks before and after blast experiments are shown in order to investigate the blast resistance of the decks made of different types of materials and to illustrate the damage of the decks in the form of the material degradation, surface spalling and puncture. The developed data visualization tool has been included in a freely available scientific computer program with a graphical user interface.

In extensive research, damage to concrete panels by explosion is investigated. For detailed monitoring of particular phases of explosion, exploitation of a high-speed camera is intended. The paper presents testing of possibilities of lighting of the scene at detonation with explosive agents. Four alternatives of agents were tested – three varying amounts of aluminium powder and argon. Paper presents results of the tests – intensity of lighting for tested variants, delay between ignition of lighting agent and the main detonation, and evaluates convenience of tested explosive agents for illuminating of the scene captured by high-speed camera.

The paper deals with the analysis of the effect of chosen latent hydraulic additives on concrete drying shrinkage. Variant dosage of latent hydraulic additives in cement paste was examined. Measuring of shrinkage in time was accompanied by testing of compressive strength and tensile strength at the age 28 days and 280 days. Results of investigations are summarized and compared.

Due to the increasing amount of waste tyres and also to their properties, it is necessary to look for suitable ways for their recycling. For production of rubber concrete, the crushed tyre rubber of fraction 0/4 and 4/8 was used for partial substitution of silica sand at the rate of 10 % by mass. For comparison, a reference concrete without rubber aggregate was also studied. Both natural and rubber aggregate were first assessed in terms of their physical parameters and thermal transport and storage properties. Evaluation of produced lightweight rubber concrete included measurement of basic physical properties, strength tests, and microstructural analysis. Thermal properties were studied from dry to fully water saturated state. The experimental results showed that concrete with a small amount of rubber aggregate had improved thermal insulation performance and can serve as an eco-friendly material for structural applications in civil engineering.

Textile reinforced concrete with non-woven polypropylene fabric has variable utilization for non-load bearing structures. One of the possible uses is production of facade panels or protective layers in the interior of buildings. For that reason it is important to determine fire resistance of this material. There was examined behaviour of specimens exposed to temperature in range 100 – 650°C for times from 5 to 60 minutes. Weight loss of the specimens caused by heating was also measured. Regardless to the relatively high moisture of material, the effect of spalling didn't occur.

Cracks in the concrete part of substructure are a problem in terms of penetration of water into the building. The best way is to prevent their development or support autogenous healing of concrete as much as possible. It is suitable to create many small specimens for research of crack evolution in various boundary conditions. TRC is applicable material for this research due to its compact dimensions and the ability to create a lot of cracks in relatively small area of the specimen. There are two basic methods how to create cracks in this material, tensile and bending loading. Each method provides different crack shapes.