bluuebunny/crossref_metadata_2025 huggingface dataset:
Filler from Expanded Glass as a Light-Weighing Component of the Cement Composite with Fiber Reinforcement
Authors: Čechmánek René , Prachař Vladan , Loskot Jiří
Published: August 2014

Bulk density reduction of the cement composite is possible by the means of using suitable light fillers in a matrix or porous structure creation with an air-entraining agent. Both ways are more or less suitable or effective for proper parameter achievement. From the range of possible fillers with different material properties and influence on rheological parameters during production granulated expanded glass worked the best. By the means of laboratory testing an effect of two fillers based on expanded glass on the fiber reinforced cement composite was verified. Practical applicability was tested in the production of commonly manufactured glass fiber reinforced concrete elements, such as channels for electrical cable deposition and products for urban equipment.
Properties of Concretes with Admixture of Natural Zeolite
Authors: Sedlmajer Martin , Hubáček Adam , Rovnaníková Pavla
Published: August 2014

Natural zeolite is one of the raw materials whose application can reduce the content of cement in concrete. The reasons for the constant reduction of the amount of cement are not only its economical demands but also a strain on the environment. The paper describes basic characteristics of concretes with increasing substitution of cement with zeolite. The designed concretes with natural zeolite are being compared with a reference concrete without zeolite.
Properties of Cement Based Composite with Fine Ground Recycled Concrete
Authors: Šeps Karel , Broukalova Iva
Published: August 2014

The paper contributes to sustainable building; it deals with the topics recycling of concrete waste and partial substitution of classical cement binder by more ecologically friendly binder made from waste materials. The investigations focused on hydraulic properties of micro-ground recycled concrete. Several mixtures were designed with the components: cement, ultra-fine ground recycled concrete and water. Testing specimens with dimensions 40x40x160 mm were elaborated and mechanical properties were tested. The results of tests are analyzed and influence of substitute binder evaluated.
Modified MDF Composites Intended for the Refractory Application
Authors: Másilko Jiří , Bartoníčková Eva , Novotný Radoslav
Published: August 2014

Paper deals with the preparation and characterization of MDF composite based on the strontium-aluminate cement. MDF composites show enhanced mechanical properties, especially flexural strength. Strontium-aluminate cement has got good thermal stability and capabilities at very high temperatures. MDF composites based on strontium-aluminate cement in combination with polyvinylalcohol were prepared by "high shear mixing" method. The prepared samples were subjected to high temperature solid state reaction at various temperatures. Characterization of MDF samples was mainly based on the methods of testing the flexural strength, X-Ray diffraction and thermogravimetry coupled with differential thermal analysis.
Effect of Water-Soluble Carbon Nanotubes on the Mechanical Properties and early Hydration of Alkali-Activated Slag
Authors: Rovnaník Pavel , Bayer Patrik
Published: August 2014

Alkali-activated slag (AAS) is a material which has great potential for use in building industry. The aim of this work was to gain new superior properties by the addition of carbon nanotubes (CNTs). This material can act as a microreinforcement improving mechanical properties of cementitious materials. The effect of 0–1 wt.% addition of CNTs on the mechanical properties, hydration characteristics and microstructure of AAS binder was determined. The addition of CNTs delays the setting of the binder and a partial deterioration of strength parameters was observed.
Preparation of Alternative Hydraulic Binder Based on Secondary Raw Materials
Authors: Švec Jiří , Opravil Tomáš , Másilko Jiří
Published: August 2014

Reusing and recycling of secondary raw materials from high-volume industrial productions (especially form construction materials and binders fabrications) is very important way of conserving environment and it is also interesting from the economical point of view. The production of common hydraulic binders, especially Portland cement, burdens the environment with considerable amount of combustion gases and consumes energy in massive scale. Alternative (low – energy) binder can be used as Portland cement substitution in applications with lower mechanical properties requirements. Mined limestone wash sediments contain large amount of clay components, but there is also indispensable share of fine calcite. This composition makes these sediments a promising material for the preparation of hydraulic binders as Roman cement or hydraulic lime.
Influence of Industrial By-Products on Shrinkage of Alkali-Activated Slag
Authors: Bílek Jr. Vlastimil , Kalina Lukáš , Bartoníčková Eva , Opravil Tomáš
Published: August 2014

One of the highest shortages of alkali-activated slag (AAS) is high shrinkage, both autogenous and drying. One of the possibilities of lowering the shrinkage is partial replacement of slag by suitable admixtures, which can act for example through the forming of expansive hydration products. In this study, 0–50 % of slag was replaced by by-pass cement kiln dust and fluidized bed combustion fly ash. Promising results were obtained especially in the case of fly ash. By using admixtures at higher dosages compressive strengths were reduced.
Modelling of Influence of Heat Curing on Mechanical Properties of Fly-Ash Concrete Mixtures
Authors: Váchal Tomáš , Šulc Rostislav , Svoboda Pavel
Published: August 2014

