Lech Czarnecki, Izabela Hager, Tomasz Tracz
Material Problems in Civil Engineering: Ideas-Driving Forces-Research Arena
The paper presents the evolution of the MATBUD conference and discusses the driving forces of research in the field of building materials. The paper attempts to interpret the trends in relation to the development of building material engineering. The approach adopted here is the investigation of the relation between material model and performance model as well as main drivers of building material research: idea, performance, research tools development, application and technological evolution.
Grigory Yakovlev, Irina Polyanskikh, Galina Fedorova, Anastasiia Gordina, Aleksandr Buryanov
Anhydrite and Gypsum Compositions Modified with Ultrafine Man-Made Admixtures
The influence of technogenic ultrafine additives on structure and properties of binders based on calcium sulfate has been studied. The study of physical and mechanical properties of gypsum compositions modified with metallurgical dust has showed an increase in ultimate compressive strength up to 30%, ultimate bending strength – 15%, the value of water resistance of the binder did not change. 1% of metallurgical dust being added to natural anhydrite, there is a significant increase of the strength of the composition by 40%, and the water resistance of the material decreases slightly. The conducted X-ray analysis does not show the presence of any new products of hydration and intensification of hydration of calcium sulfate dehydrate. At the same time, the conducted studies of the structure of the compositions confirm significant changes in the morphology of new formations. Thus, adding ultrafine additives to natural anhydrite and gypsum leads to the formation of a dense matrix of the increased strength.
Grzegorz Mazurek, Karol Nowakowski
The Evaluation of SMA Mixture Properties with the Surface-active Agent in WMA Technology
This paper presents the results from the study of the influence of the amount of surfactant (THPP) on selected properties of a stone mastic asphalt mixture (SMA) produced in Warm Mix Asphalt technology. The dosage of the adhesive agent was 0% (reference value), 0.2%, 0.4% and 0.6%. In addition, the experiment was extended to cover temperatures 110 °C, 120 °C, 130 °C and 140 °C. The study was carried out according to the experimental design 42. The design of the experiment involved preparing series of samples tested to determine the stiffness modulus (Sm) at temperatures 0 °C, 10 °C and 20 °C as well as the void content (Vm). The paper also discusses the influence of surface-active agents on bitumen parameters. The results from the tests indicate that the use of the THPP modifier may significantly affect the properties of the SMA mixture. The presence of the surfactant is a factor in reducing the SMA mixture compaction temperature by about 20 °C relative to the reference SMA temperature. With respect to bitumen parameters, the impact of THPP was marginal.
Wojciech Kubissa, Roman Jaskulski, Artur Koper, Jacek Szpetulski
Properties of Concretes with Natural Aggregate Improved by RCA Addition
We can observe the growing tendency of usage of recycled concrete aggregate (RCA). Changes in waste materials management rules will result in necessity of more common reutilization of materials from demolished concrete structures. Thus new fields of RCA application and new ways of its utilization in concrete manufacturing are still being looked for.
Research presented in the paper has been conducted to examine two methods of improving poor gradation of natural aggregate (NA) using RCA. The NA that did not fulfill requirements of gradation had been chosen. It consisted of ca. 75% of 2-4 mm fraction. In the first method a part of NA was replaced with 2-16 fraction of RCA of low quality. In the second method also a part of NA was replaced this time with 4-8 mm and 8-16 mm fractions of good quality RCA. The amount of replacing fractions was precisely calculated in order to fit optimal gradation curve. Quality of the gradation was measured with so called gradation index. Mechanical properties of researched concretes was tested as well as some of their properties related to durability. It can be stated, on the basis of the results, that both methods improve most of the vital concrete properties.
Elżbieta Horszczaruk, Paweł Sikora, Paweł Zaporowski
Mechanical Properties of Shielding Concrete with Magnetite Aggregate Subjected to High Temperature
This paper presents an experimental study on the performance of shielding concrete with magnetite aggregate subjected to high temperature. Two concretes with magnetite aggregate and one ordinary concrete with natural aggregate were tested. Mechanical properties were studied at ambient temperature and after thermal exposure. Compressive strength and splitting tensile strength have been tested. For each test, the specimens were heated at a rate of 1 °C/min up to different temperatures (300, 450, 600 and 800 °C). In order to ensure a uniform temperature throughout the specimen, the temperature was held constant at the target temperature for 1 h before cooling. In addition, the specimen mass was measured before and after heating in order to determine the weight loss of tested samples. Studies have shown that use of magnetite aggregate can diminish the negative impact of elevated temperatures on mechanical properties of concretes.
Paweł Łukowski, Ali Salih
Durability of Mortars Containing Ground Granulated Blast-furnace Slag in Acid and Sulphate Environment
The paper deals with corrosion resistance of cement mortars with various amounts of ground granulated blast-furnace slag (GGBS). The mortars were tested in the environment containing acids and sulphates corresponding to the aggressive factors acting on concrete in agricultural areas. The strength development of the composites with GGBS is slower; however, the losses in their strength and mass, as well as linear changes, after storing in the aggressive environment, are lesser than for those containing only Portland cement. This can be attributed, most likely, to the favourable changes in the hardened paste microstructure, caused by GGBS presence. The addition makes the structure of the hardened cement paste more compacted, diminishing the porosity and improving the tightness The long-term tests confirm that cement composites containing GGBS can be rational substitutes for ordinary cement concrete in the aforementioned field. However, the subject of the presented research were mortars; the conclusion shall be verified by concrete testing, planned as the next step of the project.
Wojciech Piasta, Julia Marczewska, Monika Jaworska
Durability of Air Entrained Cement Mortars Under Combined Sulphate and Freeze-thaw Attack
The paper deals with experimental results of combined sulphate expansion and freeze-thaw attack on air entrained (AE) and non-air entrained (nAE) ordinary portland cement mortars. After prior freezing and thawing of the 4x4x16 cm mortar bars the part of them was subjected to sulphate attackof the 5% Na2SO4 solution. Another part of mortar bars was immersed in the sulphate solution for 110 days and then these bars were frozen and thawed. The resistance of nAE and AE mortars to regular sulphate and freeze-thaw attacks alone was tested as well. In order to compare damage degree of mortars in all environments, there were investigated long term linear strains (expansion), and compressive strength of mortars. Also the SEM and XRD analyses of mortars were carried out. Compared to the individual sulphate attack alone, prior freeze-thaw and following it sulphate attack affected significant acceleration of sulphate expansion of nAE and AE mortars as well, despite much better resistance of AE mortars to freezing and thawing. However, the prior sulphate attack significantly reduced AE mortars resistance to freezing and thawing. The SEM analysis showed that air voids in AE mortars were partially filled with ettringite. Its precipitation in air voids of AE mortars caused that the volume of air was diminished and freeze-thaw resistance of AE mortars was significantly decreased and it was as low as resistance of nAE mortars was. The complete destruction of AE mortars subjected to sulphate attack alone occurred earlier than that of nAE mortars did. Based on SEM analysis results it is suggested that lower sulphate resistance of AE mortars was due to higher porosity of the air void-paste interface and its higher initial w/c ratio compared to ‘bulk paste’ farther away from.
Jacek Kubissa, Marcin Koper, Włodzimierz Koper, Wojciech Kubissa, Artur Koper
Water Demand of Concrete Recycled Aggregates
The procedure of designing the composition of concrete with the method of three equations demands to accept the assumptions regarding the consistence of concrete mixture. For the assumed consistency the water demand of aggregates and water demand of concrete is specified. In case of natural aggregates (NCA) the formulas, among others, of Sterne's of Bolomey's are used conditioning the water demand of aggregates from its granulation, kind and consistence of concrete mixture. There is lack of such dependencies in case of water demand of recycled aggregates (RCA). In such case there remains the empirical determination of the water demand, which in practice disqualifies the usefulness of the method of three equations to specify the concrete composition of on RCA aggregates. A way to solve this problem is looking for the relations between RCA water demand and its other qualities which are easy to specify in laboratory conditions in short time. The quality which gives such a chance to achieve this relation is the aggregates resistance to crushing whose measure is crushing indicator. This paper has made an attempt at specifying the manner of empirical definition of RCA water demand.
Nocuń-Wczelik Wiesława, Trybalska Barbara, Dziub Sylwia
The Properties of Cement Pastes and Mortars Processed with Some Heavy Metal Nitrates Containing Solutions
The effect of some heavy metal nitrates on the course of early hydration process and the properties of hardened cement mortars was investigated. Heavy metal compounds were introduced to the hydrating cement composites in soluble form of nitrates. The results of tests allow to make a comprehensive assessment of the impact of lead, cadmium and nickel nitrate added in amounts of 1% to 5% by weight of cement. The calorimetric measurements together with conductometric, shrinkage, compressive strength measurements and microscopic observations were carried out. These salts modify the rate of cement hydration at early age. The hydration process is particularly strongly retarded in the presence of Pb compounds. As a consequence, the compressive strength at early age is very low. In case of nitrates there is no additional products formed. However, one can observe that the properties of pastes admixtured with nitrates decline from those found in case of reference The calcium silicate phase becomes less fibrous but more compact, with very small individual particles, as the nucleation from the liquid phase is disturbed. There are the accompanying cations incorporated in this product.
Larbi Belagraa, Meddah Abdelaziz, Beddar Miloud
Study of the Physico-Mechanical Properties of a Recycled Concrete Incorporating Admixtures by the Means of NDT Methods
During the last decades, the sector of construction has known a growing trend in construction and demolition (C&D) activities. The management of the collected debris and waste causes real problems at the environmental level, which can be seen in the decrease space in urban area and the agriculture land occupied by the waste of demolition. At the moment, researchers in civil engineering domain are called to propose new solutions to find substitutions of the natural aggregate such as, the recycled aggregates (RA) as an alternative for natural crushed aggregates (CA). This study here in focuses on the use the recycled aggregates coming from old concrete tested specimens from construction sites. The aim of this research is the formulation of a recycled aggregate concrete (RAC) within similar performances (resistance and durability) to conventional concrete (CAC). The superplastizier as admixture at dosages 0%, 0.5%, 1%, 1.5% and 2% was combined with a recycled aggregate at 100% replacement. The physico-mechanical properties at fresh and hard state were investigated, mainly the density, absorption, air content, elastic modulus and strengths. In addition the NDT test methods (ultrasonic and rebound hammer) were used to assess the compressive strength of the due concrete. The correlation study of strength (Rc) and the properties; such as elastic dynamic modulus (Ed), ultrasonic velocity (V), rebound hammer number (Is), absorption (A) and the density (γ) to predict the compressive strength in this particular case was considered.
