Artur ŁAGOSZ Adrian Iwo SOWA
INFLUENCE OF SLAG SPECIFIC SURFACE ON PROPERTIES OF HIGH-STRENGTH MORTARS
The paper presents the results of the investigations into properties of high-strength mortars based on different binders: Portland cement, Portland cement blended with silica fume, binders with 20% or 40% of cement replaced with ground granulated blast furnace slag. It was shown that replacement of cement with slag leads to equal or even better mechanical properties compared to plain cement binder, or cement blended with silica fume, even after 7 days of curing. The above takes place for lower cement replacement and high specific surface of GGBSF. Utilization of slag with low specific surface causes lower strength properties. As silica fume is introduced with slag simultaneously, the influence of slag specific surface is less important compared to the samples without silica fume.
Grzegorz MALATA Paweł PICHNIARCZYK
MODIFICATION OF GYPSUM PASTES WITH IZOSTRUCTURAL BARIUM AND STRONTIUM SULPHATES
The subject of the presented work is the influence of barium and strontium sulphate admixtures on gypsum paste’s properties. Admixtures were applied as an element of paste composition or as a water solution created with water and an admixture, applied to a hardened gypsum paste surface. The influence of the admixtures on mechanical properties, phase composition and microstructure of samples was examined. It was found that modification of the gypsum paste surface with strontium sulphate improves its waterproofness.
Jan MAŁOLEPSZY Łukasz KOŁODZIEJ
RESISTANCE OF CEM V CEMENTS TO CHLORIDE CORROSION
This paper presents the results of study into chloride penetration resistance of mortars containing composite cement CEM V and ordinary Portland cement (OPC) CEM I. The apparent diffusion coefficient for each mortars with different contents of mineral admixtures was determined using the concentration profile test after 2, 7, 28, 90, 400 days of diffusion. Strength of the mortars cured both in water and in 3% NaCl solution was investigated after 28, 90, 120 days. The microstructure and the phase composition of hardened cement paste after 28-day corrosion in 3% NaCl solution were also studied. For these purposes SEM and XRD analyses were used
Jan MAŁOLEPSZY Ewelina TKACZEWSKA
EFFECT OF FRACTION SIZE OF SILICEOUS FLY ASHES ON HYDRATION AND PROPERTIES OF CEMENT
The paper presents the effect of fraction size of siliceous fly ashes on hydration and properties of cement. Both fly ashes, below 16 m and from 16 to 32 µm, were analysed. The heat of hydration in cement pastes and a content of Ca(OH)2 in hardened mortars were examined. The setting time and compressive strength as well as microporosity and microstructure of cements were tested. The results showed that cement with fly ashes below 16 µm demonstrated higher heat of hydration, shorter setting time and higher compressive strength. The compressive strength of cement with finer fly ashes from the third hopper in an electrostatic precipitator system was higher than the one of Portland cement after 2 days. This difference rose to 30% after 180 days. It was observed that not only fineness, but also the structure of glassy phase and the ratio of glassy phase to crystalline phase decided about pozzolanic activity of fly ashes.
Jan MAŁOLEPSZY Wojciech WONS
INFLUENCE OF PHYSICAL AND CHEMICAL PROPERTIES OF FLY ASH FROM COAL ON SINTER ABILITY OF BUILDING CERAMIC PRODUCTS
Fly ash comes from mineral substances dispersed in a coal that are subject to many physical and chemical processes during coal combustion. Because of the high level of dispersion of mineral substances in a coal and the suddenness of thermal processes, the particles of fly ash are diversified as to their structure as well as phase and chemical composition. In the standard systems fly ash is separated from gases by a few sections of electrofilters placed in a row behind the combustion chamber. Ash from each of the section make up the separate raw material in the case of its application to the production of building ceramics. It turns out that the ashes caught closer to the combustion chamber can be used as a leaning addition in the production of porous ceramics and the ashes from the last section are precious raw material in the production of sintered ceramics.
STRENGTH DEVELOPMENT OF VIBROPRESSED CONCRETE
This paper presents the study on the development of compressive and splitting tensile strengths up to 28 days of vibropressed concretes (paving blocks), which were cured in two different conditions (standard laboratory condition and increased RH conditions). The aim is to determine a strength-time equation for these two conditions. Various strength-time equations taken from the literature are also given in the paper.
Paweł MURZYN Jerzy DYCZEK
RESEARCH OF THE INFLUENCE OF MELAPHYRE ADDITION ON PROPERTIES OF FIRED CERAMIC MATERIAL
The properties of the ceramic building materials strongly depend on the composition of the initial mixture of raw materials and the parameters of production process. The influence of melaphyre (from Rybnica Lesna) added to the clay raw material (kaoline Sedlec) at various amount and grain sizes on the properties of a fired ceramic material was investigated. The samples were fired at a temperature of 1220ºC. Two different sintering times, 5 and 30 minutes were used The heating speed was 8ºC/min. The fired materials were observed on SEM to characterize their microstructure. Porosity and flexural strength were also measured.