This paper describes influence of heat curing on development of mechanical characteristics of concrete mixtures based on alkali activated fly-ash (POPbeton). One of the major influences for the correct treatment of alkaline activation is the quantity of heat energy in a given time period which is supplied during activation. The paper describes the dependence of development of compressive strength of POPbeton on the time and temperature of heat curing. A predictive model was assembled which describes the dependence of the supplied heat energy over time on the resulting characteristics of POPbeton. The result is a tool that can predict the resulting values of mechanical characteristics of test samples of POPbeton. The final goal of this project is the transfer of alkali activated fly-ash from big coal power plants into building industry.
The Effect of Boron and its Compounds on Setting of Portland Cement
Authors: Kratochvíl Jiří , Opravil Tomáš , Diviš Pavel
Published: August 2014

The aim of this work is to study the influence of boron and its compounds, boric acid and borax, on the hydration of Portland cement. The samples – cement paste modified by the addition of boron, borax and boric acid in different concentrations were prepared. The results are obtained from the evaluation of calorimetric curves, mechanical properties and phase composition. The goal is to describe the kinetics of targeted retarded process of hydration and to find such addition which would suspend the setting of boron modified system entirely. The comparison of effects of each boron-containing compound is based on its concentration and on its kind.
Behavior of Class C Fly Ash during Firing at High Temperatures
Authors: Vodová Lucie , Sokolař Radomír
Published: August 2014

Fluidized fly ash (class C according to ASTM) from thermal power plants Hodonin and Ledvice and stoneware clay B1 were used in the experimental work dealing with SO2 emissions during the firing at 1200°C. The aim of the work was to define the temperature at which sulphur dioxide begins to leak, and the leakage rate of SO2. It was found that temperature of decomposition of anhydrite depends on particle size. For milled fly ash is this temperature 150°C lower than for unmilled ashes. The addition of clay also decreases the temperature of decomposition. Sulphur dioxide begins to leak at 975 °C for samples with 40% addition of fly ash.
Utilization of Materials from the Production of Mineral Wool into Construction Materials
Authors: Leber Pavel , Čechmánek René , Bibora Petr , Chromková Ivana , Vyvážil Martin
Published: August 2014

This paper describes research on utilization of solid waste materials from mineral wool production. Aim of this research is verification of most suitable way of separated waste material utilization in building materials and determination of its maximal amount without negative effect on physical-mechanical and ecological characteristics of a final product. The research was focused on self-leveling mixtures, thin-walled glass fibre reinforced concrete products and vibropressed thin-walled shaped concrete blocks.
Concrete with High Content of Fly-Ash for Common Use in the Czech Republic
Authors: Sachova Hana , Huňka Petr , Kolisko Jiří , Rehacek Stanislav , Citek David
Published: August 2014

Concrete with high substitute of the cement with fly-ash (FAC) is favourably used for structures with undesirable development of hydration heat or where reduction of the share of Portland clinker in the adhesive provides better resistance of concrete against impacts of acidic aggressive environment. Due to pozzolanic reaction fly-ash participates on formation of cement or adhesive stone and contributes to increased strength of concrete. As the pozzolanic reaction process is gradual its impact on the increased concrete strength is shown within longer time horizon (i.e. after lapse of standard age) and fly-ash concretes are therefore characterized by a short-term low strength which is one of its disadvantages mostly during winter season. However during summer season concretes with partial substitute of cement with fly-ash are beneficial solution for common use even from the aspect of reduced material costs on concrete production. Reduced cement volume in the concrete is nevertheless limited by requirements of ČSN EN 206-1 on concrete composition which is making difficult launch of concrete with higher cement substitutions with fly-ash on the Czech market. FAC allow effective use of the fly-ash, which is otherwise a waste product representing environmental load on spoil heaps as a substitute of clinker, the production of which is also environmentally loading from the power and raw materials aspect. This environmental input of FAC would be hopefully more considered for design of building structures in the future.
Quantification of Micro-Cracks by Acoustic Emission Method during Setting and Hardening of Concrete
Authors: Topolář Libor
Published: August 2014

As a non-traditional, non-destructive analysis method, the Acoustic Emission Method was used for civil engineering experiment. Concrete is a composite construction material frequently used in civil engineering. We know that concrete is like a man – when concrete is made it is like a baby, then it ages and its properties change in accordance to its baby life. That means it is better to monitor and change its properties when it is young as soon as possible. However, using methods immediately after concrete birth (making the mixture) is difficult. The main aim of the article is to show the application of Acoustic Emission Method during concrete lifetime, particularly during the first days after mixing the mixture. Article describes monitoring concrete structure for 20 days since their making up. Primary interesting part is during first day of hardening. Acoustic Emission Method has used for monitoring both samples. Expected result has been between covered and uncovered specimen.
Combination of Various Admixtures as Partial Replacement for Portland Cement and the Influence on the Final Concrete Properties
Authors: Křížová Klára , Hela Rudolf
Published: August 2014

