National Repository of Grey Literature 88 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
EFFECTS OF ABRASIVES DURING ACCELERATED\nSIMULATION OF MECHANICAL CORROSION OF CEMENT COMPOSITES USING ABRASIVE WATER FLOW
Hlaváček, Petr ; Sitek, Libor ; Klichová, Dagmar ; Bodnárová, L.
The paper deals with the use of the abrasive water flow technology in an accelerated simulation of the process of mechanical degradation of surface layers of cement-based composites by flowing liquids. Effects of the abrasive particle size and the mass flow rate of abrasives in an abrasive water flow impacting on the surface of concrete samples have been studied. In addition, suitability of the application of the abrasive water flow for the simulation of real situation of the surface wear by flowing liquids has been evaluated.
Cement Composite for 3D Printing Technology
Lipoldová, Marie ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
3D printing technology represents a fast-growing industry within many industrial sectors. This bachelor thesis is focused on possibilities of using 3D printing technology in building industry. In the theoretical part there are stated typical technologies and realizations of 3D printing in the field of construction. The thesis also includes a research which is essential for the determination of requirements for cement composites for 3D printing technologies including tests for verification of their properties. The experimental part of the bachelor thesis is focused on testing of various recipes of cementitious composites, especially on the properties of both fresh and hardened composites. Two batches were tested for the suitability of utilisation of waste PET particles.
The effect of appication of fine organic fibers to cement composites
Kavka, Lukáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This bachelor thesis describes the effect of using fine organic fibers in cement composites. In the theoretical part of bachelor thesis a composite material was defined and his individual components were described. Then was created a research of information about organic fibers focused on natural fibers. The basic parameters of cellulosic fibers and polypropylene fibers, the effect on the properties of cement composites and their application in practice were described. In the practical part there were created a reference concrete and 3 types of concrete with the addition of various types of organic fibers. The influence of fiber addition on the properties of fresh and hardened concrete were investigated. Another task of practical part was monitored the resistance of cellulose fibers in acidic and alkaline media in which the tested fibers were deposited. The development of pH solutions was examined over time.
The diploma thesis was prepared in cooperation with Atemit. The thesis describes the specific composition and properties of polymer industrial substrates from Atemit research.
Šácha, Dominik ; Tesařík, Miroslav (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis has goal to find out possibility of substitution sand in polymer crete flooring system by recycling car glass. Polymer crete is made from sand and epoxy resin. Companies use it in industrial flooring system. Polymercrete industrial flooring systems are new types of floor surface. It aims to customers with high requirements to floor properties and short time of realisation. Polymercrete floors are 4-6 mm thin. They are waterproof, they has higher compressive strength then 60 MPa and tensile strength is more than 20 MPa. Polymercretes does not make dust. This study includes also suggestion of recycling process to make glass sand from car glass windows. The diploma thesis was prepared in cooperation with company Atemit, s.r.o.
Verification of properties of concretes with nanoparticles
Pacltová, Klára ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with the influence of addition of carbon nanoparticles on cement composites. The theoretical part of the diploma thesis is focused on the research of information about carbon nanoparticles, more precisely about carbon nanotubes and graphene oxide. There are summarized methods of dispersing carbon nanotubes and their effects on cement composites. The practical part follows the theoretical part of the research. In the first phase, the correct technique of graphene oxide dispersion was verified. Subsequently, the effects of graphene oxide on the mechanical properties of cement mortars were verified. In the final phase of the diploma thesis, the knowledge gained from the previous part was verified on concrete samples.
Study of the influence of aggregate composition on volume changes and mechanical properties of High Performance Concrete
Vobinušková, Kristýna ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The master´s thesis deals with the volume changes of concrete during its concrete glow. These volume changes are generally more susceptible to high-strength concretes – HSC, which contain a bigger dose of binder. The theoretical section describes the possible reduction volume change especially in HSC, which are focused on the composition of concrete, especially on the type and particle size distribution of aggregate. Then attention is also paid to the different types of cements and their possible substitution. The part of the theoretical work describes the types of volume changes that may occur. In the experimental part are suggested the HSC by to secure informations. Different kinds of aggregates are used and a continuous or discontinuous grain curve and a different maximum grain size. Part of the sample was made only from CEM I 42,5 R and the second part of the sample from CEM I 42,5 R with the addition of very finely ground limestone. In terms of the part of the work were monitored volume changes of concrete with different composition and also their mechanical properties after 7, 28 and 90 days. Specifically, compressive strength, tensile strength, strength of the surface layers of concrete, water absorption and water-permeability test concrete. In conclusion, are listed all the results of tests.