Miroslav BRODŇAN Katarína ŠLOPKOVÁ
CORROSION OF REINFORCEMENT IN REINFORCED CONCRETE BRIDGES
The paper presents the results of diagnostics of superstructures of bridges in use. The research of the influence of carbonatization of concrete on corrosion of reinforcement was carried out. The depth of carbonatization of concrete was determined in situ by a common and simple method, the phenolphtalein test. The actual state of the inbuilt reinforcement was tested in selected places of superstructures. Calculation of the duration of the passive state were made using the formulas of J.Bilčík.
INFLUENCE OF GRINDING METHOD ON QUALITY OF MINERAL AGGREGATES
Shape of grains of mineral aggregates affects the quality of affects the quality of concrete. Among various types of crushers, impact and cone crushers are those from which the highest content of regular grains is noticed. But after crushing in jaw crushers the largest amount of irregular grains is obtained. That unfavourable feature of jaw crusher can be partly reduced by using of jaws with specific type of grooving. In the conducted experiments the best results were obtained for the jaws with trapezoidal type of grooving (with a teeth height of 0,7 of grooving scale).
Lenka NEVŘIVOVÁ Karel LANG
MICROSTRUCTURE OF SILICA BRICK
Silica is a refractory which is significant from the chemical point of view for its high content of SiO2 (more than 93%). As a mineral, it is composed of various modifications of SiO2, particularly β-cristobalite and γ-tridymite. Further, it is composed of a low amount of unmodified β-quartz, calcium orthosilicates, and is in a vitreous state. Silica has a high bearing capacity in high temperature (up to 1700ºC). Its advantage is high resistance against acidic molten masses and the disadvantage is its low resistance against temperature changes to lower than 600ºC. The paper deals with descriptions of the microstructures of both dense (metallurgical, coking, glass) and thermal insulating silica.
Anna NIEWĘGŁOWSKA-MAZURKIEWICZ Tomasz PIOTROWSKI
MICROCRACKING AS A RESULT OF CONCRETE SUBSTRATE SURFACE TREATMENT
The aim of the study was an analysis of the surface treatment effect on formation of microcracks in the near-to-surface layer of a concrete substrate. The research was conducted with samples made of different types of concrete to which different treatment methods were applied. The optical microscope observation was used to evaluate cracks network characteristics. The quality of concrete substrates after the surface treatment was characterised by surface tensile strength determined by the pull-off method. The measurements of surface also carried out to establish a relationship between this property and surface tensile strength.
Wiesława NOCUŃ-WCZELIK Barbara TRYBALSKA
INTERACTION OF SOME ADMIXTURES ON THE KINETICS OF HYDRATION AND MICROSTRUCTURE OF CEMENT PASTE
The heat evolution kinetics on cement hydration with concrete admixtures was studied. Portland cements type CEM I and CEM II and silica fume additive were used. The heat measurements were carried out to find the acceleration/hindering effect as a function of hydrating mixture composition. The conductivity measurements were also carried out. The modification of the liquid phase conductivity in the presence of the additive and the admixtures was documented. This can be derived from different rate of cement phases hydrolysis as well as hindering of nucleation/crystallization of hydrates. The positive effect of admixture on the microstructure of hardened paste, particularly on C-S-H was also proved.
VERIFICATION OF STRENGTH MODELS OF FLY ASH CONCRETES
This paper presents strength models of fly ash concrete verification. Analyses were made on the basis of the research program carried out. Tests performed on 52 fly ash concretes with varied replacement of cement by fly ash from 0% to 50% and three types of fly ashes. The results show that only two from among eight verified models have good correlation coefficients (R ≥ 0,96). Thus, they may be useful for fly ash concrete designing.
Aneta NOWAK-MICHTA Maciej URBAN
INFLUENCE OF FLY ASH PROPERTIES ON RHEOLOGICAL PARAMETERS OF CONCRETE MIX
The article is a report from the research program carried out on 36 concrete mixes containing three fly ash types belonging to all three categories of unburned carbon content (A, B & C). The ashes have been added in doses ranging from 0 to 50% of cement replacement with different water-binder ratios. The investigations have been focused on rheological parameters. The test results show that the most important factor influencing workability of fly ash concrete mixtures is the unburned carbon content. Additionally research has proved that other factors affecting rheological parameters of these mixtures have been a water/binder ratio and a superplasticizer content.
Jiří BROŽOVSKÝ Tomáš FOJTÍK
EXPERIENCE OF CONCRETE PAVING BLOCK TESTING ACCORDING TO HARMONIZED EN 1338
The new harmonized European Norm (ČSN EN 1338) has been valid in the Czech Republic since December 2004. This standard specifies the requirements concerning materials, properties and test methods for concrete paving blocks. The paper presents the differences in these requirements given in ČSN EN 1338 and the Czech standards formerly used.