The article discusses the physical mechanical concrete properties of five different concrete recipes. The objective of the composition of the concrete is to use the lowest quantity of Portland cement by adding additives (fly ash, slag and limestone) and the various combinations.
Masonry Cements with Fines from Aggregate Production
Authors: Brožovský Jiří
Published: August 2014

Masonry cement consists of Portland cement, inorganic materials and optional additives. Natural mineral materials are included in inorganic materials. The paper states knowledge gained during research of properties of masonry cements in which fine parts originating in production of aggregate of two types – amphibolite and grandiorite – were used as inorganic content. If the content of fine parts in cement is from 50% to 75%, masonry cement of strength marks 5 and 12.5 can be produced.
Measuring of the Penetration Rate of Injection Gels during Remediation of Various Building Materials
Authors: Drochytka Rostislav , Melichar Jindřich , Dohnálek Pavel
Published: August 2014

One of the most widespread method of redevelopment of wet masonry is additional creating of hydro-insulating screen in the material. This method has many advantages. In comparison to other procedures its application is quick, easy and has excellent final efficiency. Main object of this article is observing dependence of functionality of various injection gels in different types of masonry on conditions and states of their being.
Development of Thermal Insulating Plasters with Regulated Capillary Activity
Authors: Zach Jiří , Hroudová Jitka , Reif Martina , Korjenic Azra
Published: August 2014

The development of prospective, thermal insulating plasters that are applied during the reconstruction and rehabilitation of structures has taken place at the Faculty of Civil Engineering for many years. The main objective of the research work is to achieve the best ratio of thermal and mechanical properties, including high porosity. During the development of this test, testing recipes were tested, which were often used as alternative input materials. On the basis of the achieved results, optimal recipes were proposed with the stated requirements for heat insulation, mechanical properties and porosity. Due to the fact that during the reconstruction this often concerns structures loaded by increased structure, then such materials must have high open porosity. The article describes the study of moisture behaviour, particularly capillary activity for light thermal insulating plasters with the use of alternative raw material sources.
Study of Heat Transfer Process in Structure of Thermal Insulating Materials Based on Natural Fibers
Authors: Zach Jiří , Hroudová Jitka , Sedlmajer Martin , Korjenic Azra
Published: August 2014

Natural fibre based thermal insulating materials belong to progressive building materials representing one of the possible ways in sustainable development and which are characterised with low carbon trace and low value of primary bound energy. In case of industrially produced insulating materials (for instance using thermal connection method) the insulating materials based on natural fibres showed comparable properties with industrially produced insulating materials on building markets. In the view of thermal insulating properties the natural insulating material show slightly different behaviour in comparison with synthetic insulating materials which is caused by fibrous structure of insulating materials and low thermal conductivity of natural fibres (contrary to glass or mineral fibres). The paper describes results of research oriented on study of heat propagation within materials based on natural fibres originated from agriculture and stockbreeding.
Utilization of XPS Analysis for the Characterization of Mechanochemical Activation in Polymer-Cement Composite Materials
Authors: Kalina Lukáš , Matoušek David , Šoukal František
Published: August 2014

This paper introduces the X-ray photoelectron spectroscopy (XPS) technique, well applicable for the analysis of the interfacial layer between polyvinyl alcohol and monocalcium aluminate in macro defect-free (MDF) cement. The experimental results explain the chemical reaction mechanism during the mechanochemical process, which is crucial for the formation of those non-traditional polymercement composite materials.
The Occurrence of Cyanobacteria and Green Algae on Facades of Historical Sacral Buildings
Authors: Wasserbauer Richard , Rácová Zuzana , Loušová Ivana , Lecák Marek
Published: August 2014

The study investigates the microflora of the facades of two towers of historical sacral buildings whose surface was cleaned by water blasting. Lime or lime-cement plaster in both buildings was gradually replaced by silicone facade paint in the finale of renovation work. Following the above treatment, the facades were monitored for the growth of phototrophs, heterotrophic bacteria, micromycetes, and pH levels as a sign signalling the silicone paint degradation.
Assessment of Bond Behavior of UHPC and Prestressing Strands
Authors: Citek David , Vitek Jan L. , Kolisko Jiří , Huňka Petr , Rehacek Stanislav
Published: August 2014

Ultra High Performance Concrete - UHPC is a relatively new type of composite material with outstanding features (high compressive strength, high tensile strength and high durability). Also the bond strength between steel reinforcement and UHPC is better than that in ordinary concrete. This fact needs to be quantified, because no standard prescribes the bond behavior of UHPC and design of UHPC in general. The main aim of the experimental research was to determine the average bond stress between prestressing strands and different types of UHPC. The second aim was to show very significant increase of the average shear stress in bond of UHPC compared to that of ordinary concrete. In order to determine the bond capacity, two types of experimental specimens – parts of prestressed girders and specimens prepared according to standard, were tested in the laboratory. The specimens were prepared for pull out test, in which the prestressing strand is pulled out from the cube or part of girder made from UHPC. The tensile force in strand and slip of the end of reinforcement were measured and then the average bond stress was examined. The influence of different material properties and different anchorage lengths of prestressing strands to bond behavior of UHPC was examined and results were compared to these phenomena of ordinary concrete. The results of bond test led to the conclusion that the application of UHPC can significantly reduce the anchorage length of reinforcement compared with that in ordinary concrete.
Application of Scanning Electron Microscopy for the Purposes of Mineralized Wood Survey
Authors: Murínová Tereza , Mamoňová Miroslava , Mec Pavel , Daňková Jana , Rezek Petr
Published: August 2014