Use of FRP Composites as Reinforcing Material for Concrete
Kratochvílová, Denisa ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
Because FRP composites have high fiber strength and good durability, they are increasingly used for repairs, modernisation and reconstruction of concrete structures. In practice, however there is a risk of premature separation of FRP reinforcement from concrete. This can be avoided by appropriate selecting the fibers and the matrix and the appropriate shape of the reinforcement. The actual materials and consistency of FRP reinforcement with concrete are also covered by this diploma thesis.
Monitoring the influence of concrete composition on abrasion resistance
Černá, Hana ; Novosad, Petr (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis focuses on the resistance of concrete to abrasion with regard to the raw materials used for their production. In the theoretical part of the thesis are described admixtures, different types of aggregate and aggregate composition which influence the resistance of concrete to abrasion. In the experimental part, 15 different C30 / 37, S4 concrete formulations were proposed. Different types of aggregates - fecal gravel (Žabčice), biotic granodiorite (Olbramovice) and amphibolite (Želešice) have always been used in the recipes. Fine ground limestone, micro-silica, high-temperature fly ash and finely ground slag were ingredients that were added to the proposed recipes. Consistency was determined by the method of cone seating and the density of fresh concrete. In the hardened state, concrete density, compressive strength, bending tensile strength, tensile strength, watertightness, concrete absorption, and abrasion resistance were determined using the Böhm method and wide wheel method. The test specimens were tested after 7, 28, and 90 days of maturation.
Study of properties of cementitious composites with fiber reinforcement from inorganic fibers
Gottwaldová, Aneta ; Novosad, Petr (referee) ; Bodnárová, Lenka (advisor)
Diploma thesis deals with study of properties of cementious composites with fiber reinforcement from glass and basalt inorganic fibers. Diploma thesis includes a theoretical and experimental part. The theoretical part deals with information about glass and basalt fibers, their durability and usage. In the experimental part we monitored properfies of cement composites with basalt and glass fibers. Fibers were exposed to an aggressive environment. The properties of composites with reference fibers were compared with composites with fibers affacted by the aggressive environment. The properties of composites were examined after 28 and 90 days. We monitored compresive strenght, bending tensile strenght, tensile strenght, surface layer strenght and SEM.
Use of nanotechnologies, especially CNT, in silicate composites
Jarolím, Tomáš ; Bodnárová, Lenka (referee) ; Martinec,, Petr (referee) ; Kalina,, Michal (referee) ; Hela, Rudolf (advisor)
Thesis theme were nanomaterials and its implementation to cementitious materials. Theoretical part has deal with description of carbon nanotubes types, their properties, production, ways of dispergation, nanotoxicity and CNT’s influence on silicate composites characteristics. Experimental part was divided to 5 stages. The first stages were focused on choosing appropriate carbon nanotubes and surfactants. In the next stage settings of US homogenizator were determinate (amplitude, US energy dosage, time). The part of US homogenizator setting process was observing influence of liquid environment characteristics (especially pH) on surface tension and particle distribution and influence of US energy on CNT walls damages through TEM. After dispergation parameters optimalization cement pastes were prepared and hydration temperature, hydration heat and viscosity were observed. Then testing specimens from cement mortar were prepared and tested form strength characteristics. Last stage was concrete production and their examination: compressive strength, flexural strength, static modulus of elasticity, dynamic modulus of elasticity, tensile splitting strength, depth of penetration of water under pressure, resistance of cement concrete surface to water and defrosting chemicals and determination of frost resistance of concrete. Samples with CNT addition had better strength characteristics and better resistance of penetration of water under pressure, water and defrosting chemicals resistance and frost resistance. Result of thesis is comprehensive study of CNT dispersion production and implementation CNT dispersion to concrete including testing specific concrete characteristics.

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