THE EFFECT OF HEAT TREATMENT ON EXPANSION OF MORTAR IN A CONDITION OF INSIDE CORROSION
The paper presents the results of laboratory tests on heat treatment of mortars with reactive silica aggregate and cement of varied alkali content. Linear change of the analysed samples was tested and the microstructure was observed by means of scanning microscopy and X-ray microanalysis. The mortars displayed excessive elongation after several months. The mortars were found to contain both sodium-potassium-calcium silicate and large amounts of ettringite located in the contact zone between the aggregate and the paste as well as in air voids. The occurring ettringite has been generated from the components from the mortar pore solution, without sulphate ions supply from the environment.
Marek PETRI Grzegorz SAWICKI
IMPACT RESISTANCE OF HYBRID FIBRE REINFORCED MORTARS
The impact resistance made of cement mortars reinforced with was determined. The following fibres were used: three types of polypropylene fibres, one type of steel fibres, one type of glass fibres and theirs mixtures. The fibres were different in mechanical properties, size and shape. The impact resistance test were conducted according to the procedure described in the ACI Committee 544 Rapport „Drop-Weight Test”. It was found that the addition of fibres improved the impact resistance proportional to their content in mortar. The best result was observed in hybrid fibres case.
Tomasz PIOTROWSKI Anna NIEWĘGŁOWSKA-MAZURKIEWICZ
EFFECT OF SURFACE TREATMENT ON BOND STRENGTH IN REPAIR SYSTEMS
Bond strength between a concrete substrate and a repair material is of great importance in the field of repairs and strengthening of structures. Surface treatment before application of a new layer has been presented in the guidelines for years and is intuitively defined as one of the major factors on repair durability. Therefore the choice of proper surface treatment method is significant. In this paper the effect of different surface treatment methods on bond strength was analysed. Repair systems were differentiated by: class of substrate concrete, repair layer thickness, type of repair material, use of primer.
INFLUENCE OF CONTENT AND GRANULATION OF CHALACEDONITE SLUDGE ON QUALITY OF SAND-LIME BRICKS
Sand-lime bricks are conventionally manufactured from natural quartz sand and burned lime. Bricks produced in Polish can be classified into 20 or 25 class. This parameter can be improved considerably by introduction of an additional component, waste chalcedonite sludge, into a raw material mixture. The waste material is obtained during exploitation of chalcedonite from „Teofilów” deposit and is mainly composed of amorphous form of silica and a minor admixture of clay minerals. Because of its mineral composition, chalcedonite sludge can be used in sand-lime bricks production as an active mineral addition reacting effectively during the chemical reactions in the hydrothermal conditions to form the final products of synthesis. Chalcedonite sludge can also be used as a micro-filler, that is especially important during brick’s formation. As the result of synergistic effect of waste chalcedonite sludge, sand-lime bricks are characterized by higher compressive strength, which was confirmed by the laboratory study.
PROPERTIES OF CERAMIC MATERIALS OBTAINED WITH ADDITION OF FOUNDRY SCRAP MATERIALS
The paper contains the results of a study on the influence of waste mould and core sands formed in the foundry industry on the usable properties of ceramic building materials. The mentioned waste sands can substitute natural quartz sand. Sand is used as a leaning additive in traditional clay based ceramic building materials. Usefulness of waste mould and core sands as components of plastic bodies was evaluated based on the fundamental usable properties and the microstructure of ceramic materials. The studies were carried out according to Polish standard PN-EN 771-1:2005. The positive results of the research confirm that waste mould and core sands can be used after proper treatment as a leaning additive in the plastic bodies used for forming ceramic building materials.
Pavel ROVNANÍK Patrik BAYER
THE SIZE EFFECT OF AGGREGATE ON THE PORPERTIES OF ALKALI ACTIVATED SLAG COMPOSITE EXPOSED TO HIGH TEMPERATURES
Concretes based on alkali activated slag exhibit higher resistance against high temperatures than concretes made from Portland cement. In order to take advantage of this binder, the utilization of heat-resistant aggregates, such as electrical porcelain, is desirable. We have examined the influence of aggregate size on the behaviour of the composite during heat loading to 1200ºC and the mechanical properties after high temperature exposure. The microstructure was investigated by using mercury intrusion porosimetry and scanning electron microscopy.
Zbigniew RUSIN Grzegorz STELMASZCZYK Łucja NOWAK Przemysław ŚWIERCZ
INFLUENCE OF BLAST FURNACE SLAG ADDED TO PORTLAND CEMENT ON WATER FREEZING PROCESS IN MORTARS
The paper presents the results of the research on pore size distribution and on freezing water process in the mortars with Portland cement, blast furnace slag cement, and with different water/cement ratios (0,30; 0,37 and 0,45). The freezing water process was estimated with the RAO technique. Mercury Intrusion Porosimetry (MIP) was used to determine the pore size distribution in the mortars.