Wooden mineralization is a familiar term that indicates mainly natural process during which chemical changes of the material arise by specific conditions and mineral particles remain in the lumen of wooden cells or penetrate into the cell wall, where they can bind with some components. This principle can be also used for chemical modification for the purpose of extending the life of wooden elements. This study was focused on the survey of artificial mineralized wood by scanning electron microscopy (SEM). Evaluation of the SEM images aimed at structural changes of wood and localization of mineral particles is the key knowledge, which can serve for the determination of mineralization extent.
Surface Treatment of Concrete Roof Tiles
Authors: Solný Tomáš , Kosár Petr , Kalina Lukáš
Published: August 2014

Therein the application of special inorganic binders onto a freshly prefabricated surface of concrete roof tiles for the purpose of improving the quality of surface properties is reported. The possibilities of preparation of polymer-cement matrix with improvement gained from plasticizers are discused to obtain sprayable coating for roof tiles. Use of sprayable coating leads to smoothing of surface defects generated from previous processing of roof tiles thus improving the quality of surface leading to better durability of roof tiles with just a low increase of manufacturing cost.
New Method for (Nano)Micro-Characterization of Materials - Correlative Microscopy
Authors: Wasserbauer Jaromír , Zmrzlý Martin
Published: August 2014

New building materials must meet strict requirements on mechanical properties. Therefore structural and chemical characterization of new building materials is very important. The correlative microscopy is a new possibility of materials analysis. This method combines light microscopy (LM) and scanning electron microscopy (SEM). LM images can be then precisely extended by their morphological background and/or material distribution, e.g. with energy dispersive spectroscopy (EDS). With using correlative microscopy, the weakest places of alkali-activated concrete were found.
High Performance Concrete Experimental Structure
Authors: Fladr Josef , Kohoutková Alena
Published: August 2014

An experimental structure from high performance concrete was created within the scope of long-term research and development program of the Department of Concrete and Masonry Structures, Faculty of Civil Engineering, CTU in Prague that is focused on advanced cementitious composites. The intention was to build a structure of so called “CyclePoint” (resting place for bikers) interesting from architectural point of view and made from non-traditional, high durability material. Transfer of high performance concrete composition designed in the laboratory to the mixing plant construction company was accomplished. This required series of confirmation material tests. The technology of casting high performance concrete into the formwork of thin-walled precast elements was optimized. The use of engineered mix of fibres enabled the authors to design structures without main rebar reinforcement. The design was carried out using finite element based software and verified by loading experiments executed on structural elements in full-scale.
Technology of Production of SFRC at Concrete Plants
Authors: Ráček Václav , Vodicka Jan
Published: August 2014

Currently, manufacture of steel fibre reinforced concrete (SFRC) takes place in concrete mixer truck for floors mostly of industrial halls. This technology is suitable for low dosages of fibres (about 20kg/m3), which is determined by uncrossable price of deposited concrete (400 – 600 crowns/m2 for the floor in thickness from 150 to 200 mm). Totally realistic premise in future is, that SFRC will be used for load-bearing SFRC structures of aboveground objects. In this case, production of SFRC must take place in concrete plants at higher weight doses than 40 kg/m3 of fibres, to achieve the characteristics of SFRC, which bring effects to SFRC structures. In the paper, there are presented two examples of the production of SFRC in concrete plants. There is specified manufacturing process of production of SFRC in mixers with forced circulation, which is necessary to comply, in order to achieve a homogenous fresh fibre concrete and to minimize wear of machinery.
Recycled Poly(Vinyl Butyral) Used as a Barrier to Prevent Mortar Carbonation
Authors: Tupý Michael , Štefková Daniela , Sotiriadis Konstantinos , Krmíček Lukáš , Carbol Ladislav , Petranek Vít
Published: August 2014

The paper deals with testing of CO2 diffusivity through poly (vinyl butyral) (PVB) layers and their efficiency to serve as barriers against cement mortar carbonation. Two different types of PVB were tested; PVB sheet made from original extruded PVB polymer and PVB sheet made from PVB dispersion obtained from recycled windshields. The first part of the work was focused on testing CO2 diffusion when polymer sheets were exposed to a CO2 atmosphere (10% v/v CO2) with 0% RH. The excellent barrier capability against CO2 permeability of both types of polymer layers was observed. In the second part, mortar specimens were exposed for 23 days to two different carbonation regimes (laboratory conditions and chamber with CO2 atmosphere (1% v/v CO2) and 60% RH), having been coated or not with recycled PVB dispersion. Compressive strength tests, carbonation depth measurements and acoustic measurements (impact-echo method) were performed. The results showed the alternation of the compressive strength values depending on whether PVB coating was used or not. Both phenolphthalein test and impact-echo method confirmed the protective effect of PVB layer against mortar carbonation.
An Experimental Study on Acoustic Emission Signals during the Three-Point Bending Fracture Test
Authors: Matysík Michal , Topolář Libor , Daněk Petr , Šimonová Hana , Vymazal Tomáš , Plšková Iveta
Published: August 2014

