MATBUD’2020
Scientific -Technical Conference: E-mobility, Sustainable Materials and Technologies

2020

Izabela Hager and Tomasz Tracz
Preface

This article has no abstract.

Link EN

Dana Konakova, Eva Vejmelkova, Lenka Scheinherrova, Martin Keppert, An Cheng and Robert Cerny
Basic physical and mechanical properties of cement composites after temperature exposure

Basic physical and mechanical properties of several cement composites are determined as functions of thermal load and the results are compared with reference materials. Bulk density, matrix density, and open porosity are measured using the water vacuum saturation method. Compressive and bending strengths are determined according to the European standard. High-temperature coefficient of thermal expansion is obtained using a comparative measurement. Experimental results show that composites based on Portland cement do not resist high temperatures well. Their applicability is limited to 400 °C, due to the damage caused by hydrates decomposition. On the other hand, composites based on calcium aluminate cement exhibit a better thermal stability and retain residual strength even after being exposed to 1000 °C.

Link EN

Jozef Švajlenka and Mária Kozlovská
The potential of timber-based buildings in terms of energy efficiency

The topic of energy efficiency is currently under discussion. One of the areas of energy efficiency is the energy efficiency of buildings. The thermo-technical requirements for building envelope structures are gaining increasing importance due to new legislation and technical regulations regarding the reduction of heating and energy demands of buildings over time and because of continuously increasing energy prices. Building construction and the operational costs of buildings are among the largest consumers of material and energy resources and environmental pollutants. Ecological constructions are a response to the current state of the environment. A suitable solution that represents ecological construction, operation and comfortable living is the construction of low-energy and passive houses based on wood. Wood-based buildings have many benefits that are particularly timely in the context of sustainability today. The aim of this paper is to introduce selected aspects of wood-based buildings in the context of energy efficiency and thus to reduce the adverse effects of construction on the surrounding environment.

Link EN

Wei-Ting Lin, An Cheng, Michał Łach, Krzysztof Miernik and Kinga Korniejenko
The binding properties of cementitious materials using circulating fluidized bed co-fired fly ash and pulverised coal fly ash

This study aims to investigate the binding properties of co-fired fly ash (CFFA) in paste and mortar specimens. Paste specimens containing various CFFA proportions (25%, 50%, 75%, 100% by weight of cement) were conducted and evaluated using setting time tests, water demand tests and compressive strength tests. Mortar specimens containing various CFFA and Pulverised coal fly ash (PCFA) proportions (10%, 20%, 30% by weight of cement) were also conducted and compared with regard to flowability and compressive strength. The test results indicated that the water demand increased as the amount of CFFA replacement increased on the flow level at 110±3%; this is due to the higher ignition loss (L.O.I.). Higher L.O.I. values mean that there are more unburned carbon particles in the CFFA and that most of these carbon particles are porous. The compressive strength of mortar specimens decreased as the amount of CFFA replacement increased. Compared to the chemical compositions of cement (C3S, C2S), the main components of CFFA (Ca(OH)2, CaCO3, CaO) have lower crystalline strength and compactness. Therefore, the higher amount of CFFA replacement would inevitably cause a reduction of the cement contents of specimens, thereby reducing the compressive strength of the mortar specimens. Thus, an appropriate amount of superplasticiser and CFFA replacement in the mixture is useful with regard to the binding properties of cementitious materials.

Link EN

Kinga Korniejenko, Dariusz Mierzwiński, Roland Szabó, Nóra Papné Halyag, Petr Louda, Eythor Rafn Thorhallsson and Gábor Mucsi
The impact of the curing process on the efflorescence and mechanical properties of basalt fibre reinforced fly ash-based geopolymer composites

Efflorescence is one of the limitations of the widespread use of geopolymers. This problem is caused by excess unreacted sodium oxide remaining inside materials. Unreacted sodium oxide creates white efflorescence on the surface of the produced material in the form of sodium carbonate heptahydrate Na2CO3∙ 7H2O. It decreases not only the aesthetic value of the final products, but also the mechanical properties of the material. The aim of this article is to analyse the influence of the curing method on the appearance of efflorescence on geopolymer composites reinforced by short basalt, especially on mechanical properties. Class F fly ash from the ‘Skawina’ coal-fired power plant (located in Skawina, Lesser Poland, Poland) was used as raw material for the geopolymerization process. The article compares two methods of curing: typical laboratory conditions (in the air) and samples submerged in water. Three series of fly ash-based geopolymer were cast: basalt fibres were added as 1% and 2% by weight of fly ash and one control series without any fibres. The investigation was performed using visual analysis, including microstructure investigation, and the testing of mechanical properties (compressive strength at ambient temperature) after 28 days.