BUILDING ENERGY INTENSITY FOCUSED ON BUILDING MATERIALS
Structures are connected with energy resources consumption during the stages of their build-up processes, utilisation and liquidation. Whole life-cycle of the structures can make up the significant benefit for energy demand reduction, with the aim to assure the sustainable development principles. Building material can be characterized by the amount of energy utilized for its production. In respect of the ecological importance, the amount of this energy (as well as emissions accompanying) can belong among the basic criteria for the buildings impact on environment evaluation. The resources for definition and finding the energy intensity of building materials production and some acquired results are to be described in the paper.
Jiří BROŽOVSKÝ Aleš KRATOCHVÍL Petr MARTINEC
FROST RESISTANCE OF CONCRETE MADE WITH GYPSUM FREE CEMENT
Durability belongs to the most important concrete parameters. In case of cement-concrete wearing courses of roadways, we are speaking about concrete surface resistance to impact of frost and thawing alternation and to impact of applied defrosting chemicals. Owing to newly built cement-concrete roadway wearing courses, this parameter has been detected on 28th day after the concreting. For subsequent repairs, however, we cannot eliminate a situation, in which the built in concrete showing the strength parameters typical for the age of 1 or 3 days will be exposed to frost and to impact of defrosting chemicals during a period of less than 28 days. In repairs of cement-concrete wearing courses, concretes using gypsum free cements and representing the high performance types also are applicable.
Lenka SMETANOVÁ Radomír SOKOLÁŘ
POROUS CERAMIC TILES FROM FLY ASH
The paper has the task to evaluate and propose the possibility of dry pressed ceramic tiles production by exclusive use of raw mixture based on fly ash. The water glass for increase of green and firing fly ash body strength was used. It was judged properties of the firing fly ash bodies according EN ISO 10545 standards (e.g. water absorption, bending strength) and properties of the fly ash body microstructure. For example by using of milled fly ash with 10% mass water glass content and firing temperature at 1100ºC it was achieved of frost resistant fly ash firing body which correspond to the strict requirements for ceramic tiles of group BIIa according to EN 14411 (water absorption 3,4% - maximal limit 6%, bending strength 30,2 MPa - minimal limit 22 MPa). The same firing fly ash body without content of water glass had water absorption 19,1% and bending strength only 10,3 MPa.
WASTE MATERIALS FOR THE PRODUCTION OF DRY PRESSED CERAMIC TILES
In the traditional technology of dry pressed ceramic tile production uses only natural raw materials (clays, feldspars, quartz etc.). In the Czech Republic, the annual production of wall and floor tiles amounted to more than 30 million square meters in the year 2005; raw materials mining for such a quantity results in significant damages to the landscape. The aim of the conducted works presented in this paper is to investigate the possibility of the application of waste materials using for the production of dry pressed ceramic tiles. By using power plant fly ashes or several quarry dusts and firing of the raw material mixtures at 1100-1200ºC, it was possible to prepare a ceramic body with properties which correspond to those of dry pressed ceramic tiles manufactured from pure natural raw materials (mostly alumino-silicates) according to EN 14411 standard. This paper describes the properties (e.g. water absorption, bending strength, bulk density) of the fired fly ash and mixed fly ash - hornblende dust bodies tested according to ISO 10545 and microstructure of the firing fly ash body (for example pore structure measured by the high pressure mercury porosimetry method to predict the frost resistance).
DEVELOPMENT OF THE MOULDS IN CEMENT MATERIALS AND THEIR INFLUENCE ON MORTARS PROPERTIES
This study shows the results of influences of various species moulds (Penicillium chrysogenum and Cladosporium herbarum) on the properties of cement mortars and polymer modified cement mortars. Influence of two different medium such as medium MEA and gypsum-carton board research. Especially, results of carry research point at high mould contamination cement mortars modified polymer. However, intensity of development of moulds, it doesn't depend on kind of medium practically. Growth of fungi affect on flexural strength as well as sorptivity coefficient of cement mortars.
Janusz SZWABOWSKI Beata ŁAŹNIEWSKA
FROST RESISTANCE AND POROSITY STRUCTURE OF SELF COMPACTING CONCRETE (SCC)
Based on the actual state of knowledge and in accordance with PN-EN 206-1:2003 norm, using air entrainment is recommended as a basic way for obtaining the frost-resistance of concrete. Moreover, concrete will be frost resistant if the value of the porosity structure parameter is included in a precise set of limits. The research was conducted to verify whether the self-consolidation process affects an air-void stability. Concrete resistance to freezing and thawing after 300 cycles according to PN-88/B-06250 and parameter of porosity structure according to PN-EN 480-11 were tested. The results of the investigations showed that the parameters of porosity structure were not included in a precise set of limits for the analysed self-compacting concretes. The issues connected with this problem are the subject of this paper.