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture test of specimens of concrete. Much has been said in literature about the fracture energy of concrete and its importance. Acoustic emission is an experimental tool well suited for monitoring fracture processes. Quantitative acoustic emission techniques were used to measure micro fracture properties. For three different concrete mixtures typical acoustic emission patterns were identified in the acoustic emission records to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviours. The results obtained in the laboratory are useful to understand the various stages of micro-cracking activity during the fracture process in quasi-brittle materials such as concrete and extend them for field applications.
Plaster Pigments in Traditional Folk Architecture - A Case Study from Moravia (Czech Republic)
Authors: Všianský Dalibor
Published: August 2014

The results of analyses of coloured plasters are given in the paper. The samples come from traditional folk earth houses from SE and Central Moravia and were chosen so as all of the most common colours of the Central European folk architecture are present among them: red, yellow, blue, green, and black. The analyses were conducted by the means of light microscopy, which is also a powerful tool for stratigraphical analyses, X-ray diffractometry, Raman spectrometry, end electron microanalysis. Hematite of industrial origin was identified as the red pigment, the yellow one was formed by yellow earth, which also may be a precursor for traditional production of red dye. The widest used blue pigment was ultramarine in the 19th and the first half of 20th century in Moravia. The analysed green pigments were formed by an organic dye of green earth and the black one consisted of soot. Based on the sort and composition of pigment and plaster, the age of the material is also discussed.
Study of Heat Transport in Structure of Concrete
Authors: Bodnárová Lenka , Hroudová Jitka , Zach Jiří , Nováková Iveta
Published: August 2014

Current trend of construction of ring roads in large cities going often underground emphasizes safety of implementation and using of such constructions, which is closely connected to possible risks of a fire in these predominantly monolithic structures made from steel reinforced concrete. The paper gives results of the research focused on thermally-technical properties of cement based composite materials resistant to high temperature suitable for application in places with higher risk of fire, like secondary lining of tunnels or underground car parks. The aim was verification of appropriateness of testing mix-designs for application in structures possibly endangered by fire.
Determination of Reflectance of Some Decorative Stones
Authors: Pospíšil Martin
Published: August 2014

This paper describes a simple methodology for determining the light reflectance of some natural stones used in architectural practice. The methodology is based on the interpolation of the value lying between two etalons for which the reflectance of light was precisely measured under laboratory conditions. For field measurements there were two illumination chambers constructed; in these chambers indirect daylight was transmitted to a stone surface. Reflectance of light from the stone surface was then measured by a luxmeter in a predetermined constant height and the result was interpolated between the values ​​of both etalons. In copending case study 300 measurements on fifteen samples of stones were performed in this manner and resulting coefficient of reflectance of light was then calculated. Resulting coefficient is applicable for the calculation of daylighting of buildings according to the standard CSN 73 0580.
Properties of Lightweight Thermal Insulation Plasters
Authors: Sedlmajer Martin , Zach Jiří , Hroudová Jitka
Published: August 2014

The design of thermal insulation plasters is closely connected with their apparent density and the binder used where low apparent density may fetch very good thermal insulation properties. What matters is the correct composition of the plaster mix system being designed. The choice of binder, other components and especially aggregate taking up a dominant part in the system is also important. A suitable aggregate is expanded obsidian which has very low density with open pore structure which has positive influence on thermal insulation properties.
Reduction of Efflorescence in the Alkali Activated Systems
Authors: Suchý Rostislav , Pořízka Jaromír , Wasserbauer Jaromír , Kalina Lukáš
Published: August 2014

Alkali metal cations are bound weakly in the structure of alkali activated materials. This fact causes the formation of undesirable efflorescence in humid environment. In this work, the effect of fluoride additives, which reduce significantly the efflorescence, was investigated. The chemical mechanism of selected additive in the modified binder was studied based on XRD, SEMEDX and ICPOES analysis. Also the effect of added fluorides on the mechanical properties of final product was monitored.
The Strength of Masonry with Low Compressive Strength of Mortar
Authors: Lorenz Karel , Pospíšil Martin
Published: August 2014

The article deals with a problem of determination the strength of masonry for low grade mortar. This situation can occur with fresh mortar or in historical massive buildings. Results of different equations according to several authors and standards were compared and expressed in graphs. Authors propose the minimum value of mortar strength being used in equation according to Eurocode 6 to obtain reasonable strength of masonry with so called “zero” mortar.
Use of Composite Elements for Monitoring of Concrete under Loading
Authors: Junek Jiří , Čechmánek René , Nešpor Bohdan , Steffan Pavel
Published: August 2014