Teresa Stryszewska, Stanisław Kańka, Agnieszka Żydzik-Białek
Research Methods Adopted for Evaluation of the Condition of the Building Materials Used in Construction of the Masonry Structures on the Site of the Auschwitz-Birkenau State Museum in Oświęcim
The article shows the extent of work carried out within the framework of the project Research on the development of methods of maintenance, security and strengthening the structure of objects, elements of their finish and substrate, taking into account the statics and physics of the buildings within the Auschwitz-Birkenau State Museum in Oswiecim, as part of the multi-annual program of comprehensive, systematic preservation activities aimed at preserving the Auschwitz-Birkenau Memorial. The project is funded by the Auschwitz-Birkenau Foundation.
The aim of the project was to create a base of information on the actual condition of the existing facilities and, on that basis, to develop preservation methods and ways to prevent their further destruction while maintaining their current character.
The article presents the results of the research into the condition of the structural materials done – as an example – on one of the elements of the camp technical infrastructure – the wastewater treatment station. It also describes how the research itself was done. The scope included finding out the compressive strength of the masonry, bricks and mortar as well as determining the content of sulphate, chloride and nitrate salts both in the bricks and mortar. The article discusses the results of macroscopic and microscopic observations done on bricks and mortar using scanning microscopy.
Jerzy Wawrzeńczyk, Wioletta Kozak
A Method of Analyzing the Porous Microstructure in Air-Entrained Concrete on the Basis on 2D Image Analysis
The number of air voids, their size and disposition in cement paste,are important characteristics, which substantially affect the system of air voids that protects concrete from freezing and thawing cycles. The standard spacing factor L is based on the simplified Powers model, which assumes that all bubbles have the same diameter and are distributed in cube corners. A better solution is provided by Philleo, which determines the percentage content of protected paste (S*). The authors’ approach consists in determining the PPV factor, which is based on the concept of Philleo, and takes into account not onlythe actual structure of air voids, butalso of aggregate grains, which is often disregarded in analyses. In this article the results of analyzing the air void structure in air-entrained concrete on the basis on 2D image analysis are presented. Implementation of this research was possible thanks to the use of a special procedure of concrete samples preparation.Such an approach allows the separation of 4 phases of concrete: aggregate, cement paste, rings of the paste protected by air voids and air. The PPV results obtained from image analysis were compared with standard spacing factor L and with Philleo factor (S*).The authors are of the opinion that the 2D analysis proposed in the study will make it possible to describe more accurately the air-void system in air-entrained concrete.
Anna Dudzińska, Anna Kotowicz
Features of Materials versus Thermal Comfort in a Passive Building
Summer time is especially difficult to provide optimal conditions of the microclimate in heavily used areas. Choosing optimal materials and construction solutions is essential and can guarantee maintaining comfortable conditions inside the building in all seasons, even when outside temperatures reach high levels. This article focuses primarily on the effect of the heat capacity of construction materials on the thermal comfort in a passive school building. Cellular concrete, silicate blocks and solid brick were analyzed. The simulation was performed from 15th May to 15th September. Results presented in this article show that in order to protect the building from overheating, heavy materials with a high heat capacity are the most effective. In case when highly conductive materials were used, it can be observed that lower inner temperatures appear during summer and predicted mean vote values are close to the thermal comfort zone.
Przemysław Buczyński, Maciej Lech
The Impact of One-, Two- and Three-component Hydraulic Road Binder on the Properties of the Hydraulically Bound Mixture
The paper presents the results of tests on road base used in the construction and maintenance of roads stabilised with hydraulic binders. Seven hydraulic binder mixes were prepared under laboratory conditions by mixing three basic components: Portland cement CEM I 32.5 R, fluidized bed combustion ash (PF) and cement kiln dust (CKD). The proportions of the binder components were established in accordance with the experimental design. The percentage share of the hydraulic road binder in the bound mix was 6%. Two types of natural aggregates were used for the base. The percentage shares of the individual components in the mix were designed using the Proctor method. For pastes, made from binders, basic mechanical properties were determined. To assess the effect of binders on the properties of the base stabilised with hydraulically bound mixtures tests were conducted to measure the following: compressive strength after 7, 14, 28 and 42 days of curing, freeze-thaw resistance. Experimental results demonstrate that it is possible to determine the optimal composition of hydraulic binders for the required strength class of the base course.
Karolina Gibas, Michał A. Glinicki, Daria Jóźwiak-Niedźwiedzka, Mariusz Dąbrowski, Grzegorz Nowowiejski, Michał Gryziński
Properties of the Thirty Years Old Concrete in Unfinished Żarnowiec Nuclear Power Plant
The construction of Żarnowiec Nuclear Power Plant (NPP) facilities was discontinued in 1989, despite the high level of work advancement. Already a large part of the concrete structures was built, now submerged in water from Żarnowieckie Lake. These structures were exposed over 30 years to the environmental conditions (rain, and varying high and low temperatures) without any special maintenance treatment. The technological documentation archives are not available. Experimental testing of specimens drilled out from different concrete structure elements was performed in September 2014.
The goal of the research was the identification of the composition of concrete and its present properties, especially the recognition of the effects of long-term environmental impact. The scope of the research covered macroscopic and microscopic analysis of concrete, compressive strength test, permeability test defined as the rate of chloride ions migration and water absorption. Unfortunately, the most important parts of the concrete structure are not available for testing because they are under water level. The obtained results allowed to classify the concrete structural elements in nuclear power plants buildings as of a quite good quality.
Martina Ivaskova, Peter Kotes, Miroslav Brodnan
Air Pollution as an Important Factor in Construction Materials Deterioration in Slovak Republic
Climatic parameters and atmospheric pollution are highly relevant to the degradation of several building materials like construction metallic materials, concrete structures and plasters of buildings, bridges or art sculptures. Degradation of not only metal materials, but also other construction materials (concrete, glass, etc.) by chemical environmental loads is an increasingly serious problem not only in Slovakia, but all over the world. The atmosphere and, ultimately, the hydrosphere could be particularly polluted by industrial activity, thus causing an increased corrosion aggressiveness of atmosphere. In the article, the air pollution impact on stone materials and carbon steel in Slovak Republic is observed. In the evaluation, there are used dose-response functions, which were developed based on long-term research by the other authors. Effectively, multi-annual climatic parameters and parameters of air pollution in Slovak Republic were used for generation of the maps of annual average surface loss of stone materials and carbon steel.
One of the priorities of that research is creation of corrosion maps of different materials, which do not help to protect materials, but could be useful for prediction of risks during design, analysis and maintenance. The values obtained from this interpolation of the maps would be used as a basis for a long-term research work in mapping the state of degradation of various materials in Slovak Republic.
Paweł Sikora, Paweł Łukowski, Krzysztof Cendrowski, Elżbieta Horszczaruk, Ewa Mijowska
The Effect of Nanosilica on the Mechanical Properties of polymer-Cement Composites (PCC)
In the last decade nanomaterials due to their unique physical and chemical properties, have attracted the interest of researchers to fabricate new building materials with novel functions. One of the most referred to and used cementitious nanosized materials is nanosilica (nSiO2). Although the number of publications devoted to the influence of nanosilica on the properties of cementitious composites has increased over the course of the last decade, the field of polymer-cement composites (PCC) has remained under-studied. Therefore, this paper will deal with the potential application and the influence of nanosilica (nSiO2) on the mechanical properties of PCC.
In this study the influence of diameter (100 nm and 250 nm) and quantity (1%, 3%, 5% by weight of cement) of nSiO2 on the consistency and mechanical properties of polymer-cement mortars (PCC) have been examined. Moreover, the hydration of cement compounds was followed by X-ray diffraction (XRD).
Studies have shown that the addition of nanosilica has great potential to accelerate the pozzolanic reaction, thus reacting more with the CH and increasing conversion of C-S-H, and having the potential to improve mechanical properties of PCC. The obstacle overcome is the high water demand of nanosilica particles, leading to significant deterioration of consistency. Finer particles of nSiO2 seem to be more effective and cause fewer problems with the consistency of fresh mortars.
Pawel Sikora, Elzbieta Horszczaruk, Teresa Rucinska
The Effect of Nanosilica and Titanium Dioxide on the Mechanical and Self-Cleaning Properties of Waste-Glass Cement Mortar
The recycling of waste glass is a major problem for municipalities worldwide due to high disposal costs and environmental concerns. Recycling glass from the municipal solid waste stream in order to manufacture new glass products is limited due to high costs, impurities, and mixed color. Although colorless waste glass has been recycled effectively, colored waste glass with its low recycling rate, has mostly been dumped into landfills. Due to its high level of impurity, colored glass cannot be processed easily. A new use was found for it, instead of creating waste: an additive in building materials.
In this study, the self-cleaning properties and strength development characteristics of mortar containing waste glass and nanomaterials (nanosilica – nSiO2 and titanium dioxide – TiO2) are analyzed in terms of waste glass content and the effectiveness of commercially available nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50% and 100% by weight. The photodegradation of the rhodamine B test has been conducted to analyze the effect of titanium dioxide, nanosilica and waste glass presence in the cement mortar for its potential application in self-cleaning façades. Studies have shown that waste glass can act as a successful replacement for sand, especially when mixed partially with sand. Additionally, a positive influence of nanomaterials on the self-cleaning and mechanical properties was noted.
Katarzyna Łaskawiec, Małgorzata Piotrowicz, Piotr Romanowski, Piotr Wojciechowski
Basic Characteristics of Concrete Durability as the Criteria for Curing Classes Selection According to EN 13670:2009
In EN 13670:2009 standard: Execution of concrete structures there are general rules of moisture curing of concrete in structures. In the standard 4 classes of concrete curing are described. Determination of curing class depends on required level of compressive strength immediately after curing (percentage of required characteristic strength after 28 days). Time of curing depends on rate of strength development and concrete surface temperature. In the standard there is a lack of information about influence of curing class on concrete durability characteristics.
The main condition to obtain durable concrete is proper curing regime. Not cured on improperly cured concrete has weakened surface layer. Extremely faults in curing process could lead to defects visible on the concrete surface. More often defects are latent inside the concrete and could be revealed during exploitation, leading to durability reduction. The main effect is increase of surface layer porosity (reinforcement cover) and decrease of its protective properties and tightness. Consequently worsening of mechanical properties could be observed as well as water-tightness, frost resistance, chemical aggression resistance, carbonation resistance and diffusivity of chloride.