Janusz SZWABOWSKI Tomasz PONIKIEWSKI
WORKABILITY AND STRENGTH OF STEEL FIBRE SELF-COMPACTING CONCRETES
The methodology and the results of the investigation on the influence of steel fibres on rheological and mechanical properties of Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC) are presented and discussed in the paper. The rheological parameters of SFRSCC (that behaves as a Bingham body) - yield value g and plastic viscosity h were determined by using a new type of rheometer BT2 in mortar and concrete mix research. The mechanical parameter of SFRSCC - the cube compressive strength was tested as well. The experimental verification of the influence of volume content of fibres, fibre factor, length and shape of fibres on the rheological properties of SFRSCC was investigated. The results obtained for mixes with three types of steel fibre shapes are presented in the paper. The length of fibres do not have the significant influence on yield value g and plastic viscosity h of SFRSCC. The significant effect of the length of fibres on plastic viscosity h was only observed in the case of SFRSCC with hooked steel fibres.
Ivailo TERZIJSKI Zbyněk KERŠNER Jan VÍTEK
MODEL OF PEDESTRIAN BRIDGE UTILIZING UHPC
Present technology is able to produce a concrete of a characteristic strength of 100 MPa without significant problems. Moreover, in a few past years a new grade of high strength concrete was developed - UHPC, it means Ultra High Performance Concrete. For the UHPC is typical compressive strength of 150 MPa and above, and tensile strength of 20 MPa and above. These properties are allowed due to special composition of the concrete containing dispersed metallic fibres. Presented paper informs about possible usage of UHPC in a tied arch shell structure. For this task the model of mentioned structure was cast from special UHPC concrete mix. The paper deals with basic properties of the concrete and with the manufacturing and testing of the model.
THE INFLUENCE OF FLY ASH QUANTITY AND PROPERTIES ON SELF-COMPACTION OF CONCRETE MIX
Contemporary in Poland, fly ash is the most common addition used in concrete. In self-compacting concrete (SCC) using quite high dosages of mineral additions is often necessary to decrease the cement content to avoid coarse aggregate sedimentation. Taking all of these into account, the research program has been conducted. The investigations have been focused on maximum possible dosage of three types of fly ash to maintain self-compacting properties of concrete mix.
Sławomir CHŁĄDZYŃSKI Paweł PICHNIARCZYK
ESTIMATION OF PROPERTIES OF GYPSUM PLASTERS ACCORDING TO POLISH AND EUROPEAN STANDARDS
The state of novelization of Polish gypsum standards, especially for gypsum plasters, has been discussed in the paper. The results of comparative investigations of gypsum plasters tested using national and European methods have been presented and discussed. The principal differences with respect to methodology of investigations, standard requirements and interpretation of obtained results have been pointed out.
Alexandr V. USHEROV-MARSHAK Victor SOPOV Benedykt KARCZEWSKI
CALORIMETRIC INVESTIGATIONS ON INFLUENCE OF SILICA FUME AND METAKOLINITE ON EARLY AGE CEMENT HYDRATION
In present paper the results of investigations on influence of metakaolinite and silica fume on early age hydration of cements are presented. Two cements were used in experiments: CEM I 42,5 R and CEM III /A 42,5 N HSR/NA. The amounts of additives introduced to the binders were between 5 and 20% by mass in respect to cement mass. Moreover, in case of binders containing metakaolinite SNF type superplasticizer was used. Microcalorimetry has been chosen as a method which enables to characterize kinetics of early stages of hydration. The results showed that in case of CEM I cement both silica fume and metakaolinite addition diminish the thermal effect during first 24 hours. The intensity is proportional to the amount of additive introduced. For CEM III/A based binders there was no proportional relationship found. In case of both cement types, total heat of hydration within 24 hours for binders containing additives was lower comparing to cements without additives.
Dominik GAZDIČ Jan NOVÁK
CALCIUM SULPHATE BASED BINDER DEVELOPMENT OF NATURAL ANHYDRITE
Until recently the sulphate binder based on anhydrite was not utilized in our building industry. The main reason is the fact that on the territory of the Czech Republic doesn´t occur the necessary raw material source. In spite of that the anhydrite binder is a building material of quality in the building industry, especially in the manufacture of dry mortar mixtures. The optimization question of natural anhydrite hardening acceleration was solved in the framework of the work and further the effects of external parameters on the next development of self-leveling anhydrite coats., i.e. the effects of modifying admixtures such as liquefying and antifoaming agents and eventually of disperse admixtures.
Ludmila VEHOVSKÁ Karel KALIVODA
UTALIZATION OF FBC ASH IN PRODUCTION OF BLENDED CEMENT
Our department has been working on the issue of using FBC ashes for a blended cement production – as part of a grant-financed project. The FBC ashes have a higher content of SO3, a higher content of highly reactive CaO and sometimes also a higher loss on ignition. The content of these substances is the reason for volume and thermal instability. In spite of that it is possible to admit that the FBC ash can be added in a certain limited concentration into a binder of related chemical and mineralogical composition i.e. into Portland cement.
DURABILITY OF BINDERS CONTAINING DIFFERENT AMOUNTS OF GRANULATED BLAST FURNACE SLAG
Based on the results of long-term durability tests the author analysed the influence of the granulated blast furnace slag addition on the phase composition and microstructure of the hydrated binder pastes.