The object of our project is a design and verification of composite elements of defined shape with effective content of carbon particles and fibers. These composites should be able to monitor internal state of selected structural elements in order to eliminate negative effects of loading.
Mechanical Fracture Parameters of Fine-Grain Concretes with Zeolite: Effect of Composition and Origin of Cements
Authors: Šimonová Hana , Schmid Pavel , Keršner Zbyněk , Rovnaníková Pavla
Published: August 2014

This paper introduces results of fracture experiments on fine-grain concrete specimens prepared from CEM 42.5 R Portland cement of different origin (five Czech Republic localities: Mokrá, Hranice, Radotín, Prachovice, Čížkovice), with natural zeolite admixture. Although the specimens were produced using the same type of cement, this paper shows that even small differences in chemical and mineralogical composition (caused by different origin) can result in changes of mechanical fracture parameter values.
Influence of Moisture and Temperature of Calcium Silicate Bricks on Results of Measurements with Rebound Hammer
Authors: Brožovský Jiří
Published: August 2014

Testing with rebound hammers is influenced by various factors, like composition and components of tested material, treatment of tested surface, moisture content of tested material, temperature of material and environment. Influence of these factors on measurement results during testing concrete is described in technical literature and standards. Calcium silicate body can be characterized as non-cement based fine grained concrete, however, with considerably higher water absorbing capacity compared to standard concrete: ca 12-14% (fine aggregate bonded by hydration products of lime). To use rebound hammers for testing calcium silicate bricks, influence of selected factors on measurement results was tested. It was proved, that content of moisture and temperature of calcium silicate brick has influence on results of measurements with rebound hammer, and therefore it is necessary to take into account these influences.
Monitoring the Influence of Dehydrating Solutions for the Production of Alpha Gypsum
Authors: Dvořák Karel , Hájková Iveta , Havlíčková Kateřina
Published: August 2014

The research work is focused on the preparation of alpha hemihydrate of calcium sulphate without pressure by dehydration of gypsum in chloride salt solutions. In relation to the previous work, the influence of dehydrating solutions on the final properties of the produced alpha gypsum was monitored. Chemical and mineralogical analysis and determination of physical mechanical properties of the final product were conducted.
Laboratory Preparation of a Ternary Binder System
Authors: Hlavinková Eva , Fridrichová Marcela , Gazdič Dominik , Havlíčková Kateřina
Published: August 2014

Currently, the binders of self-levelling mixtures are most commonly implemented as one-component or two-component (binary) systems. One-component systems are usually Portland cement or alumina cement alone, both further modified especially by plasticizers and dispersive additives. In addition to their indisputable advantages, one-component as well as binary systems have some drawbacks including worse technological properties in the case of one-component systems based on Portland cement and higher financial costs in the case of binary systems which are usually mixtures of anhydrite II and α-gypsum. These deficiencies should be addressed by a ternary system which represents a compromise between the quality and affordability of existing systems. The basis of this ternary system is Portland cement to which an expansion agent composed of alumina cement and gypsum or dry hydrate is added. In this system, it is expected that the required strength and volume stability will be provided by Portland cement and the expander, respectively. The aim of this work is to study the ternary binder system based on Portland cement, alumina cement and gypsum or supplementary non-traditional connective components for use in the industrial production of self-levelling mixtures.
Effect of Mechanical Activation on Properties of Alkali Activated Binders
Authors: Sisol Martin , Mosej Juraj , Drabová Miroslava , Brezani Ivan
Published: August 2014

Effect of mechanical activation of fly ashes on strength of alkali activated binders is investigated. Four different kinds of fly ashes are mechanically activated. The aim of mechanical activation is to increase the reactivity of fly ashes. Mechanically activated fly ash is used as an admixture to the untreated original fly ash in proportion of 0, 50, 75 and 100 %. Fly ashes are alkali activated with solutions containing sodium hydroxide and sodium water glass. Compressive and flexural strength is tested on hardened alkali activated binders.
Potential Application of Belite Clinker
Authors: Staněk Theodor
Published: August 2014

Blended cements were prepared from belite clinker burned in a model kiln and ordinary industrial alite clinker. The mechanical and physical properties of these blended cements were determined. The difference in the development of hydration heat of belite and alite cements by using calorimetric method was determined also. The results show that strengths of prepared belite cement after 28 days of hydration are equal to those of industrial alite cement. Short time strengths are suitable for blended cements up to 30 % content of belite clinker. These results demonstrate the possibility of separate industrial belite clinker production next to common alite clinker manufactory and production of economically and ecologically advantageous blended Portland cements with suitable technological properties.
Workability Assessment of the Mixture for the Production of Cement-Bonded Particleboards with Modified Composition
Authors: Bydžovský Jiří , Melichar Tomáš , Konečný Dalibor , Keprdová Šárka
Published: August 2014