The analysis shown in the paper are the result of 3-yers long investigation conducted by authors, which main goal was to determine appropriateness and way to include durability requirements in designing of curing class according to EN 13670:2009. Thawing-freezing resistance, scaling with salts resistance, depth of water penetration under pressure and absorptivity were adopted as the basic durability factors. Concretes with different cement types, different rate of compressive strength development, air-entrained and non-air-entrained were tested. Time of curing was differentiated in the range of classes 1,3,4 following standard EN 13670:2009 requirements. Practical conclusions were formulated which allows to consider durability presumptions in technological requirements contained in concrete works specifications.
Daria Jóźwiak-Niedźwiedzka, Karolina Gibas, Andrzej M. Brandt, Michał A. Glinicki, Mariusz Dąbrowski, Piotr Denis
Mineral Composition of Heavy Aggregates for Nuclear Shielding Concrete in Relation to Alkali-silica Reaction
The results of microscopic analysis on thin sections of aggregates intended for nuclear shielding concrete are presented. The petrographic analysis was performed on different barite, magnetite and hematite aggregates used as the high-density aggregate to absorb gamma radiation. Both optical microscopy and accelerated expansion tests were used to recognise the potential for alkali-reactivity of the aggregates. The mineral composition of the tested aggregates was analysed on thin sections in transmitted cross-polarized light and XRD tests were additionally performed. Expansion tests of mortar bars exposed to 1 N NaOH solution at the temperature of 80 °C were also performed following ASTM C1260. The high-density aggregates contained ore deposits - metallic opaque phases providing the required shielding properties. These aggregates also contained various amounts of non-metallic phases, with both innocuous non-ore minerals and deleterious, potentially reactive materials. Barite aggregates contained siderite, fluorite and hawleyite in varying amounts, apart from the barium sulphate being the principal component. Moreover, particularly reactive cristobalite and muscovite were identified in barite aggregates from certain quarries. Tests according to ASTM C1260 performed on mortars showed the expansion above the accepted criterion for non-reactive aggregate and confirmed the threat due to the presence of cristobalite in barite aggregates.
Jan Małolepszy, Ewelina Grabowska
Sulphate Attack Resistance of Cement with Zeolite Additive
Concrete as one of the most common building material, exposed to groundwater, soil and seawater is often object to sulphate attack. Partial replacement of Portland cement by natural zeolite has been proven to be effective in reducing sulphate attack. The results of cement sulphate resistance after 52 weeks in Na2SO4 solution are presented. The sulphate resistance of mortars was examined by determination of linear changes of specimens immersed in Na2SO4 solution. The studies of microstructure of cement mortars were carried out by scanning electron microscope equipped with energy dispersive spectrometer (EDS). Investigation includes also pictures of samples after 32 weeks exposition in corrosion solution.
Zbigniew Rusin, Przemysław Świercz, Zdzisława Owsiak
Effect of Microstructure on Frost Durability of Rock in the Context of Diagnostic Needs
Problematic rock classification criteria used in civil engineering require correction. Particular attention should be paid to frost resistance test methods and criteria of acceptable absorption levels. The classification of frost resistance levels may be incorrect due to insufficient number of freeze-thaw cycles, and the criterion of rock absorption is inaccurate. Based on the results of research completed to date, the authors conclude that all rocks with capillary volumetric absorption below 0.6% are highly frost resistant, regardless of their origin. All rocks with capillary volumetric absorption above 1.5% are not frost resistant to a greater or lesser degree. Rocks with capillary volumetric absorption between 0.6% and 1.5% may show both low and high frost resistance. This group of rocks is characterized in this article. The structural features compared include mineralogical composition (derivatography and X-ray analysis), appearance and size of crystallite (analysis with an optical microscope, and SEM). The texture features evaluated include total porosity, pore size distribution MIP, capillary water absorption, vacuum absorption, and the degree of filling the pores with water. It has been found that increasing the number of freeze-thaw cycles allows better assessment of the rock's potential durability. The capillary water absorption in combination with the degree of filling the pores can be an effective durability indicator for use in the classification of rock construction products.
Abdelaziz Meddah, Larbi Belagraa, Miloud Beddar
Effect of the Fibre Geometry on the Flexural Properties of Reinforced Steel Fibre Refractory Concrete
Steel fibres are commonly used in refractory industry to reinforce high temperature concretes. Little information is available on the effect of fibre geometry on the refractory concrete and in particular to thermal shock. Eleven different melt extract fibre geometries were investigated with fibre lengths of 10 mm, 25 mm and 50 mm and aspect ratios varying from 14 to 108. Beam specimens made from a proprietary dense hydraulically bonded castable, reinforced with 5% by weight of steel fibre, were cyclically heated and colled on one face in a specially designed spalling furnace to condition them in a simulated service environment Flexural tests were conducted at service and room temperature to obtain toughness indices. The relationship between fibre geometry and toughness indices is discussed.
Miłosz Szybilski, Wiesława Nocuń-Wczelik
The Effect of Dolomite Additive on Cement Hydration
The effect of dolomite on alite hydration was investigated in order to elucidate the effect of dolomite addition in cement hydration. The rate of heat evolution both in cement – dolomite and alite – dolomite system was taken as a starting point. Subsequently the chemical shrinkage, conductivity of liquid phase and rheological parameters of pastes were characterized. The observations of microstructure were carried out under SEM and the hydration degree of alite was determined by XRD. The accelerating effect of additive was proved. At low percentage dolomite plays a role of cement replacement; at higher dosage – the „dilution” effect can be observed. However, increasing dolomite content is accompanied by higher amount of hydration products, as a results of crystallization on the fine dolomite grains and better absorption of water. The hydration degree of alite increases as well.
Pavel Liška, Barbora Nečasová, Jiří Šlanhof, Martina Šimáčková
Determination of Tensile Properties of Selected Building Sealants in Combination with High-pressure Compact Laminate (HPL)
One of the current issues in the Czech building industry is an efficient implementation of seal joint between constructions. An undesirable penetration of water, moisture or air between structural elements may have a negative effect on their reliability and may also affect the length of expected service life. This issue is addressed in detail in the following paper. The experimental part of the research is aimed at ascertaining the technical properties of sealants and on verification of their potential usage in practise. Furthermore, this article focuses on the preparation and subsequent production of test specimens, and also on the experimental verification of their tensile properties at a temperature of (20 ± 3) °C and (-22 ± 2) °C. For the tests, composite high pressure laminates (i.e. HPL Trespa Meteon) are chosen for the cladding. In order to find the best solution ten types of commonly manufactured industrial sealants is selected. At the same time the emphasis was on representation of sealants in various price categories. The main conclusion of tests is the fact that it is not possible to responsibly choose a suitable material without taking appropriate measurements or having previous experience. A secondary conclusion to this article is the fact that there are significant differences between individual sealants in the results they provide in combination with selected cladding material. Moreover, the method also suggests that the use of the most expensive sealant does not always provide the best results.
The Effect of Lightweight Aggregate Water Absorption on the Reduction of Water-cement Ratio in Fresh Concrete
The aim of this paper is to present the problem of water-cement ratio reduction in structural lightweight concrete as a result of mixing water absorption by the lightweight aggregate. The research was carried out on eighteen concrete mixtures made of sintered fly ash aggregate and cement pastes of different nominal water-cement ratios. It has been demonstrated that the rate and the extent of the absorption of mixing water by the aggregate in concrete is dependent not only on its water absorption, but also on its moisture content, moisture state, the procedure of concrete preparation and the concrete composition. Moreover, it has been proved that the standard method for calculation of the so-called effective water-cement ratio is accurate only in the case of high initial moisture content of the lightweight aggregate. When dry sintered fly ash aggregate is used, the standard method gives underestimated values of the ratio as compared to its actual values determined in tests.
The effect of mixing water absorption by the lightweight aggregate, revealed in tests of fresh concrete as the reduction of water-cement ratio, was also reflected in hardened state of concrete as the increase of its strength. The strength increase was higher for mixtures with higher content of lightweight aggregate. Although the porous aggregate is the weakest element in structural lightweight concrete, in this case its higher content may be compensated with excess by the stronger cement matrix resulting from the reduction of water-cement ratio.
Zdzisława Owsiak, Anna Sołtys, Przemysław Sztąboroski, Monika Mazur
Properties of Autoclaved Aerated Concrete with Halloysite Under Industrial Conditions
This paper presents the results from the study of the effect of halloysite powders on the performance of the slow-setting silicate-based autoclaved aerated concrete (SW production technology). The clay mineral was used as a cement replacement. The material was tested at industrial scale. The test results indicated relationships between halloysite chemical properties and the properties of the ready-made product. The most important properties of the mineral from the kaolinite group include high specific surface area and chemical composition. Physical and mechanical properties were tested in terms of bulk density, porosity, thermal conductivity and compressive strength of the finished product. In addition, the testing programme included determining the influence of halloysite on the phase composition and microstructure of the aerated concrete, using the XRD analysis and SEM imaging.
The Influence of Methylcellulose on the Hydration Process of C3S, C3A and Mixture of these Phases
The paper presents the results of investigation over influence of 0.3% addition of hydroxypropyl methylcellulose (MC) of 40 and 70 Pa·s viscosity on the hydration process of main clinker phases: C3S and C3A and also their mixture, both in presence and absence of gypsum.During the research it has been indicated that methylcellulose inhibits the hydration process of clinker phases, analyzed both separately and in their mixture. Moreover, presence of that additive reduces reactivity of calcium sulphatedihydrate what leads to formation of decreased amounts of ettringite. No significant differences resulting from viscosity of used methylcellulose were observed.
Investigation over the influence of that admixture on the hydration process of tricalcium aluminate indicated that addition of methylcellulose inhibits hydration process of C3A with water. Similar influence of that admixture was observed in the case of C3A hydration in presence of gypsum. A lot of gypsum remains in the reaction mixture. Little amounts of ettringite are forming, however, there is no monosulphate. Inhibition of sulphate ions reaction with C3A is slightly higher in the case of methylcellulose of higher plastic viscosity.Also in the hydration examinations of tricalcium silicate methylcellulose addition caused a retardation of alite reaction with water. In first hydration hours of alite with MC addition there were no peaks of portlandite in the XRD pattern. In the presence of gypsum the influence of methylcellulose addition on the hydration course was significantly weaker. Simultaneously no significant differences related to the influence of different plastic viscosity of methylcellulose were observed.Similar course of reactions was observed in the case of hydration of alite and tricalcium aluminate mixture in the presence of gypsum and methylcellulose. After one week of hydration significant amounts of unreacted gypsum are still remaining. However, little amounts of ettringite are created.
