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Influencing the hydration of high-performance composites using zinc ions
Všetečka, Tomáš ; Hajzler, Jan (referee) ; Novotný, Radoslav (advisor)
The bachelor thesis is focused on the influence of hydration of high-performance cementitious composites, more specifically reactive powder composites. Zinc ions were supplied by the compounds of zinc oxide and zinc sulphate heptahydrate. Zinc ions were added by weight content to cement at concentrations of 0.2; 0.5 and 1.0 wt. %. The development of properties depending on the content of zinc ions and the type of compound used was monitored in this work. The measured values were compared with reference values that did not contain zinc ions. The highest compressive strengths were obtained with a sample containing 1.0% Zn in the form of zinc oxide. However, this sample is associated with a longer setting time due to the retarding effect of zinc ions on hydration. The retardation effect was monitored using isothermal calorimetry. For samples containing zinc ions, a negative effect on the brass layer of steel fibers, which was used as reinforcement, was observed. Due to the addition of zinc ions, dezincification and subsequent removal of brass from the surface of the fibers took place. Therefore, these specimens had lower tensile strengths. A positive effect on the differential ballistic protection efficiency factor was observed for a sample containing 1% Zn in the form of zinc oxide.
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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.
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Vliv teploty lepidla a povrchu adherendu na hloubku penetrace lepidla do masivního dřeva
Voldřichová, Anna
The final thesis deals with the influence of different gluing conditions on the depth of penetration of the adhesive into the surface of solid wood, specifically of the influence of increased pressure during pressing. Furthermore, the thesis investigates the effect of penetration on the strength of the glued joint under tensile loading. Specimens of spruce and oak wood were glued with UF glue and PVAC glue, pressed under different compression pressures and then subjected to tensile test. SEM analysis on an electron microscope was used to evaluate the depth of penetration. The results of the investigation of the effect of ink on the strength of the bonded joint and the penetration depth of the adhesive into the material are also included. The ink was used in the adhesive mixtures for the purpose of colouring the bonded joint.
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Use of 3D printing technology in the automotive industry
Hyhlík, Pavel ; Šafl, Pavel (referee) ; Binar, Tomáš (advisor)
This thesis deals with 3D printing technology and its applicability to the automotive industry. It discusses the types of technology, the materials used for 3D printing, required software and the specific applications. One of the materials is selected and analyzed for its properties, after which spare parts are designed and manufactured from it. The thesis includes a case study looking at the economic viability of additive manufacturing for engineered parts.
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Pevnost lepeného spoje ve smyku materiálů na bázi dřeva v extrémních podmínkách
Hromádka, Petr
This thesis deals with the issue of adhesive joints under extreme conditions. The aim of this work is to determine influence of temperatures -30 °C, +23°C, +70 °C on maximal tensile strength of adhesive joint and to determine which adhesive has the best results when used on specific agglomerated materials. Manufactured samples (chipboard, chipboard press-veneered by spruce, fibreboard, beech plywood board) were used in process of solving the task. These samples were used in accordance with standard ČSN EN 205. Data were processed by software and evaluation was accomplished by using statistical methods. As a result of a detailed research the adhesives appropriate for use in extreme conditions on Earth were determined. Contribution of this work is clarification of the impact of exposure temperature, type of adhesive and interaction between temperature of exposure and type of adhesive. Based on obtained results appropriate type of adhesive for given temperature during maximal tensile stress can be recommended.
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Influencing the hydration of high-performance composites using zinc ions
Všetečka, Tomáš ; Hajzler, Jan (referee) ; Novotný, Radoslav (advisor)
The bachelor thesis is focused on the influence of hydration of high-performance cementitious composites, more specifically reactive powder composites. Zinc ions were supplied by the compounds of zinc oxide and zinc sulphate heptahydrate. Zinc ions were added by weight content to cement at concentrations of 0.2; 0.5 and 1.0 wt. %. The development of properties depending on the content of zinc ions and the type of compound used was monitored in this work. The measured values were compared with reference values that did not contain zinc ions. The highest compressive strengths were obtained with a sample containing 1.0% Zn in the form of zinc oxide. However, this sample is associated with a longer setting time due to the retarding effect of zinc ions on hydration. The retardation effect was monitored using isothermal calorimetry. For samples containing zinc ions, a negative effect on the brass layer of steel fibers, which was used as reinforcement, was observed. Due to the addition of zinc ions, dezincification and subsequent removal of brass from the surface of the fibers took place. Therefore, these specimens had lower tensile strengths. A positive effect on the differential ballistic protection efficiency factor was observed for a sample containing 1% Zn in the form of zinc oxide.
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Study of FRP for concrete reinforcement
Blahová, Aneta ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis aims to analyze bent FRP reinforcements. It describes the method of production of bent FRP reinforcement, examples of application of FRR reinforcement in structures and mentions aggressive influences influencing the durability of FRP reinforcement. Furthermore, an experiment is proposed to monitor changes in straight and bent FRP reinforcement stored in an aqueous environment at 20 °C and an alkaline environment at 20 °C and 40 °C. The output of the diploma thesis is the evaluation of changes in mechanical properties and durability. The condition of the FRP reinforcement is documented using optical and electron mocroscopy.
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Vliv modifikace na pevnost lepení buku
Šmíd, Pavel
This diploma thesis is focused on the influence of thermal modification on the strength of bonded joint in tension according to ČSN EN 205. For the purpose of this work was used beech wood. The thermal modification of the test samples was performed at temperatures of 160 °C, 180 °C and 200 °C. The selected bond strength adhesives were melamine-urea formaldehyde adhesives (MUF), phenol-resorcinol formaldehyde adhesives (PRF) and one-component polyurethane adhesives (PUR). In addition to the thermal modification the effect of plasma modification on bond strength is also determined. The test lamellas were plasma treated (DCSBD) prior to gluing and pressing. The result is the determination of the tensile strength of the bonded joint in all the above-mentioned modifications and comparation of the results.
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Pevnostní a ekonomické parametry strojově šitých švů v současné čalounické výrobě
Falátek, Adam
This thesis dealt with strength and economic parameters of machine-sewn seams in current upholstery production. It is focused on the determination of the tensile strength of the bound seams and the influence of the decorative seams and the various types of lining on it. In the economic part of the test, material and time consumption is measured. The result is the evaluation of the different types of seams and lining and taxation in connection with the consumption of time, materials and their cost.
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Relationship between tensile strength and hardness of aluminium alloys
Růžička, Martin ; Jetela, Václav (referee) ; Klement, Josef (advisor)
This thesis deals with relationship between tensile strength and hardness of aluminium alloys. The introduction provides an overview of aluminum aloys and their properties. In the following section there is an analysis of the processing of aluminum alloys. A large part is devoted to the course of precipitation hardening. The second part of the thesis contains a practical part, which describes the methodology of measuring hardness and tensile strength. The measurement process is described below. At the end, the measured data are processed into various graphs and their results are evaluated.
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