The paper discusses the examination of suitability of a newly proposed method for testing the consistency of fresh mixture for cement-bonded particleboards (cement-chip boards) with modified composition. A modifier component was dusty waste – a by-product from the production of cement-bonded particleboards and blast-furnace slag. The proposed method is based on a combination of vibration and static pressure with a defined mass. Within the conducted research, we have found that this method requires a slight modification in order to be used for more accurate assessment of the workability of fresh mixture of cement-bonded particleboards.
Study of Parameters of New Polymer-Cement Composites after Exposure to Extreme Temperatures
Authors: Melichar Tomáš , Bydžovský Jiří , Keprdová Šárka
Published: August 2014

The paper focuses on the study of parameters in newly developed polymer-cement mortars designed for applications in environments with a potential stress by extreme temperatures. Recipes of repair mortars intended for redevelopment of steel-reinforced concrete structures were designed and tested.
Study of Ballistic Textiles Based on Ultra-High Strength Fibres
Authors: Mikulíková Regina , Křesťan Jan , Dvořák Aleš , Rolc Stanislav , Krátký Josef
Published: August 2014

The work is focused on mechanical and ballistic properties of textile materials most used in personal protection (ballistic vests, helmets), i.e. aramid fabrics. Physical and mechanical properties such as Young’s modulus, maximum strength before rupture, tensile strength, elongation at rupture and combustion velocity were measured. Ballistic resistance of sets of selected fabrics was tested. Ballistic tests were focused on protection level TBO-2/CZ according to ČSN 395360. Differences in physical and mechanical properties of commercial fabrics used as inner soft armour and fabrics used for trauma effect reduction were observed. It was found out that different order and combination of different types of textile fabrics influence significantly the ballistic efficiency of fabric sets.
Benefits of RES Use in Brownfields Reuse in Slovak Municipalities
Authors: Bakalár Tomáš , Pavolová Henrieta , Weiss Erik
Published: August 2014

The issue of renewable energy in revitalizing brownfields is currently important especially in the development of individual municipalities. Reuse of brownfields in terms of municipalities in Slovakia, which represent economically devastated buildings or the territories used inefficiently, with a strong negative impact on the wider environment of municipalities, requires cooperation of the state and the public sector with private sector businesses. The article points to the possibility of using selected renewable energy sources in removing negative aspects caused by the existence of brownfields in the territory of south-eastern Slovakia. It stresses on the benefits of addressing this issue in the proposed model of evaluation of renewable energy recovery and reuse of brownfields.
Life Cycle Assessment of Timber Formwork: Case Study
Authors: Krišták L'uboš , Igaz Rastislav , Brozman Dušan , Réh Roman , Šiagiová Petra , Stebila Ján , Očkajová Alena
Published: August 2014

The article deas with evaluation of the selected parts of a life cycle of timber formwork on a wooden basis, notably in the field of manufacturing and usage. Experimental research focused mainly on assessing the possibilities of energy savings in a manufacturing process through shortening a technological process of moulding. By optimalisation of a moulding period, it is possible to achieve considerable energy savings. Based upon the experiments, we created an experimental model in order to determine optimum moulding time. Withing a process of usage, we evaluated particular materials with regard to re-use cycle based upon the experience of commercial manufacturers.
Rheological Properties of Asphalt Mixtures with Additives Based on Renewable Sources
Authors: Schlosser Frantisek , Ďureková Dominika
Published: August 2014

The deformational properties and fatigue of asphalt layers are important for the design and assessment of semi-rigid and flexible pavements. The Two-point Bending Test was used for determination of deformational characteristics of asphalt mixtures on Department of Construction Management in Žilina. The results are evaluated with the KATEMS assessment software. The long-term research leads to estimation of deformational characteristics and fatigue of different types of asphalt mixtures. The tests have shown a positive impact of additives (ground rubber, hydrate lime component, recycling materials,...) on the results of these mixtures. This article is focused on assessment of deformational properties and fatigue of selected types of asphalt mixtures, there are viscoelastic materials in construction of pavement.
Selected Properties and Shrinkage Compensating Effect by Injection Moulding of Origin and Recycled Thermoplastic Composites with Polypropylene (PP) Matrix, Talcum and Glass Fiber
Authors: Krzyżak Aneta , Drabik Marcin , Zyśko Łukasz , Dulebová Ľudmila
Published: August 2014

This article explains and demonstrates how to first and second injection moulding influence to shrinkage effect of polypropylene composites with talcum and cutting glass fiber. Results show that the longitudinal and transverse shrinkage changed by differend parameters of injection moulding. It was observed shrinkage compensating effect occurring at composite molded parts with a high glass fiber content. Recycling process has reduced the shrinkage and tensile strength. Caused an increase in elongation, but it has not noticed any major changes in the hardness of injection molded parts.
Study of Selected Natural Materials Ignitability
Authors: Martinka Jozef , Hrušovský Ivan , Chrebet Tomáš , Rantuch Peter
Published: August 2014