Nataša Marjanović, Miroslav Komljenović, Zvezdana Baščarević, Violeta Nikolić
Comparison of Two Alkali-activated Systems: Mechanically Activated Fly Ash and fly Ash-blast Furnace Slag Blends
Poor reactivity of fly ash (FA) in alkali activation process can be improved either by mechanical activation of fly ash or by blending fly ash with more reactive material, such as blast furnace slag (BFS). Both options were explored in this paper and comparison was performed. Mechanical activation of fly ash was conducted in a planetary ball mill, while blends of fly ash and blast furnace slag were prepared with different ratios (FA/(FA+BFS) = 1; 0.75; 0.50; 0.25; 0). Alkali activation was carried out at 95 °C by use of sodium silicate solution as an activator. In both cases significant increase of geopolymer strength was observed in respect to the geopolymer based on the initial fly ash. Optimal geopolymer strength was correlated with the chemical composition of the binding gel. Empirical values of optimal gel composition could serve as a basis for tailoring properties of alkali-activated binders based on different precursors. Both alkali-activated systems represent promissing routes for geopolymer technology development.
Alexey Kharitonov, Marina Korobkova, Olga Smirnova
The Influence of Low-hard Dispersed Additives on Impact Strength of Concrete
The article presents the results of experiments on the use dispersed components with reduced stiffness in concrete mixtures to assess their influence on the dynamic strength of concrete. A crushed ceramic bricks, the polystyrene foam, cellular glass and expanded clay sand were used components with reduced stiffness. Samples-cubes were subjected to various dynamic loads, and then measured their strength and were compared with the results obtained for a control sample. Furthermore by vertical dynamic koper were measured impact strength of the obtained compositions. The results of experimental studies are showing the possibility of increasing the impact strength of concrete by introducing into the concrete mix an additive with reduced stiffness. In the same time there is some reduction in other properties of the resulting concrete. Has been defined the optimum additive and its amount to use in the concrete that subjected to dynamic loads.
Magdalena Bacharz, Barbara Goszczyńska, Wiesław Trąmpczyński
Analysis of Destructive Processes in Unloaded Early-age Concrete with the Acoustic Emission Method
The study presents the analysis of destructive processes that occur in early-age concrete with the use of the IADP method of acoustic emission signal analysis. The tests were conducted for concrete specimens made with basalt aggregate, which was cured at a constant temperature of 22° C, but were different with respect to cement class, admixtures used and the curing methods. Three classes of AE signals were identified. The signals were generated by destructive processes related mainly to concrete shrinkage due to water evaporation and described as: microcracks at the aggregate – cement paste interface, microcracks in the cement paste, and the formation of microcracks on concrete surface. It was shown that the IADP method could be used to identify and evaluate the destructive processes that develop in early-age concrete.
Walid Deboucha, Mohamed Nadjib Oudjit, Abderrazak Bouzid, Larbi Belagraa
Effect of Incorporating Blast Furnace Slag and Natural Pozzolana on Compressive Strength and Capillary Water Absorption of Concrete
Blast furnace slag (BFS) and natural pozzolana (NP) have been widely used as a partial cement replacement in concrete construction due to their advantages including cost reduction and improvement of the ultimate mechanical and durability properties. Based on an ongoing experimental program, this research emphasizes on the effect of substituting cement with Blast furnace slag and natural pozzolana up to 40% on compressive strength and capillary water absorption of concrete. The compressive strength was determined on prisms at the ages of 7, 28, and 90 days. Cylindrical specimens were employed for capillary water absorption test after 28 days of curing. The results show that it is possible to obtain the same or better strength grades by replacing cement with BFS up to 30% in concrete. However, the use of NP content reduced the compressive strength. Lower capillary water absorption for BFS or NP substitution is observed.
Influence of Superplasticizer on Porosity Structures in Hardened Concretes
One of the criteria used to achieve frost resistant concrete is to obtain appropriate parameters of porosity structure in the hardened concrete. Polish requirements in this regard are not defined by standards. There is only a requirement in terms of the Spacing Factor for air-entraining admixtures contained in EN 934-2. The standard EN 206 to ensure frost resistance of concretes requires in exposure classes XF2-XF4 air content in fresh concretes at least 4% without verification of the porosity structure in the hardened concrete. The technical specifications for paving concretes and bridges usually contain requirements for parameters of porosity structures based on international requirements. Air entraining process of concrete mixtures is complex and depends on many parameters. The analysis of porosity structures in hardened concretes, despite the required frost resistance of concrete, often do not give satisfactory results. Analysis of the results indicates that the reason is inadequate pores sizes in the concretes. Thus, an attempt of explanation of influences of one of the parameters affecting the air entraining process – consistencyof concrete mixes (quantity of superplasticizer) on the porosity structure in the hardened concrete. The research programme was performed on eight series of air-entraining and non-air-entraining concretes with a variable content of superplasticizer. The basic composition and air-entraining admixtures content in air-entraining concrete mixtures were constant. The results showed that with the increase of the content of superplasticizer (with increasing fluidity) air content decreases and the pores sizes changed.
Jan Małolepszy, Piotr Stępień
The Influence of Gaize Addition on Sulphate Corrosion of CEM II/A and CEM II/B Cements
The paper presents and discusses the results of resistance to sulfate aggression cement mortars containing calcalerous gaize. Were tested cements containing 15-35% gaize (CEM II A, B) and the reference cement CEM I (no additive). Using DTA/TG, XRD investigated the effect of gaize on the hydration of cement. Linear change mortars were tested according to the procedure in PN-B-19707, complement the research was to determine the strength of the mortar as a result of following long-term storage of samples in corrosive environments. Mortar microstructure studies were performed using mercury porosimetry and SEM/EDS. The results of the study allow us to conclude that already 15% of the content of Gaize making cement resistant to corrosive environments rich in sulfate ions.
Mariusz Maślak, Ryszard Skiba
Fire Resistance Increase of Structural Steel through the Modification of its Chemical Composition
In the article the possibility for increasing the fire resistance of structural steel used in building load-bearing structures is presented and discussed in detail. The recommended approach is based on a suitable modification of its chemical composition, in particular by adding the carefully selected alloying elements. With such a change, not only a high-temperature strength of this material may be significantly increased in relation to that which would be achieved for the typical structural steel with an unmodified composition but also its sufficient weldability should be ensured by the entire duration of its exposure to a fire. The steel modified in this way would be undoubtedly more expensive to manufacture but due to the fact that it will not require any special protection against fire it seems that it can provide an interesting alternative to the solutions currently used in engineering practice.
Katarzyna Krzemień, Izabela Hager
Assessment of Concrete Susceptibility to Fire Spalling: A Report on the State-of-the-art in Testing Procedures
The assessment of concrete behavior at high temperature is done by a variety of tests carried out on specimens of different sizes. Small-scale tests examine concrete's behavior when exposed to elevated temperature, while full-scale fire tests are carried out on full-sized concrete elements in which the boundary conditions, external load and conditioning correspond to design assumptions. Complementary to these is the medium-scale test carried out on a portion of a slab's surface area which has been exposed to fire, ca. 1m2. Such medium-scale tests are often used as a cost-effective solution to verify the behavior of a specific concrete mix in fire conditions. This paper reviews the existing furnaces, testing procedures and laboratory setups used to assess a material's tendency to spall. Its objective is to emphasize the need to unify spalling risk assessment procedures by establishing recommended guidelines for testing.
Numerical Modeling Mechanical Delamination in Laminated Glass by XFEM
This paper deals with the three-dimensional modeling of laminated glass failure due to delamination of the glass. The extended finite element method is used here (XFEM) to input discontinuity to the approximation field. The regarded glass consists of two outer glass plies and thin inner layer of the polyvinyl butyral (PVB). The PVB inner layer is very thin in comparison to the laminated glass thickness. That is why in the model, presented in this paper, the PVB layer is not spatially discretized. However, the inner layer exists in the problem formulation. The constitutive law for PVB is written with the help of two dimensional inner layer traction vector. Finally it results in three-dimensional effective numerical model for delamination analysis. The model is illustrated with an example.
Elżbieta Stanaszek-Tomal, Teresa Stryszewska
Influence of Salting Mineral Materials on the Development of Fungi
In this paper presents the effects of the combined action of two aggressive environments. Then determine the effect of the content of sulphate ions or chloride on the growth of microorganisms and the possible impact of chemical-biological corrosion properties of moisture, mechanical structure of the ceramic materials.
To assess changes in the samples as a result of corrosion-induced chemical and fungi, the following parameters were selected: a chemical analysis, the goal was to determine the content of sulphate ions or chloride; pH; colony-forming units; mass moisture and absorbability of water, and research on the microstructure under the scanning electron microscope.
The results allowed to formulate a number of statements: ceramic materials are resistant to mould; original ceramic salt contamination of chloride ions or sulphate did not stop the operation of the biological environment; by the co-operation of both aggressive environments, material properties change.
Assessment of Mortar Shrinkage in Aspect of Organic and Inorganic Modifiers Use
The shrinkage of cement composites is a very important factor affecting their durability. This is an undesirable property from the technological point of view and hence the subject of many research activities. In the article the results of shrinkage of modified mortars is presented. Lime is a traditionally used additive that has a positive effect on the workability of mortars. In addition, mortar strength and adhesion increases when the lime is added in an amount about 10% c.m. to cement mortar. Among many modern admixtures three of them have been selected for testing. An air entraining and plasticizing admixture dosed at 0.3% c.m. was chosen as typical admixture for mortars (it is also advertised by the manufacturer as “replacing lime” admixture) and two polymer admixtures a styrene-butadiene copolymer and a polyvinyl alcohol both dosed at 5% c.m. The mortars shrinkage was tested in a standard way as well as by the modern system of the so called “gutter”. This system allows to record volume changes (shrinkage and expansion) from the beginning when cement composite is put to the gutter. The aim of the research was to determine the effect of mentioned modifiers on cement mortars shrinkage which was tested by two methods: standard and modern.
Tomasz Jaśniok, Mariusz Jaśniok
Influence of Rapid Changes of Moisture Content in Concrete and Temperature on Corrosion Rate of Reinforcing Steel
Electrochemical tests on corrosion rate of reinforcement were performed on six concrete specimens reinforced with a single bar equipped with temperature and concrete moisture sensors. The specimens were kept in a climatic and corrosion chamber where ambient temperature was changing discretely in a temperature range of 7 °C ÷ 35 °C, and similarly humid conditions were changing in a range of 30% ÷ 90%. The tests were also conducted on specimens immersed in water at 7 °C and 35 °C. Temperature and moisture content in concrete at the bar surface were monitored throughout the tests. The objective of this work was to analyse the influence of rapid changes in climatic conditions maintained for a few-day cycles, on corrosion rate of reinforcement in concrete. The tests demonstrated that the current corrosion process models for concrete reinforcement which assumed an immediate response of corrosion rate to a change in climatic conditions, was correct only for temperature.