Link EN

Adrian Chajec
Towards the sustainable use of granite powder waste for manufacturing of cementitious composites

The article is devoted to the description of the current state of knowledge about the possibilities of sustainable use of granite powder waste for manufacturing of cementitious composites. Granite powder waste is waste material resulting from the treatment of granite stone. In dry form, it is harmful to the environment and causes its degradation. One way to reduce its harmful effects is to use it for the sustainable production of cement composites and to use it as supplementary cementitious material (SCM). The results of researches carried out so far related to the impact of granite powder waste on the properties of fresh and hardened cementitious mixes are described. These results were compared and research gaps related to these studies were indicated. In summary, conclusions have been pointed out that indicate that granite powder waste can potentially be used as supplementary cementitious material, but comprehensive, comprehensive research related to this additive should also be carried out.

Link EN

Václav Kočí, Magdaléna Doleželová, Lukáš Fiala and Tomasz Tracz
The hygrothermal performance of concrete with coarse aggregates made of recycled concrete pavements

This paper deals with an investigation of the hygrothermal performance of concretes containing various amounts of recycled aggregates originating from crushed concrete pavements. The performance, which was obtained using computational modelling of coupled heat and moisture transport, is predicted on stand-alone samples as well as on built in samples in a real construction exposed to weather data of Ostrava, Czech Republic. The results revealed that the influence of recycled aggregates as substitution for natural stone does not negatively affect the hygrothermal performance of the concrete. The highest difference found was less than 1°C and 12% of RH in the case of stand-alone samples and only 2.2% of RH when built in. Therefore, the application of crushed concrete pavements as aggregates in concrete composition can be highly recommended as it brings other benefits such as economical and environmental.

Link EN

Václav Kočí, Magdaléna Doleželová, Lukáš Fiala and Tomasz Tracz
The hygrothermal performance of concrete with coarse aggregates made of recycled concrete pavements

This paper deals with an investigation of the hygrothermal performance of concretes containing various amounts of recycled aggregates originating from crushed concrete pavements. The performance, which was obtained using computational modelling of coupled heat and moisture transport, is predicted on stand-alone samples as well as on built in samples in a real construction exposed to weather data of Ostrava, Czech Republic. The results revealed that the influence of recycled aggregates as substitution for natural stone does not negatively affect the hygrothermal performance of the concrete. The highest difference found was less than 1°C and 12% of RH in the case of stand-alone samples and only 2.2% of RH when built in. Therefore, the application of crushed concrete pavements as aggregates in concrete composition can be highly recommended as it brings other benefits such as economical and environmental.

Link EN

Lukáš Fiala, Magdaléna Doleželová, Václav Kočí, Wei-Ting Lin and Izabela Hager
Basic Physical, Mechanical, Thermal and Hygric Properties of Concrete with Coarse Aggregates Fabricated from Recycled Concrete Pavements

Concrete production unfavourably affects the environment due to high energy demands of cement production and consumption of limited natural resources. Therefore, waste utilization in fabrication of cementitious material is beneficial and legitimate. Significant reduction of environmental impact can be secured by utilization of various types of wastes or byproducts used for a partial substitution of cement binder or aggregates. However, the use of waste materials usually leads to deterioration of material properties of the designed composites. Therefore, it is very important to thoroughly investigate important materials properties to verify performance and practical usability of the newly designed materials. In this paper, three types of concrete mixes were designed. The reference concrete involved fine and coarse natural riverbed aggregates and two other mixes were designed using both, natural and recycled aggregates represented by crushed concrete paving cobbles. Concretes were tested in terms of basic physical properties (bulk density), mechanical properties (compressive strength), thermal properties (thermal conductivity, specific heat capacity, thermal diffusivity), and hygric properties (water vapour diffusion resistance factor, water vapour sorption at 97% RH, water absorption coefficient, moisture diffusivity) and experimentally determined data were compared and discussed. It was observed that materials properties of concretes with recycled aggregates are comparable with those of the reference concrete which is a promising fact from the environmental point of view.