This scientific study deals with a complex research of initiation process of selected natural materials. The first chapter deals with research of the influence of density and thermal modification of spruce wood (Picea abies(L.) Karst.) on the critical heat flux density for the pilot ignition. In this chapter the thermally modified and unmodified samples of a spruce wood were investigated. The thermally modified samples were prepared according to temperature program for the ThermoWood - Thermo-S (maximum temperature during the thermal modification was 190 °C) and ThermoWood - Thermo-D (the maximum temperature during the thermal modification was 212 °C) production. Critical density of heat flux was determined on a cone calorimeter test by procedures in accordance with ISO 5660-1:2002. The obtained results showed that the thermally modified spruce wood in comparison with the thermally unmodified one had higher critical density of heat flux. The second chapter is aimed on determination of ignition activation energy of pure cellulose, cellulose impregnated by water solutions of KHCO3and (NH4)2HPO4with concentrations of 5, 10 and 15 wt. % and on determination of ignition activation energy of dust from beech wood (Fagus sylvaticaL.). The activation energies were determined in accordance with isothermal, dynamic and non-isothermal model-free methods. The obtained results showed that the ignition activation energy of cellulose impregnated by water solutions of KHCO3and (NH4)2HPO4have lower activation energy than the pure cellulose. The obtained data on the activation energy of beech wood dust showed that the activation energy depends significantly on the degree of conversion. Chapter three deals with the research of inclination of selected vegetable oils (Linseed, Sesame and Sunflower oil) applied to cotton to self-ignite. The propensity towards spontaneous combustion of the mentioned oils was investigated by Mackey test and Accelerating Rate Calorimetry. The results showed that the ratios of oil mass to the mass of the carrier, on which oil is applied, had significant impact on the propensity of vegetable oil to the spontaneous combustion. The highest propensity to spontaneous combustion of the investigated materials showed the Linseed oil.
An Analysis of Factors Affecting Available Safe Escape Time
Authors: Mózer Vladimír
Published: August 2014

This paper deals with some of the parameters that affect the available safe evacuation time (ASET), including fire growth rate, enclosure area, and thermal properties of the bounding construction. Although the available safe escape time is a crucial design parameter, it is, or has to be, often generalised to cover a range of scenarios; this is also the case of design codes. It is therefore necessary to be aware in which aspects such generalisation is possible. A set of computer model cases, carried out in CFAST, is analysed and the effect of individual variables quantified. As real fires usually grow exponentially with time, the t2-fire model was used, employing the standard fire growth rates. By analysing the computer model scenarios, it was found that increasing the size of the enclosure does not bring proportional growth of available safe escape time. It is the rate of fire growth that is the primary factor affecting the safe available escape time. Two different smoke layer height tenability criteria – 0.9m and 1.5m – are also compared; the first derived from literature and the latter represent a more conservative estimate.
Determining of Damages Caused by Fire on Photovoltaic Power Stations
Authors: Kadlec Zdeněk , Kvarčak Milos , Thomitzek Adam , Trčka Martin
Published: August 2014

The fire produce harms and damage environment. The fire assessment of photovoltaic power stations is based on testimony, photographic and some next records of during fire, data recorded by Weather Station of photovoltaic’ s station and from inspection of fireplace after extinguishing of fire.
Evaluation of Thermal Degradation of Wood with Environmentally Problematic Application of Coatings
Authors: Ružinská Eva , Mitterová Iveta , Zachar Martin
Published: August 2014

For predicting the behavior of wood products with a final finish by applying polyurethane coatings (mainly solvent) under realistic conditions of use is extremely important to monitor all quality characteristics (physical, mechanical, chemical and performance) as well as fire-engineering based on selected characteristics of thermal degradation The paper presents proposals evaluation criteria (total weight loss, maximum rate of burning, time to reach maximum speed of burning, ignition time) for test radiant heat source for wood surface finishing materials by polyurethane coatings for a comprehensive assessment of fire-technical and environmental safety materials for predicting the behavior of these materials in response to fire.
Fire Safety and Security Threats Identification and Elimination
Authors: Mózer Vladimír , Loveček Tomas , Vel'as Andrej , Makovická Linda
Published: August 2014

This paper deals with the topic of fire safety and security measures and their mutual interaction. A designer or stakeholder may be confronted with conflicting objectives regarding life safety and object security. Often, escape routes pass via areas that are under non-emergency conditions subject to access control, accessible only to members of staff, contractors, etc. When fire alarm is activated, it is necessary to provide fast and unhindered evacuation from the premises, which may involve using restricted-access back-of-house areas. On a case study – section of a shopping centre – the concepts of both fire safety and security are presented. Firstly, the areas are analysed in terms of their importance from life safety and property security points of view and subsequently solutions are proposed to address any issues. In certain cases a balance between safety and security requirements must be found, i.e. it is not possible to fully satisfy both objectives at the same time, whereas in other fire safety and security systems have been found mutually complementary.