The Effect of Lime and Cellulose Ether on Selected Properties of Plastering Mortar
The article presents the results of the investigation on the plastering mortars modified with lime and cellulose ether. Standard designations were performed and technological properties of plasters were determined. The performance of each plaster was rated, water retention ratio after 10, 30 and 60 minutes was determined and mechanical properties were described. An analysis of the effect of cellulose ether and lime on mortars’ setting and hardening time was performed by ultrasonic method. Rheological properties of the pastes concerning yield stress and plastic viscosity were determined as well. Although water retention for all mortars is at the same level, other parameters are highly varied. The results presented in the paper clearly show the effect of the cellulose ether and lime admixture on the standard properties and technological characteristics of both the material in the plastic state and the final product. The proper selection of the particular mortar components may have a decisive influence on the properties of the final product, therefore a comprehensive examination of the material is so important. The rating of the technical parameters of mortars presented in the paper can be a valuable source of information for contractors and construction materials producers.
Studies on the Effect of a Limited Polarization Range of Reinforcement on Impedance Spectra Shapes of Steel in Concrete
Polarization tests by impedance spectroscopy were conducted on single rebars in rectangular concrete specimens. Five different polarized areas of reinforcement were determined by means of an insulation tape on steel bars. The tests were conducted on two series of concrete specimens, with and without chlorides. The tests indicated a very clear effect of spectra “scaling” in a function of the change in reinforcement polarization area. The observed phenomenon was explained on the basis of the original 3D model of steel–concrete system.
Eneli Liisma, Gert Lõhmus, Lembi-Merike Raado
The Effect of Temperature and Humidity on the Permanence of External Thermal Insulation Composite Systems
The purpose of this paper is to analyze the impact of temperature and humidity on external thermal insulation composite systems (ETICS), resulting in internal stresses and frost damages as a serious sustainability problem. In order to predict the behavior of ETICS in different weather conditions, a variety of climatic conditions and cycles were composed on the basis of the Estonian statistical data. All coating components of ETICS were tested separately and as a system for dimensional changes using thin layer measurement principles. This study focuses on three types of plasters most commonly used in ETICS – mineral plasters, acrylic plasters with higher flexibility and silicone plasters. As a result of the research, a potential micro-cracking mechanism of ETICS in Northern climate conditions is presented in this paper.
Marcin Kozłowski, Marta Kadela, Alfred Kukiełka
Fracture Energy of Foamed Concrete Based on Three-Point Bending Test on Notched Beams
A series of static loading tests was performed to determine the fracture properties of foamed concrete of varying density. Beams with dimensions of 100×100×840 mm with a central notch were tested in three-point bending. Then, remaining halves of the specimens were tested again as un-notched beams in the same set-up with reduced distance between supports. The tests were performed in a hydraulic displacement controlled testing machine with a load capacity of 5 kN. Apart from measuring the loading and mid-span displacement, a crack mouth opening displacement (CMOD) was monitored. Based on the load – displacement curves of notched beams the values of fracture energy and tensile stress at failure were calculated. Subsequently, the flexural tensile strength was obtained on un-notched beams with dimensions of 100×100×420 mm. Moreover, cube specimens 150×150×150 mm were tested in compression to determine the compressive strength.
Implementation of Pore Microstructure Model Generator and Pore Space Analysis Tools
Mesoscale modelling of porous materials may require building explicit geometric models for porous microstructure. Such microstructure models are composed of connected voids (pores) embedded in an otherwise impermeable solid. Having such a model at hand it is possible to directly calculate several characteristics of the pore microstructure, for instance pore radii, pore lengths, pore wall surface area as well as spatial distribution statistics. Additionally, having a solver capable of simulating fluid flow through such model, it is possible to gain insight into the effects of pore microstructure characteristics on flow properties, both macroscopic, such as permeability, or microscopic, such as tortuosity. In their recent paper Hyman and Winter  discuss an algorithm for stochastic generation of explicit pore structures by thresholding Gaussian random fields. Unfortunately their paper is missing an discussion on effective implementation of the presented algorithm. In our paper we fill this void by providing detailed discussion on implementation side of the algorithm discussed by Hyman and Winter. Besides presenting a microstructure generator which we provide as Open Source program, this paper shows how generated model can exported to data formats suitable for analysis and visualisation with various tools, for instance data formats based on VTK library. The programs described in this paper can form a base for handy tools and reduce the programming effort of building simulation environment for materials microstructure analysis.
Małgorzata Niziurska, Jan Małolepszy, Grzegorz Malata
The Influence of Lithium Carbonate on Phase Composition of Calcium Aluminate Cement Paste
In the paper the results of experiment are presented which main goal was to examine the influence of lithium carbonate addition on the phase composition development of calcium aluminate cement. The study shows that the lithium carbonate has the significant influence on the reaction rate of alumina cement components and water. Very little addition of admixture (as 0.03%) causes the X-ray identifiable effect on calcium aluminate hydrates after 15 minutes mixing with water. Hydration products in the presence of lithium carbonate differ from the phases that occur in the case of alumina cement binder without the admixture. The article shows the test results for the monocalcium aluminate. A significant impact on the course of the hydration reaction is also confirmed by the results of calorimetric look into alumina cement and monocalcium aluminate paste.
Opportunities and Risks Arising from the Properties of FRP Materials Used for Structural Strengthening
Modern composite materials, made on the basis of non-metallic continuous fibers are increasingly used in civil engineering, in particular to strengthen building structures. In strengthening of RC structures the utilization of externally bonded FRP composites is only up to 35% because of the pilling-off failure mechanism. This problem can be solved by the use of pre-tensioned composite laminates. Due to more complex behavior, the strengthening of structures using prestressing technology needs a careful design approach and a full understanding of the behavior of both the materials and elements. The advantages and risks of the presented technology, which may determinate the success of the entire project, are highlighted in the article.
Olesya Izryadnova, Grigory Yakovlev, Lilya Nurieva, Stanislav Sychugov, Grigory Pervuchin
Role of Polyfunctional Admixture Based on Silica Fume and Carbon Nanotubes in Forming the Structure of Gypsum Cement Composition
One of the topical areas of regulating the structure of gypsum cement compositions is modifying the morphology with ultrafine and nanodisperse systems. The study has analyzed the possibility of changing the structure and properties of new formations of gypsum cement pozzolanic matrix by adding multifunctional admixture based on silica fume and multi-walled carbon nanotubes (MWCNTs) dispersed in a surfactant medium. The optimum content of complex admixture has been determined as 0.006% of MWCNTs and 10% volume content of silica fume as part of modified gypsum cement pozzolanic binder (GCPB) providing the increase of compressive strength by 55% and water resistance by 32%. Studying the structure of modified GCPB by means of physico-chemical analysis (scanning electron microscopy, infrared-spectral analysis and differential scanning calorimetry) has proved the improvement of physical and mechanical properties due to changes in mineralogical composition of new formations in hardening composition and morphology of the forming crystal hydrates in the structure of modified gypsum cement pozzolanic matrix. At the same time, it is noted that gypsum crystalline hydrates are coated with calcium silicate hydrates compacting the structure of the composition and increasing the total contact surface of the new formations. At the same time calcium silicate hydrates prevent water from the surface of crystals of calcium sulfate dihydrate, thereby increasing the water resistance of the composition.
Mária Kozlovská, Zuzana Struková, Pavol Kaleja
Methodology of Cost Parameter Estimation for Modern Methods of Construction Based on Wood
The modern building systems employ an unceasing development potential of latter building materials and systems. The composition of building structures (walls, roofs, floors, ...) is increasingly difficult due to combinations of various types of materials in order to ensure (create) the structures with the best parameters (thermo-technical, mechanical, user‘s, ....). The production cost, determining the further application of building components on the market, definitely presents one from important parameters. Especially in the area of wooden constructions, there have been increasingly appearing new and new construction-material systems. To explore their structural and material characteristics, the standard analysis, calculations and test procedures are used. However, the determination of their quantities, when estimating the total cost, is problematic. The existing estimating databases providing at least information cost, don’t involve the needed information. Thus, a potential customer is not able to confront the cost of such new construction systems with cost of other systems offered by various suppliers. The paper is focused on construction-technological analysis of the modern construction systems based on wood. Moreover, the proposed methodology of cost parameter estimation is presented. Estimation of Budgetary Index (BI) is based on a case study of a selected construction system based on wood, represented by ten wood houses with different shape and different size.
Bogusław Jarek, Aleksandra Kubik
The Examination of the Glass Fiber Reinforced Polymer Composite Rods in Terms of the Application for Concrete Reinforcement
GFRP (Glass Fiber Reinforced Polymer) rods have found a wide range of applications in building structures as reinforcement of concrete bearing elements. In no time on the market appeared a few producers who are offering a wide assortment of diameters. In this paper, applied test procedures and their results for GFRP rods are presented. Rods made by three manufacturers, with declared diameter 12 mm, have been analyzed. The tensile strength, elasticity modulus and ultimate limit strain, based on the static tensile test, were compared. These resultants were compared with tensile strength obtained for widespread use reinforcement steel AIIIN. Different results of composite rods destroying process are discussed. It worth stressing the great discrepancy between the declared and real diameter of tested rods, which may result in an inability to simple conversion between conventional steel reinforcement to composites in structural elements.
Sylwia Kucharczyk, Maciej Zajac, Jan Deja
The Influence of Limestone and Al2O3 Content in the Slag on the Performance of the Composite Cements
In the present contribution, the interaction between limestone and slag is investigated by a multi-method approach using chemical shrinkage, thermogravimetry, scanning electron microscopy (SEM) techniques and compressive strength measurements. The impact of limestone was investigated in blends containing synthetic slags of different alumina content. The results are correlated with the thermodynamic modelling in order to gain further insights into the physical and chemical processes governing the interaction between limestone, slag and Portland cement.
Beyond 28 days of hydration, slag composites exhibit higher compressive strength values than their equivalent with quartz. Increasing the Al2O3 content from 8 to 12% in slag influenced compressive strengths positively at all hydration times. Further increase of alumina in slag to 16% has no positive effect on strength. Addition of limestone, results positively only on early compressive strengths. After 28 days and longer effect of limestone is either slightly negative or neutral. Only in the case of the slag containing 16% of alumina, limestone has positive impact on the late compressive strength. The effect of limestone has two main components: physical, so called filler effect and chemical that depends on the slag composition.