The results confirmed that the increase in slag addition to the binder leads to the significant changes of the C-S-H phase parameters, the amount and composition of hydrogarnets as well as to the reduction of portlandite content. Such situation significantly modified the durability of the pastes in MgSO4 and chloride solutions. The author analysed the relationships between C/S and C/A factors of the binders and their corrosion resistance.
SIZE EFFECT IN COMPRESSIVE STRENGTH TESTS OF SPECIMENS DRILLED OUT FROM LIGHTWEIGHT CONCRETE WITH SINTERED FLY ASH AGGREGATE
The problem of size effect of specimens drilled out from lightweight concrete with sintered fly ash aggregate is presented in this paper. The effect was analysed taking into consideration the influence of shape (slenderness) and size of cores cut out from blocks made of two different lightweight concretes of various strength and density levels. It was revealed that in the case of researched structural lightweight concretes the size effect of cores in compressive strength tests is less important in comparison with normal weight concrete.
MODULUS OF ELASTICITY OF LIGHTWEIGHT AGGREGATE CONCRETE MODIFIED WITH STEEL FIBRES
This paper deals with the influence of steel fibre additive on the modulus of elasticity of lightweight aggregate concrete. Variability of concrete strength and density as well as fibres content were taken into consideration in research programme carried out. The analysis of obtained results confirmed the fact about a lower modulus of elasticity for lightweight concrete than that for normal weight one of the same strength class. Moreover, it was also revealed that, contrary to some literature reports, there was no effect of the fibre additive on the modulus of elasticity in the investigated range.
Lucyna DOMAGAŁA Maciej URBAN
RHEOLOGY OF LIGHTWEIGHT AGGREGATE CONCRETE WITH STEEL FIBRES
Structural lightweight aggregate concrete (LAC), in spite of its numerous advantages, is characterised by lower mechanical parameters in comparison with normal weight one of the same strength class. Modification of LAC compositions with steel fibres makes it possible to enhance some of mechanical characteristics. Nevertheless, it may also cause deterioration of rheological parameters. In this paper the results of rheological tests on LAC mixture reinforced with steel fibres are presented, taking into consideration various levels of LAC strength and density.
Rostislav DROCHYTKA Božena VACENOVSKÁ
NEW PROGRESSIVE ELEMENTS IN MANUFACTURE OF ARTIFICIAL AGGREGATE OF SINTERED ASH
This work is aimed at some new progressive elements in manufacturing artificial aggregate of sintered ash, which can resolve its earlier economic problems. One of this new element’s possibilities is using fluidic ash as a raw material for manufacturing artificial aggregate of sintered ash and another is predrying of crude charge by preheated waste gases, which will provide maximum utilization of energy.
Tibor ĎURICA Melinda SASÁKOVÁ
DURABILITY OF THE COATING SYSTEM
The durability coating system applied for protection of concrete tunnel linings is presented in the paper. The pull-off test carried out after the application of the coating system to concrete and after the tests to chemical resistance (resistance to four aggressive chemicals), frost resistance and Wetting-Drying. The assessment of the state of the coating system surface after the performed tests and permeability test results are given in the paper.
Kazimierz FLAGA Maria BOGACKA Przemysław MALISZKIEWICZ
DURABILITY FEATURES OF BRIDGES CONCRETES ILLUSTRATED ON THE BASIS OF HIGHWAY BRIDGES STRUCTURES - HIGHWAY A2, SECTION KONIN-KOŁO-DĄBIE
There are results of wide range concerts laboratory tests presented in the paper. Tests have been done on concretes that were used to build 48 bridge structures on highway A2, section Konin Koło Dąbie. Having at disposal about one thousand of tests determination results it was made the statistic analysis. The analysis has proved that (with exception of compressive strength R28, water permeability hw - correspond to W8 waterproof degree) raised difficulties with concrete durability requirements, such us: freeze resistance - ΔRz and absorbability nw. Received correlation relationships pointed essentially influence of compressive strength R28 and absorbability nw on freeze resistance ΔRz. The influence of air entrainment of concrete, micro silica additives and concrete structure density on observed in tests relationships was also analysed.
Marcela FRIDRICHOVÁ Petra POSPÍŠILOVÁ
DEVELOPMENT OF BARITE SHIELDING SYSTEM
Special building materials are used for protection of walls in rooms with X-rays or therapeutic equipment (e.g. betatrons, linear accelerators and other working places utilizing ionizing radiation). The research on the „Compact Building Materials System Protecting against Harmful Ionizing Radiation” was carried out within the program „Pokrok” (=„Progress”). The results of the tests on the properties of various barite-based materials are presented in the paper.
