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Self-sensing properties of alkali-activated slag composites under compressive loading
Míková, Maria ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
Production of construction materials requires a large amount of energy. That can be decreased by using of waste materials. This thesis deals with the self-sensing properties of composites. It presents electrical properties of building materials and their measurement. In the experimental part, the influence of conductive fillers on the self-sensing properties of aluminosilicate composites was examined. Test cubes were made of alkali-activated slag with a content of graphite powder, carbon black, carbon fibers, steel fibers or carbon nanotubes. The fractional change in resistence during cyclic compressive loading was monitored.
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Proposition of conductive silicate composite for heating
Surovcová, Jana ; Černý, Vít (referee) ; Drochytka, Rostislav (advisor)
The bachelor's thesis deals with the development of electrically conductive silicate composite with the self heating value designed for surfaces in the exterior, on which an ice layer can form during the winter. The developed silicate composite should replace the defrosting of surfaces with chemical defrosting substances, which could have an adverse impact on the environment and are usually applied with a delay when a sudden change of weather appears. The theoretical part of this thesis summarizes the theory of electric field and electric current conduction, approached the issue of silicate binders, various types of electrically conductive phases and presents the current state of knowledge in the field of research of self heated composites. The practical part contains an assessment of selected effects of the exposure environment, based on which the requirements for the developed composite are formulated. Furthermore, the practical part is devoted to the analysis of necessary materials for producing self heated composite, so the focus is on conductive fillers. Selected fillers with the low level of the impedance are then used in the proposed recipes and the production of test specimens for the comparison of real parameters and the required ones. The work succeeded in proving the ability of heating the silicate composite with a conductive filler by means of an electric current, while the required mechanical parameters were not achieved. The bachelor thesis serves as a suitable basis for further research linked to the issue of electrically conductive self heated silicate composites.
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Electrically conductive composites based on secondary raw materials
Baránek, Šimon ; Šteffan,, Pavel (referee) ; Černý, Vít (advisor)
Electroconductive composites are modern materials that are commonly used in many industries such as the construction industry among others. For example these materials can be useful as sensors for monitoring changes in constructions. The aim of this thesis is the research of electrically conductive silicate composite based on secondary raw materials. The design of this composite is based on the development of its own mixtures and experimental verification of the effect of the structure. The introduction part consists of a detailed analysis of 15 materials. Samples of the 5 fine and 2 coarse electrically conductive fillers were tested. Composite with filler Condufit C4 was selected as representative for type of fine fillers. Composite with filler Supragraphite C300 was selected as representative for type of coarse fillers. The selection of the composites was based on the impedance of the fabricated composites with these fillers. Subsequently, the individual components of the primary mixture were substituted. The cement was replaced by high-temperature fly ash in the amount of 20, 30, and 40 %, the aggregate of a similar fraction was replaced by steel sawdust, and the primary electrically conductive fillers were replaced by secondary ones in the amount of 30 and 50 %. All proposed replacements reduced the impedance of the composite. The most effective replacement for impedance reduction was replacement with waste graphite (up to 92 % reduction), which also slightly improved the mechanical properties of the composite. The result of this thesis is an optimized electrically conductive composite based on secondary raw materials with a fine type of filler with 30 % replacement by waste graphite "odpad vysavač"which achieves an impedance of 5 ohms. The partial goal of this thesis is a verification of the influence of moisture on the impedance of composites. Results are significantly affected by moisture when using the coarse type of filler, when using the fine type are not.
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Silicate materials with enhanced electrical conductivity
Míková, Maria ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
This bachelor thesis deals with electrical properties of cement- or aluminosilicate-based materials used in building industry. It presents the summary of the most commonly used functional fillers with ability to increase conduction of the composites and theirs characteristics. Thesis also deals with measured electrical properties and applications of composites with enhanced electrical conductivity. In the experimental part, the influence of graphite powder concentration on the characteristics of alkali activated slag was examined. Electrical, mechanical properties and microstructure was observed. Microstructure was examined by means of mercury porosimetry and scanning elektron microscopy.
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Effect of moisture on the electrical properties of silicate composites
Karlíková, Helena ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
This work deals with study on the dependence of electrical properties on the moisture content in silicate composites. The theoretical part contains information about the electrical properties of cement-based and alkali-activated binders, as well as knowledge on moisture parameters and the presence of moisture in the material structure. Samples of cement-based mortars and alkali-activated slag with a graphite powder in the range of 0–18 per cent by weight were produced and quartz sand was used as filler in the experimental part. The samples were provided with copper electrodes and saturated with water after hardening. The electrical properties of the mortars were monitored by means of impedance spectroscopy during the gradual drying of the samples. The effect of microstructure has been studied using scanning electron microscopy and mercury intrusion porosimetry. The results indicate that a significant increase in electrical resistance occurs only when the relative sorption humidity content is below 20 per cent in the 40–5000 Hz frequency range.