Barbora Nečasová, Barbora Kovářová, Pavel Liška, Jiří Šlanhof
Determination of Adhesion of Silyl Modified Polymer Adhesives to Wooden Façade Cladding – Case Study
Adhesives are currently very often designed specifically for bonded façade systems. The potential of bonded joints should be studied and described in more detail and verified through experimental measurements. Presented results are therefore focused test methods intended for vented wooden façade systems with bonded joints. For the purpose of tests two types of silyl modified polymer adhesives intended for structural bonding were selected, however, only one of them is recommended for façade systems. The spruce profiles and three types of façade cladding (i.e. Cement-bonded particleboard - Cetris, Siberian larch and Wooden Plastic Composite - WPC) represent the structure of vented façade. The focus was on experimental verification thus all test procedures are following relevant European technical standards. The adhesive bonds were tested in adhesion of the surface finish to the substructure as well as in tensile lap - shear at a temperature of (20.0 ± 3) °C and a relative humidity of (55.0 ± 10) %. The performed tests showed the equivalence of the bonded joint system for ventilated facades in comparison with mechanical joints. During the tests appeared differences in stability and failure behaviour between the adhesive systems as well as within the sheeting material. Another conclusion arising from the series of tests is the fact that the use of a wooden substructure for ventilated facades is not a limiting element for the whole system and is a more financially viable option in comparison with an aluminum or steel substructure.
Influence of the Physicochemical Properties of Portland Cement on the Strength of Reactive Powder Concrete
The paper presents an analysis of mechanical properties and microstructure of reactive powder concretes RPC manufactured with the use of three different industrial Portland cements diversified in terms of the strength class (42.5 and 52.5), chemical and mineral composition as well as specific surface area. All developed materials were subjected to three different hydrothermal curing conditions. The test results confirm that the factors most influencing the consistency of the concrete mixture are the chemical and mineralogical composition of the binder. However, it appears that when it comes to mechanical properties, the factor which plays the crucial role is the specific surface area of cement. For one of the analysed cements, due to its favourable chemical and mineralogical composition, it was possible to limit the value of W/B ratio up to 0.17, without adversely affecting the properties of the concrete mixture. Nevertheless, it has not contributed to any spectacular increase in strength as compared to materials based on the cement with the largest surface area, where the minimum realizable W/B ratio was 0.20.
Anna Zastawna-Rumin, Katarzyna Nowak
Experimental Thermal Performance Analysis of Building Components Containing Phase Change Material (PCM)
The article presents the results of experimental studies of partitions containing phase change materials. The main objective of the measurements was to determine the actual effectiveness of the used materials and their impact on energy storage capabilities through building partitions. The light partition component containing a finishing layer of organic material undergoing a phase change was the subject of research. The heat flux and temperature distribution on individual component layers were recorded while changing the temperature conditions of the surrounding air. The cycle of temperature changes has been chosen to model the probable conditions inside buildings located on Polish territory. The results made it possible to determine the actual effect of PCM applications in partitions on heat accumulation capacity increase and thermal conditions of the component. The article also addresses the issue of determining the parameters of material for which a very strong dependence of the specific heat and temperature exist. When used in construction materials, phase-variable thermal properties of the materials used must be accurately known, since the system efficiency depends on the thermal properties of materials. The article presents an attempt to determine the properties of the PCM as a function of temperature using the equipment consisting of heat meter, electronic sensors and thermocouples temperature.
Anna Chomicz-Kowalska, Krzysztof Maciejewski
Multivariate Optimization of Recycled Road Base Cold Mixtures with Foamed Bitumen
The paper presents an approach for identifying the optimum range of foamed bitumen and Portland cement contents in recycled mineral-bitumen road base mixtures using simultaneous optimization of response variables (i.e. properties of mixtures estimated from statistical models) with the use of desirability functions. The 16 evaluated mixtures had a common aggregate composition comprising materials from existing pavement layers (reclaimed asphalt pavement and aggregates from recycled crushed stone base layer) and virgin material. The mixtures varied in foamed bitumen contents (2.0% - 3.5%) and Portland cement contents (1.0% - 2.5%). The investigated mixture parameters included: air void content (Vm), indirect tensile strength (ITS), tensile strength retained (TSR) and indirect tensile stiffness modulus (ITSM) at 25 °C. The use of the desirability functions and desirability index allowed to identify the effective and optimum range of binding agent dosing for the recycled mixture with respect to all of the measured mixture properties.
Performance of Building Materials and Whole Enclosures in Non-Stationary Thermal Conditions
Thermal performance of low energy buildings depends not only on the thermal resistance of the building enclosure but also on the dynamic features of a building's components. Stationary heat flow is relatively well understood and easy to calculate, whereas dynamic characteristics are a complicated concept and are always connected with more advanced computational tools. The commonly used harmonic model of non-stationary heat transfer is usually based on a 24-hour period, however, in real-life conditions the building's response to longer heat waves is also important. The dynamic features of selected materials and of the building's enclosure in transient environmental conditions are calculated and discussed in this paper. The influence of decisions concerning the selection of materials and thickness on internal conditions is discussed, and design decisions to ensure appropriate microclimate control are presented.
Paweł Walczak, Jan Małolepszy, Manuela Reben, Karol Rzepa
Mechanical Properties of Concrete Mortar Based on Mixture of CRT Glass Cullet and Fluidized Fly Ash
The problem with the waste from electric and electronic equipment (WEEE), consisting of about 80% of television sets and computers containing a cathode ray tube (CRT) have just begun to deal with. Cathode ray tubes (CRTs) are the video display components of televisions and computer monitors (EPA, 1995). Arising problem related with recovery and recycling of CRT glass stimulates examinations aimed at making cullet-based ceramic materials of reinforced mechanical strength. Glasses as cone and neck contain principally different lead contents another dangerous elements instead panel glass has other heavy metals (Ba, Sr, etc.) that forbid their recycling in the glass industry for the production of containers, domestic glassware and glass fiber. As it is well known concrete is an excellent material for immobilization of these metals, what was the reason to undertake this research. The use of CRT (Cathode Ray tube) waste glasses in concrete has attracted a lot of interest worldwide due to the increased disposal costs and environmental concerns. Because of silica large quantities CRT glass in the theory is a pozzolanic in nature, thus it can be used as a sand replacement in light concrete. The research was performed with use of concrete mortars. As a reference concrete mortar a mix of cement, sand, expanded clay aggregate and water was used. The purpose of this work was to investigate the influence of additives e.g. CRT glass cullet as an aggregate, and fluidized fly ash on concrete properties. Based on obtained results both CRT glass cullet and fluidize fly ash improved compressive and flexural strength in respect of standard concrete mortar without these additives. The use of CRT glass as a sand replacement caused the increased of compressive strength of concrete mortar of about 16% and its flexural strength of about 14%.
Justyna Mrugała, Mateusz M. Iwański
Resistance to Permanent Deformation of Asphalt Concrete with F-T Wax Modified Foamed Bitumen
Higher requirements concerning environmental protection and occupational health and safety entailed the development of new asphalt mix production technologies, characterized by production temperature lowered by 60 to 80 °C. In addition to environmental advantages, such bituminous mixtures also provide technological and economical benefits. The reference asphalt concrete AC 22W and experimental foamed bitumen asphalt modified with F-T wax was designed to respond to the requirements named above. The production and compaction temperature of the foamed bitumen asphalt was 95 °C (Half Warm Mix Asphalt). A traditional Hot Mix Asphalt was also produced for the purpose of comparison. The study investigated the effect of two factors: the amount of F-T synthetic wax (from 1.0% to 2.5% with an increment of 0.5%) and the amount of foamed bitumen (from 4.2 to 5.1, with an increment of 0.3%) on the development of permanent deformations in asphalt concrete, one of the most significant service parameters of the asphalt pavement. The results from the study indicate that the addition of F-T synthetic wax to the bitumen before foaming gives the asphalt concrete (produced at 95 °C) resistance to permanent deformations comparable to that of the traditional asphalt concrete, produced at a temperature of 160 °C.
Łukasz Zdanowicz, Paweł Kisiel, Arkadiusz Kwiecień
Stress Redistribution in Concrete Floor on Ground Due to Application of Polymer Flexible Joint to Fill Expansion Joint
A problem of filling a concrete floor expansion joint was described and an alternative material for filling the joint – polymer flexible joint (PFJ) was also presented. Basic properties of polymer flexible joints as a hyperelastic material were depicted with calibration of corresponding material coefficients. A numerical analysis of concrete shrinkage, applied in calculations as an equivalent of temperature load, with application of polymer flexible joint was conducted – for PS and PM polymer types. These cases were also compared with traditional bonding method (epoxy resin). Basic results of the numerical analysis were compared – such as displacements and reduced stresses according to Huber-Mises-Hencky hypothesis. Differences in stresses redistribution were observed between analyzed models whereas values of displacements were similar.
Zdzisława Owsiak, Agnieszka Mazur
Effect of Chalcedony Dust on ASR in Mortars of Reactive Aggregate
Chalcedony dust is a mineral addition which has pozzolanic properties, similar to fly ash. Pozzolanic in nature, chalcedony dust causes the increase of absorption of sodium and potassium ions by the CSH phase of lower C/S molar ratio, decreasing their concentration in the concrete pore solution, thus eliminating the concrete damaging by ASR. The paper presents the characteristics of chalcedony dust and the results from the studies of alkali expansion in cement mortars containing this admixture. Its contribution to reducing expansion was demonstrated in the study, along with the relationship between the amount of the chalcedony dust and the magnitude of expansion resulting from ASR.
Katarzyna Nowak-Dzieszko, Małgorzata Rojewska-Warchał
Influence of the Balcony Glazing Construction on Thermal Comfort of Apartments in Retrofitted Large Panel Buildings
This paper presents the results of the annual computational simulations conducted for separate flats of a ten-story W70 large-panel building. The calculations were carried out in the Design Builder program which prepares a simulation of the building envelope as well as the separate parts of the building interior. The simulations conducted for the polish climatic conditions allowed the assessment of the thermal comfort of the entire multi-family building and of the particular flats. It is very rare to take into consideration the requirements connected with the overheating effect in the panel buildings. This issue is closely related to the thermal comfort of the building, especially during the summer months. For the last couple of years modernization of large panel buildings has become very popular. Most of the multi-family large panel buildings in Poland have already been insulated, windows were exchanged and in many cases balconies were closed with glazing constructions. Based on conducted simulations authors analyzed the microclimate conditions in different apartments, with different orientation of balconies. Different simulation steps were analyzed which allowed an evaluation of the influence of different windows, loggia glazing framings and night cooling on microclimate in different apartments.