Marek GAWLICKI Wojciech WONS
APPLICATION OF FBC FLUIDIZED BED COMBUSTION FLY ASH AND CONVENTIONAL BOTTOM SLAG TO THE PRODUCTION OF FLY ASH CONCRETES FOR ROAD BUILDING
New types of energy wastes have been generated after installation of fluidized bed boilers in many power plants and thermal power stations. These wastes can be used in road building. The analysis of the mixtures consisted of small amounts of Portland cement (5-7%), fly ash from fluidized bed boilers and furnace slag from conventional boiler pointed out that these mixtures, after setting and hardening process, can be treated as fly ash concretes. Fly ash and cement included in these concretes are a binding material and a supplement of fine aggregate fractions. At an early phase of fly ash concrete hardening, ettringite is very important.
Zbigniew GIERGICZNY Artur GOLDA
CONCRETE WITH FLY ASH AND RECYCLED AGGREGATES
The paper presents the influence of fly ash addition on the properties of concrete containing varying amount (from 10 to 50%) of recycled aggregates in its composition. The positive influence of fly ash addition on the consistency of concrete mixture as well as on the properties of hardened concrete (absorbability, standard strength, frost resistance) has also been stated.
Michał A. GLINICKI Marek ZIELIŃSKI
MICROSTRUCTURE OF AIR VOIDS IN CONCRETE CONTAINING FLUIDIZED BED FLY ASH
The experimental investigation on microstructure of air voids in air-entrained concrete, modified with an addition of fly ash from fluidized bed combustion of coal, is presented. The additive was used for partial replacement of cement up to 40%. Tests of air content in concrete mix revealed a proportional increase of the dosage of air entraining admixture, needed to achieve the target air content of 6±1%, along with increasing content of fluidized bed fly ash. The distribution of air voids in concrete was evaluated using a digital method of image analysis on polished sections. The influence of addition of fluidized bed combustion fly ash on the spacing factor and on the specific surface of voids is discussed.
INFLUENCE OF CEMENT PROPERTIES ON RHEOLOGY OF FRESH SUPERPLASTICIZED MORTARS
The results of research into the influence of cements with various in physicochemical properties on rheology of fresh mortars containing PC and PE superplasticizers are presented. Rheology results have been evaluated according to the Bingham model, which describes the rheology with the two parameters: yield value and plastic viscosity. The basic trends of influence of specific surface of cement and C3A, Na2Oeq, SO3 content in cement on rheology of mortars with different superplasticizers are presented and discussed. On the basis of the obtained results, a regression model of the influence of cement specific surface and C3A, Na2Oeq, SO3 content in cement on rheological parameters of mortars was developed.
INFLUENCE OF TYPE AND AMOUNT OF POLYMER ADDITIVE ONTO THE SHRINKAGE OF CEMENT MORTARS AND CONCRETES
The influence of different types of polymer additive onto the shrinkage and mechanical properties of cement composites is presented in the paper. This influence is compared to the effect of the shrinkage reducing organic admixture that is widely applied at present. The results of the conducted research state that the significant reduction of shrinkage strains and the increase in bending strength can be achieved after using polymer dispersion additive at the amount of at least 5% of the mass of cement. Shrinkage reduction and improvement of service properties determine to a large extent the technical attractiveness of polymer-cement materials for concrete structure repairs and for constructing industrial jointless primers and floors.
Wioletta GRZMIL Jerzy WAWRZEŃCZYK
INFLUENCE OF CARBONATION ON FREEZE-THAW RESISTANCE OF CONCRETE WITH GBFS CEMENT
The paper presents the results of preliminary tests, which aim at determining the influence of accelerated carbonation and other factors linked to the composition of cement (water/binder ratio and percentage of GBFS) on the fundamental properties of concrete (compressive strength, water absorption) and surface scaling resistance.
ABRASION WEAR OF HIGH PERFORMANCE CONCRETE IN HYDRAULIC STRUCTURES
This paper presents a mathematical model for kinetics of abrasive wear of concrete in hydraulic structures. The underwater method ASTM C1138 was used to test abrasive wear of concrete in hydraulic structures. The paper includes the results for high performance concrete (HPC) and a description of water/cement ratio (w/c) influence on abrasive wear of HPC under constant load. The formulated mathematical model of concrete wear matched the test results quite well.
Adam HUBÁČEK Rudolf HELA
PROPERTIES OF SELF COMPACTING CONCRETES WITH DISPERSED REINFORCEMENT
The research on the properties of self compacting concrete (SCC) with various types of fibres was carried out. Four types of fibres steel, polypropylene, glass and polyolephine fibres, were used as a fibrous reinforcement of SCC. The results of the investigations into the rheological and mechanical (compressive and tensile strength, shrinkage, static and dynamic modulus of elasticity) properties of SCC are presented in the paper.
Tomasz JUSZCZAK Jerzy WAWRZEŃCZYK
RELATIONSHIP BETWEEN WATER AND CHLORIDE ION PERMEABILITY OF HARDENED CONCRETE AND AIR CONTENT IN CONCRETE MIX
The paper presents the results of laboratory study to evaluate the influence of air content in concrete mix and type of cement (Portland cement and slag cements) on water and chloride permeability of concrete. The experimental works were conducted on 29 concretes that were different in water-binder ratio (W/B=0,35-0,50), air content in concrete mix (1,3-13,5%) and the amount of ground blast furnace slag in cement (CEM I, CEM II/A-S, CEM II/B-S, CEM III/A).