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Effect of moisture on the electrical properties of silicate composites
Karlíková, Helena ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
This work deals with study on the dependence of electrical properties on the moisture content in silicate composites. The theoretical part contains information about the electrical properties of cement-based and alkali-activated binders, as well as knowledge on moisture parameters and the presence of moisture in the material structure. Samples of cement-based mortars and alkali-activated slag with a graphite powder in the range of 0–18 per cent by weight were produced and quartz sand was used as filler in the experimental part. The samples were provided with copper electrodes and saturated with water after hardening. The electrical properties of the mortars were monitored by means of impedance spectroscopy during the gradual drying of the samples. The effect of microstructure has been studied using scanning electron microscopy and mercury intrusion porosimetry. The results indicate that a significant increase in electrical resistance occurs only when the relative sorption humidity content is below 20 per cent in the 40–5000 Hz frequency range.
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Proposition of conductive silicate composite for heating
Surovcová, Jana ; Černý, Vít (referee) ; Drochytka, Rostislav (advisor)
The bachelor's thesis deals with the development of electrically conductive silicate composite with the self heating value designed for surfaces in the exterior, on which an ice layer can form during the winter. The developed silicate composite should replace the defrosting of surfaces with chemical defrosting substances, which could have an adverse impact on the environment and are usually applied with a delay when a sudden change of weather appears. The theoretical part of this thesis summarizes the theory of electric field and electric current conduction, approached the issue of silicate binders, various types of electrically conductive phases and presents the current state of knowledge in the field of research of self heated composites. The practical part contains an assessment of selected effects of the exposure environment, based on which the requirements for the developed composite are formulated. Furthermore, the practical part is devoted to the analysis of necessary materials for producing self heated composite, so the focus is on conductive fillers. Selected fillers with the low level of the impedance are then used in the proposed recipes and the production of test specimens for the comparison of real parameters and the required ones. The work succeeded in proving the ability of heating the silicate composite with a conductive filler by means of an electric current, while the required mechanical parameters were not achieved. The bachelor thesis serves as a suitable basis for further research linked to the issue of electrically conductive self heated silicate composites.
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Electrically conductive composites based on secondary raw materials
Baránek, Šimon ; Šteffan,, Pavel (referee) ; Černý, Vít (advisor)
Electroconductive composites are modern materials that are commonly used in many industries such as the construction industry among others. For example these materials can be useful as sensors for monitoring changes in constructions. The aim of this thesis is the research of electrically conductive silicate composite based on secondary raw materials. The design of this composite is based on the development of its own mixtures and experimental verification of the effect of the structure. The introduction part consists of a detailed analysis of 15 materials. Samples of the 5 fine and 2 coarse electrically conductive fillers were tested. Composite with filler Condufit C4 was selected as representative for type of fine fillers. Composite with filler Supragraphite C300 was selected as representative for type of coarse fillers. The selection of the composites was based on the impedance of the fabricated composites with these fillers. Subsequently, the individual components of the primary mixture were substituted. The cement was replaced by high-temperature fly ash in the amount of 20, 30, and 40 %, the aggregate of a similar fraction was replaced by steel sawdust, and the primary electrically conductive fillers were replaced by secondary ones in the amount of 30 and 50 %. All proposed replacements reduced the impedance of the composite. The most effective replacement for impedance reduction was replacement with waste graphite (up to 92 % reduction), which also slightly improved the mechanical properties of the composite. The result of this thesis is an optimized electrically conductive composite based on secondary raw materials with a fine type of filler with 30 % replacement by waste graphite "odpad vysavač"which achieves an impedance of 5 ohms. The partial goal of this thesis is a verification of the influence of moisture on the impedance of composites. Results are significantly affected by moisture when using the coarse type of filler, when using the fine type are not.
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Self-sensing properties of alkali-activated slag composites under compressive loading
Míková, Maria ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
Production of construction materials requires a large amount of energy. That can be decreased by using of waste materials. This thesis deals with the self-sensing properties of composites. It presents electrical properties of building materials and their measurement. In the experimental part, the influence of conductive fillers on the self-sensing properties of aluminosilicate composites was examined. Test cubes were made of alkali-activated slag with a content of graphite powder, carbon black, carbon fibers, steel fibers or carbon nanotubes. The fractional change in resistence during cyclic compressive loading was monitored.
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Silicate materials with enhanced electrical conductivity
Míková, Maria ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
This bachelor thesis deals with electrical properties of cement- or aluminosilicate-based materials used in building industry. It presents the summary of the most commonly used functional fillers with ability to increase conduction of the composites and theirs characteristics. Thesis also deals with measured electrical properties and applications of composites with enhanced electrical conductivity. In the experimental part, the influence of graphite powder concentration on the characteristics of alkali activated slag was examined. Electrical, mechanical properties and microstructure was observed. Microstructure was examined by means of mercury porosimetry and scanning elektron microscopy.
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