Peter Pavlov, Daniel Evlogiev
Experimental Determination of the Elastic-Viscous Characteristics of Elastic Ropes
The conducted analytical, numerical and experimental studies for waiving of the elastic-viscous characteristics of elastic ropes are presented in the current report. The analytical studies are related to the creation of a dynamic and mathematical model of a vibrating system, supported by such ropes. The numerical studies refer to the creation of a corresponding program and a simulation model. The experimental activities refer to the modification of an existing dynamic stand for the implementation of an experimental setting, corresponding to the initial dynamic model. Additional numerical activities are carried out in connection with the development of a programming module for receiving, processing and analysis of the results of the experimental studies. By applying of the combined procedure, the data for the resistance of randomly selected group of ropes, at different deformation in them, are received.
The Stiffness and Bearing Capacity of Polymer Flexible Joint under Shear Load
The results of a series of experimental laboratory and numerical tests of Polymer Flexible Joint (PFJ) under shear load have been presented in this paper. To determine the suitability of technology in practical use in precast concrete pavements it is very important to describe correctly the mechanical behavior of PFJ subjected to shear load. This work presents the results of 24 experimental laboratory tests performed on middle-sized PFJ specimens of various geometry loaded with shear. All specimens have been modeled in Abaqus 6.12. The convergence of data computed and tested has been shown for all variants. The results computed for a real scaled structure with PFJ have been also presented in the paper, providing a basis for further research and aiming at the implementation of this technology.
Effect of Selected Admixtures on the Properties of Ordinary Concrete
The article presents the results of laboratory research on the impact of polymer fibres and mineral dust on the properties of hardened concrete. Selected parameters such as compressive strength, flexural strength, water absorption and water capillary action were evaluated. The samples were cured at two temperatures: + 5° C and + 18° C. The polymer fibres added to ordinary concrete increased the resistance to bending and reduced water absorption and capillary action. Addition of mineral dust led to a general improvement of the test parameters, by sealing the cement paste. As shown in the absorption and capillary action tests, the gains in the mass of the samples decreased with the increasing amount of admixture in the form of mineral dust. The mineral dust used for laboratory testing was a waste material derived from an aggregate quarry. The dust is used to a small extent mostly for primers, for example. in the construction of roads. Although treated as a waste material, it has the same properties as original aggregate. Non-hazardous, it still has a negative impact on the environment. The use of aggregate mineral dust can bring a number of advantages, including lower price of concrete mix, improved concrete parameters, waste mineral dust disposal solution, lower cost production of concrete mixtures, and the environmental aspect. Concretes with mineral dust and polymer fibres are a valuable alternative to ordinary concrete.
Anna Perduta, Roman Putanowicz
Comparison of Elastomer Modelling in Various FEM Packages
No one can deny the role of synthetic polymers as engineering materials - they are all around us in our everyday life. Also due to the constant progress in material engineering, polymers, and among them elastomers, find increasing usage in civil engineering. Computer modelling of elastomers requires special description of material and use of non-linear finite element method. Available, free and commercial software use many different approaches in elastomers modelling, thus comparison of results may display discrepancies. Even if used method is the same, its computer implementation may vary, therefore using various software, one can obtain differing output.
The paper presents comparison of results obtained from four computational packages devoted to FEA: Abaqus, GetFEM++, Tochnog, FEBio. It can be seen as an overview of the software that can be used in modelling rubber-like components. It highlights differences in material description (for instance in names of hyperelastic laws and employed formulas) and used multi-field variational principles in modelling material's incompressibility. Examples included in the paper can be treated as benchmarks, that can be helpful in verifying third party software or the one developed by readers.
Dawid Pawłowski, Maciej Szumigała
Flexural Behaviour of Full-scale Basalt FRP RC Beams – Experimental and Numerical Studies
Basalt fiber-reinforced polymer (BFRP) bars are a relatively new material. Due to lack of experience in its use, behaviour of BFRP reinforced concrete (RC) members should be fully investigated. Furthermore, existing design codes for fiber-reinforced polymer (FRP) RC structures do not consider this type of reinforcement. This paper presents the results of an experimental and numerical study of the flexural behaviour of a series of simply supported BFRP RC beams under short-term static loads. The beams were varied in terms of the reinforcement ratio and the influence of this parameter was analysed. It had a significant effect on the stiffness and flexural strength of the beams. The members then were analyzed by the Finte Element Method. Good agreement between the results of the experimental and numerical studies were observed.
Dimensional Analysis can Improve Equations of the Model
In the past dimensional analysis was applied mostly to experimental research. Now, application of the analysis to model equations has become more important. Equations reformulated with the use of dimensional analysis are usually more clear and easier to handle computationally.
First, the article demonstrates the principles of dimensional analysis on the problem of the second moment of area for a rectangle. The transformation of equations to unit-independent form is discussed on the example of concrete constitutive equations. The equation that relates tensile and compressive strength of concrete is also analysed. Analysis of the equation obtained from experiments is demonstrated on the example of anchors.
Limitations of possibilities to formulate equations in units independent form are shown on the example of fracture.
Łukasz Bednarski, Rafał Sieńko, Tomasz Howiacki
Analysis of Rheological Phenomena in Reinforced Concrete Cross-section of Rędziński Bridge Pylon based on in Situ Measurements
The creep of concrete is a phenomenon that is often the cause of excessive deformation of the structure in serviceability limit state. In fact, creep strains are generally larger than elastic strains which occur on the application of load. Creep is affected by many factors both internal - related to the properties of specific concrete and external - related to the operating environment. In addition, attention should be paid to the fact that in real structures concrete almost always interacts with the reinforcement. This article examines the rheological phenomena that occur in the reinforced concrete cross-section of the Rędziński Bridge pylon in Wrocław, using in situ measurements from an automated structural health monitoring system.
Maciej Szumigała, Łukasz Polus
Applications of Aluminium and Concrete Composite Structures
The paper presents exemplary applications of aluminium and concrete composite structures. It discusses arguments for using these structures and reasons why in some cases it is advisable to replace a steel beam with an aluminium beam. Additionally, the article aims at analysing aluminium and concrete structures as a part of sustainable development. To this end, an analysis of materials used in aluminium and concrete composite structures was conducted. Moreover, the article presents a new method of joining an aluminium beam and a concrete slab, which may have a practical application.
Marcin Dyba, Łukasz Ślaga
Water Tower Materials Experimental Investigations and Technical Condition Assessment after 55 years of Exploitation
The purpose of this work was to define the technical condition of the water tower building and an indication of the ways of repairing and strengthening the structure. The function of the building is to provide water under high pressure to water supply installation for a water railway distribution station. The structure was built in 1959. The building consists of four floors above the ground and the basement. The main masonry structure is made of brick casted on lime and cement mortar. Each story is separated by reinforced concrete ceilings constructed as two-way slabs supported by beams. A circumferential reinforced concrete water tank is situated on the top floor. The tank consists of two chambers with the total volume of 250 m3. Reinforced concrete stairs are located around the circumferential wall of the building and provide service and technological communication in the building. The roof is constructed with reinforced concrete panels. The scope of the study includes a technical condition assessment of masonry walls, reinforced concrete floors (slabs and beams), stairs, the tank and the dome. For this reason, experimental researches on structural elements were performed. Researches of structural concrete include destructive tests made on drilling trial elements and non-destructive tests, to qualify mechanical properties of the material. Supplementary tests concern the humidity measurements and concrete alkalinity examination. For detection of rebar in structural elements, scanning of the specimen surface was performed and the concrete cover was removed in several places. For brick walls the main attention was focused on moisture content measurements. Experimental investigations and on-site inspections made it possible to assess the level of consumption of individual elements and durability of the structure. On this basis, main guidelines for necessary repairs and strengthening of structural elements which endanger the safety of exploitation were proposed.
Beata Łaźniewska-Piekarczyk, Janusz Szwabowski
Stability of Air-content in the Case of Innovative Air-entraining Portland Multicomponent Cement
The research results of the stability of air-entrainment in the case of innovative air-entraining multi-component CEM II/B-V are presented in this paper. Compatibility with innovative cement air-entraining CEM II/B-V plasticizers and superplasticizers were evaluated in terms of stability of air entrainment and maintenance of consistency for one hour of mortar according to PN-EN 480-1. The research results indicated that in case of a significant increase in the degree of liquidity of the air-entrained mortar or concrete made of participation of the innovative, air-entraining multi-component cement CEM II/B-V, first and new generation superplasticizers based on modified naphthalene, and then modified phosphoramidate should be used. The new generation superplasticizers based on polycarboxylate, polycarboxylic ether and acrylate cause a significant increase in the air-content of the air-entrained mortar and concrete.
Alina Kaleta, Stefania Grzeszczyk
The Influence of Chosen Factors on the Rheological Properties of Cement Paste
Rheological investigations were conducted into cement paste made of various cement types (CEM I 42.5 R, CEM II/B-S 42.5 R, CEM III/A 32.5 N LH/HSR/NA), with and without superplasticizer. The tests were performed at 15 °C, 20 °C and 25 °C, for one hour. Rheological parameters (yield value and plastic viscosity) were designated according to the Bingham model. The influences of hydration time, the presence of superplasticizer and of temperature on the occurrence of the thixotropy phenomenon in cement paste were identified. The thixotropy was analysed by measuring hysteresis loops surfaces using a numerical integral method.
The Influence of the Chemical Structure of Polycarboxylic Superplasticizers on their Effectiveness in Cement Pastes
The efficiency of polycarboxylic superplasticizers (derivatives of acrylic (SP-A and SP-B) or maleic (SP-C and SP-D) acids) after esterification with polyoxyethylene glycols (PEG) in cement pastes was analysed.
The chemical structure of the superplasticizers was defined by gel permeation chromatography (GPC) and Fourier transformed infrared spectroscopy (FTIR). According to the experimental results the superplasticizers - derivatives of maleic acid – display greater molar mass and are built from backbone polymaleic chains and very long side polyoxyethylene chains.
It is shown that acrylic superplasticizers display lower molar mass and are built from polyacrylic backbone chains and a higher number of shorter polyoxyethylene side chains. The efficiency o superplasticizers has been measured through their hydrophilicity, defined as the absorbance ratio of the ether band AET1110 (STRCH2–O–CH2ET) (referred to as the hydrophilic oxyethylene groups) to the ester band AES1730-40(STRC=OES) (referred to as the hydrophobic ester groups O=C–O–C) (with constant contents of aliphatic groups). A higher hydrophilicity of maleic superplasticizers, in comparison to acrylic, results from greater participation by the hydrophilic than the hydrophobic groups. It is shown that superplasticizers based on maleic anhydride derivatives (SP-C and SP-D) are more efficient than superplasticizers – acrylic acid derivatives (SP-A and SP-B).