Link EN

Dariusz Mierzwiński, Janusz Walter and Piotr Olkiewicz
The influence of alkaline activator concentration on the apparent activation energy of alkali-activated materials

The aim of this article is to analyse the changes of apparent activation energy (Ea) of alkali-activated materials (AAM) at temperatures up to 100°C. Apparent activation energy (Ea) refers to the minimum amount of energy is required for the occurrence of reaction. The existing AAM research is based on assumptions about Portland cement (OPC). A number of studies have been conducted on the development of concrete strength depending on, inter alia, the duration of seasoning and the liquid to solid ratio (L/S). Based on the apparent activation energy and taking into account the effect of time and temperature at the same time, the physical and mechanical properties of OPC can also be predicted. The influence of the activator on the solidification process should also be taken into account for alkali-activated materials. This article shows the effect of changes in the concentration of the alkaline solution used in the AAM process on activation energy. The synthesized AAM material uses a solution based on water glass, sodium hydroxide, sand and volatile ash from the ‘Skawina’ coal-fired power plant (located in Skawina, Lesser Poland). The chemical composition of the material used is classified as class F ash. The concentration of the alkaline solution was 8M, 10M, 12M and 14M. The described research method was based on the use of thermistors with a negative temperature factor. It enabled prediction of the physical and mechanical properties of the materials tested. The results clearly indicate that this method can be used to determine the activation energy of the AAM. However, when determining apparent activation energy (Ea), the time and activation temperature of the binding processes of these types of materials should be taken into consideration

Link EN

Wei-Ting Lin, An Cheng and Robert Černý
Effect of limestone powder on strength and permeability of cementitious mortars

This study investigated the mechanical properties and durability of mortar specimens containing various quantities of waste limestone powder (0%, 10%, 20%, and 30% of the weight of cement). The mechanical properties were evaluated in terms of flowability, compressive strength, and splitting tensile strength. Permeability was evaluated in terms of resistivity, absorption, and rapid chloride penetration (total charge- passed). Test results revealed that replacing 10% of the cement with limestone powder improves both mechanical performance and durability. However, reducing the cement content reduced the availability of hydration products to fill the pores in the microstructure. The hydration product of limestone powder was mainly calcium hydroxide, which undermines the development of strength in the paste. Nonetheless, our results indicate that waste limestone powder is suitable for the partial replacement of cement

Link EN

Tomisław Gołębiowski, Bogdan Piwakowski and Michał Ćwiklik
Application of the GPR and ERT methods for non-invasive examination of a flood dike

As part of the NAWA-EMMAT project, geophysical surveys were carried out on selected sites in Poland, i.e. on the flood dike and in the surrounding of the concrete water dam. The goal of the surveys was the non- invasive detection of loose zones in the flood dike and fractured zones located in the subsoil of the water dam. Terrain geophysical measurements were conducted with the use of electrical and electromagnetic methods as well as applying seismic methods. Due to the limitations of the length of this paper, only selected results recorded on the flood dike using selected geophysical methods, i.e. electrical resistivity tomography (ERT) and ground penetrating radar (GPR) are presented. The presence of several higher hydraulic permeability zones in the dike was suggested by the results of the ERT method. The GPR method allowed, due to its high resolution, to identify small leakage zones in the body of the dike. An attempt at a quantitative interpretation of the geophysical data was made; for this purpose, the synthetic results obtained from numerical modelling of electrical and electromagnetic fields were applied. For proper construction of numerical models and further interpretation, the results of geotechnical sounding, geological drilling and the results of petrophysical measurements were also used.

Link EN