Veronika KALOVÁ Božena VACENOVSKÁ
NEW LIGHTWEIGHT ARTIFICIAL AGGREGATE OF SINTERED FLY ASH
In Czech Republic the classical fly ash is used for processing of concrete, mortar, cement and bricks. The using of fly ash for processing of artificial aggregate was ended a few years ago. The reason for this was obsolete and economically ineffective technology of processing. The most major negative economic effects were these three; high consumption of natural gas which is used for ignition of raw material charge, high costs for the purchase of coal and its treatment by wet milling and very high investment costs. Nevertheless, the produced aggregate were used for production of high quality light-concrete and also common concrete in great range. All these factors helps in generating renewed interest in innovating the technology of production sintered fly ash aggregate in Czech Republic. The most important innovating items for production of sintered fly ash aggregate are reduction of natural gas consumption and the use of fluidized fly ash as a basic raw material.
Zbyněk KERŠNER Pavla ROVNANÍKOVÁ Vojtěch BAŠTA
APPLICATION OF FLY ASH AND ASH FROM BIOMASS COMBUSTION AS POZZOLANIC ADDITIONS IN LIME MORTARS
After combustion of biomass, such as cereal straw or coniferous wood sawdust and bark, fly ash and ash remain as waste materials. Vegetable ashes contain a certain amount of amorphous silicon dioxide. These ashes have pozzolanic properties and are able to react with calcium hydroxide at ordinary temperatures. Compounds like C-S-H gels are formed during the reaction. The mechanical properties of mortar specimens prepared from lime, sand and fly ash from coniferous wood sawdust are presented in the paper.
Filip KHESTL Jiří BYDŽOVSKÝ
HEMP BASED CEMENT-BONDED PARTICLEBOARDS
This paper deals with possibilities of partial supplying of primary components in original prescription of wood-cement boards by secondary raw materials. That will achieve a decrease in production loads, modification of building board characteristics and, last but not least, a decrease in ecological damage. Unfortunately, not every fast renewable or secondary raw material could be used as filler in cement bonded building materials. Alternate aggregates must not noticeably affect adversely with cement or any other used component at hydration. One of the potential alternatives is hemp.
Zbigniew KLEDYŃSKI Agnieszka MACHOWSKA
MECHANICAL AND HYDRAULIC PROPERTIES OF HARDENING SLURRIES MADE FROM SLAG BINDER ACTIVATED BY FLUIDAL FLY ASH FROM LIGNITE COMBUSTION
Development of technology of sheet pile walls and cut-off walls and also changing standards of environmental protection concerning utilisation of combustion products result in searching new materials for hardening slurries. The results of strength and hydraulic conductivity tests of an original material, i.e. high-water slurry of bentonite and a binder, ground granulated blast furnace slag, activated by an atypical activator, fluidal fly ash from lignite combustion, are presented in this paper. The analysis of the obtained results proved that the material presented satisfactory strength and hydraulic conductivity for utilisation in construction of cut-off walls.
Karel KOLÁŘ Tomáš KLEČKA Jiří KOLÍSKO
INFLUENCE OF POLYCARBOXYLETER SUPERPLASTICIZERS AND MICROFILLERS ON THE MODULUS OF ELASTICITY OF HPC
The influence of various types of micro-fillers in combination with superplasticizer on the properties of High Performance Concrete (HPC) was tested. A comparative study on the effect of various mixture compositions on the workability, the compressive strength and the static modulus of elasticity in compression of HPC is presented in this contribution. The obtained results are a part of experimental works conducted at laboratories of Klokner Institute of Czech Technical University (CTU) in Prague and the Faculty of Civil Engineering at CTU in Prague.
Marta KOŘENSKÁ Zdeněk CHOBOLA Radomír SOKOLÁŘ Iveta PLŠKOVÁ Jan MARTINEK
FREQUENCY INSPECTION AS AN ASSESSMENT TOOL FOR THE RESISTANCE OF CERAMIC TILES
The frequency inspection method is based on the physics of elastic stress wave propagation in bodies. An exciting impulse, being realized, for example, by a mechanical impact on the specimen surface, gives rise to low-frequency stress waves to propagate within the structure and reflect on cracks and the specimen surface. The specimen response to the exciting impulse is picked up on the surface by means of a sensor and transmitted to a computer for frequency analysis. The predominant frequencies may be associated with multiple reflections within the structure, carrying information on the structure integrity and defect localization. The present paper deals with an experimental study of the frequency inspection method applicability to assess the long frost resistance of ceramic tiles. In order to verify the frequency inspection results and examine their application to the ceramic tile frost resistance assessment, we have also analysed some of the tiles' other properties, such as, porosity and following its microstructure.