Krystian Jurowski, Stefania Grzeszczyk
The Influence of Concrete Composition on Young's Modulus
This paper presents a dynamic method of concrete testing using Young's modulus. The advantages of the method are compared with the static method and the possibilities of application in practice are discussed. The procedure for concrete dynamic Young's modulus testing is presented. Young's modulus of concrete samples of different compositions have been tested by static and dynamic methods. Conclusions related to Young's modulus of concrete values obtained from static and dynamic testing methods and the influence of concrete composition on these values, have been drawn.
Kosmas K. Sideris, Christos Tassos, Alexandros Chatzopoulos
Production of Durable Self-compacting Concrete Using Ladle Furnace Slag (LFS) as Filler Material
Ladle furnace slag (LFS) is a by-product of the steel making process. In this paper ladle furnace slag was used as filler material for the production of self-compacting concrete mixtures of different strength classes. Different contents of ladle furnace slag filler, ranging from 45 to 92.5 kg/m3 were incorporated. The produced concretes were tested in the fresh state for fluidity, passing ability and resistance to segregation and in the hardened state for compressive strength, carbonation and chloride penetration resistance. The test results showed that ladle furnace slag can be used as filler for producing self-compacting concretes with enhanced durability characteristics resulting this way to lower cost environmentally friendly durable concrete mixtures.
Numerical Analysis of Stress Distribution in Concrete Around Corroding Rebar
Corrosion product formation, in particular swelling, affects the stress distribution around the corroded rebar in reinforced structures. The area around the rebar is dominated by tensile stress, which is the cause of crack formation in the concrete cover. The paper presents mathematical and numerical models to describe the mechanical effects of corrosion product formation. Two types of corrosion uniform and pitting are considered and some examples are presented, which confirm the usability of the presented models.
Maria Kaszynska, Adam Zielinski
Effect of Lightweight Aggregate on Minimizing Autogenous Shrinkage in Self-consolidating Concrete
Cracking is one of the main reasons for reduction of concrete durability, as it allows for penetration of water and aggressive chemicals leading to corrosion of rebars, deterioration and structural failure. Recently, rapid new developments in the new generation of concrete reveal the need for a better assessment of shrinkage and its effect on structural performance, as well as prevention and control of shrinkage. The shrinkage test methods that are codified in Poland (Graf-Kaufman and Amsler methods) allow for measurement of shrinkage deformation after removal of the forms, i.e. after 24 hours. In case of the new generation concrete with a low w/c ratio, the autogenous shrinkage is very important in the initial period of binding and hardening of concrete (up to 24 hours from casting). This paper presents the results of autogenous shrinkage tests for mortar and concrete. The autogenous shrinkage was tested using Auto-Shrink method. The crack resistance of concrete with regard to shrinkage deformations was tested using a ring-test method according to the ASTM Standard C 1698-09. Because autogenous shrinkage cannot be controlled by exterior curing procedures, the shrinkage tests were performed with light-weight aggregates saturated with water. Use of light-weight aggregates (LWA) allows for “interior curing” based on gradual release of water from presaturated LWA balancing interior moisture content. In addition, the effect of shrinkage reducing admixture on deformations of internally cured concrete was also tested. The test results confirmed the advantage of the considered internal curing for concrete. Internal curing can be successfully applied to concrete structures with low w/c ratio.
Tomasz Piotrowski, Michał Mazgaj, Andrzej Żak, Janusz Skubalski
Importance of Atomic Composition and Moisture Content of Cement based Composites in Neutron Radiation Shielding
Monte Carlo computer simulations confirmed that an increase in density has a minor effect on the weakening of neutron transport and, therefore, the optimum composition of a shielding concrete against gamma radiation is different than the one against neutron radiation. Neutron radiation shielding is a two-step process: slowing down of fast neutrons and absorption of thermal ones. Both result from the atomic composition of the barrier but their dependence on specified atomic compositions and moisture content is different. The aim of the presented research is to develop a high density concrete the composition of which would also assure good efficiency of neutron shielding. Neutron transport through standard cement mortar, PCC mortar, normal-weight concrete and magnetite heavy-weight concrete has been analyzed in the paper. The goal in research was to find an influence of the cement type, polymer addition, density and moisture content on the shielding properties against neutron. The research based on convergent results of MC computer simulations and real experiments confirmed the influence of the cement type on fast neutron attenuation. It was also found that each 1% of moisture content makes 10% increase of fast neutron thermalization effectiveness, what is a little less than it was estimated for cement based mortars. It was also proved that heavy-weight concrete is not proper solution for shielding against fast neutrons, but its efficiency is visible in the case of thermal neutrons absorption, probably due to increase of Fe content at the expense of Si and O in the atomic composition as well as water retained by magnetite aggregate.
Rostislav Drochytka, Ester Helanová
Development of Microstructure of the Fly Ash Aerated Concrete in time
Calcium hydro-silicate components formed during the autoclaving process are highly complex formations which often blend together mutually and form a variety of intermediate products, from completely amorphous, to the good crystalline phases. For fly ash autoclaved aerated concrete, the situation is even more complicated by the fact that high temperature and fluidized fly ash, as basic silica ingredients, have high variability of the chemical and mineralogical composition. This paper presents the results of microstructure monitoring and physical and mechanical tests on samples of fly ash aerated concrete based on high temperature and fluidized fly ashes performed after 2 years of storage in laboratory conditions. The microstructure of aerated concrete is assessed on the basis of SEM images and mineralogical composition according to X-ray analysis. The changes in compressive strength, density and coefficient of thermal conductivity of the fly ash aerated concrete in time are evaluated.
Magdaléna Kociánová, Vít Černý, Rostislav Drochytka
Development of Grout for Additional Seal Embankment Dams
The technology of sealing sand and gravel by chemical injection has been known and used for a long time. Chemical grouting is however expensive and sometimes the use of cement does not lead to the desired effect. That is why we are trying to find new materials and methods of injection. Clay and cement are added to a mixture save chemical products. Clay-cement mixes are used not only because they are better quality, but also because these mixtures have a tendency to penetrate better into incoherent sediments that would need an additional sealant of a chemical injection. In order to reduce cost in future, ordinary clay is replaces in the mixture secondary raw materials can be a suitable substitute for ordinary clay to a certain extent. This is true above all for fly ash. This paper deals with the appropriateness of using fly ash (secondary raw material), cement and lime (binders) and liquefying additives and examining their properties in the mixture. The aim of the paper is to propose the optimal injection mixture for additional sealing of earth dams.
Jakub Hodul, Božena Dohnálková, Rostislav Drochytka
Solidification of Hazardous Waste with the Aim of Material Utilization of Solidification Products
In order to reduce the amount of hazardous waste this work deals with the possibility of using solidification technology to transform the hazardous waste with the aim to achieve the material utilization of solidification products. For this purpose, it is necessary to determine a suitable solidification formula for solidification product made of the chosen hazardous waste – neutralization sludge. Particular solidification formula is chosen on the basis of advanced experimental examination of solidification products. Solidification products have to comply with the environmental requirements and physical and mechanical properties arising from their suitable further use in building industry or for land rehabilitation processes.
Sanita Rubene, Martins Vilnitis, Juris Noviks
Frequency Analysis for EIS Measurements in Autoclaved Aerated Concrete Constructions
In time of energy saving it is important to monitor humidity migration process through delimiting constructions. Autoclaved aerated concrete (AAC) is considered to be one of the most efficient load bearing construction materials in aspect of thermo insulation. For AAC it is important to determine the distribution of humidity throughout the cross section of the construction because it influences the thermic resistance of the construction. Therefore, it is important to monitor the drying process of AAC masonry constructions. This aim can be reached by non-destructive testing methods, which are easily applicable on inhabited buildings as well as on buildings, which are in construction phase. One of such methods is electrical impedance spectrometry (EIS), which can be used for determining of humidity distribution throughout the cross section of the construction. For this non-destructive testing method, it is important to choose correct measurement frequency in order to obtain credible results of humidity distribution. In this paper, methods of choosing suitable measurement frequencies are described as well as impact of different factors on choosing of the most suitable measurement frequencies of AAC masonry constructions.
Concrete Strength Development Function According to MC 2010 in the Light of Tests
The issue of accuracy in calculation of concrete compressive strength, especially for a maturity period longer than 28 days, is useful in some calculations during designing concrete structures. The MC 2010 pre-standard and the PN-EN 1992-1-1 standard provide the equation for calculations of fcm(t) including material ratio is dependent only on the strength class of cement. The paper evaluates accuracy of this approach with the example of a large set of research results for concrete of varied level of strength and quality of cements.
Multi-criteria Assessment of an Acrylic Coating Exposed to Natural and Artificial Weathering
The paper presents an assessment of durability of an acrylic coating weathered both under natural and artificial conditions. The effect of various degradation factors on service life of the material has been presented. The material in question is used to protect concrete against carbonation. Some diagnostic instruments, such as FTIR analysis, Scanning Electron Microscopy (SEM) and examination of barrier properties and adherence to the concrete substrate, have been used to determine the weathering rate of the material.
The Effect of Exposition Conditions on the Durability of Cement Concrete with Dolomite Aggregate Sourced Near Kraków, Poland
Some dolomite aggregates exposed to a wet environment may decompose. The presence of sodium, magnesium, calcium and sulfate ions in the corrosive medium and the higher temperature can increase the rate of aggregate decomposition.
The results of a study on the impact of defined environmental exposition to a H2O, Mg(OH)2, MgSO4, Na2SO4 solutions in various temperature conditions on the susceptibility to dedolomitisation processes of cement concrete made with selected dolomite aggregate are presented in the paper. The observation of linear extension as well as changes in compressive strength and surface alteration due to corrosive exposition conditions were the key diagnostic features adopted for this examination.
Wioletta Jackiewicz-Rek, Kamil Załęgowski, Andrzej Garbacz, Benoit Bissonnette
Properties of Cement Mortars Modified with Ceramic Waste Fillers
The paper presents the results of an experimental program intended to assess the potential of sanitary ceramic waste utilization as aggregates in cement-based mortars. Their influence was evaluated with respect to workability (consistency, plasticity, pores volume), mechanical properties (compressive and flexural strength) and freeze-thaw resistance. The results showed that partial replacement of fine aggregate with sanitary ceramic fillers up to 20% of cement by weight improves compressive and flexural strength and reduces shrinkage. The test results were discussed in the lights of the literature data on influence of ceramic waste on properties of fresh and hardened concretes.