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Study of the effect of selected types of aditives on the properties of cement composites
Kavka, Lukáš ; Ťažký, Tomáš (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis describes admixtures for concrete. It deals with the influence of admixtures on the properties of cement composites in the fresh and hardened state. The theoretical part described the individual components of concrete, where the main attention was focused to inert admixtures and their effect on mechanical properties, shrinkage, resistance of cement composites to aggressive medium. Furthermore, the effect of admixtures on concretes with recycled aggregates was described. In the first stage of the practical part, cement mortars with 25, 35 and 50% replacement of cement admixtures were created. In the second stage, concretes with admixtures and a minimum strength class of C30/37 and C50/60 were created. Finely ground granulated slag, micronized limestone and granite stone dust were used as admixtures in mortars and concretes. The change of properties in the fresh and hardened state was observed on cement composites.
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Study of possibilities of reduction of volume changes and development of hydration temperatures in concrete
Pikna, Ondřej ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
Volume changes are one of the priority characteristics of concrete that plays an important role place mainly in the durability of structures as such. These low volume changes are required especially for structures as: industrial concrete floors, massive structures and waterproof structures. One of the possibilities in reducing these changes is the use of mineral admixtures with suitable grain curve of aggregate. Another possibility is the use of shrinkage reducing admixtures. There can occur problem with efficiency (long term age) with other components of the mixture. Therefore, the effort of this work is to use the avaible processes for maximum reduction of shrinkage and hydration temperatures.
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Research on the Preparation of Masonry Mortars
Koláček, Tomáš ; Dvořák, Karel (referee) ; Gazdič, Dominik (advisor)
This thesis deals with development in the preparation of masonry mortars. The theoretical part focuses on basic knowledge of mortars, individual types of mortar, preparation methods and individual components from which the mortar is composed. The practical part deals with the proposed reference and modified mortar mixtures and compares their technological properties.
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Reactive Powder Concrete
Gabko, Miroslav ; Klečka,, Tomáš (referee) ; Hela, Rudolf (advisor)
Reactive powder composites (RPC) have been recently a subject of many researches of modern concrete technology. This type of concrete is very fine and its behaviour exceeds the other types of concrete, therefore there are new possibilities of its use. The design and production of RPC is complex technology process which needs to gain new results in RPC research to get the best features regarding its higher price. This thesis is focused on design of reactive powder concrete (RPC200), which compressive strength is between 200 – 300 MPa. Next goal is to prove the influence of curing regimes like high temperature or pressure, and also check the possibilities of production of low cement reactive powder composite (LCRPC).
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Studying the possibility of improving the frost resistance of concrete
Šafrata, Pavel ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The purpose of this study is to summarize theoretical and practical knowledge of frost resistance of concrete. It suggests, that there are numerous factors affecting the freeze-thaw resistence of concrete. These are especially raw materials, production technology, time and method of curing. The influence of addition, air entrainment and air void structure is complied and evaluated experimentally. The testing method is crucial for the evaluation of durability of concrete. Hence, this thesis includes a research of methods used around the world and practical comparison of some of them. This thesis is valuable because of implementation of the requirement in the standard ČSN EN 206 (2014) for the frost resistence of concrete in exposure classes XF1 and XF3.
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Dispersed reinforcement influence on the maturation of polymercement materials
Zaťko, Petr ; Jakubík, Aleš (referee) ; Bydžovský, Jiří (advisor)
The diploma thesis is focused on polymercement materials with dispersed reinforcement. The aim of this work is development of suitable polymercement mixture and monitoring of the impact of dispersed reinforcement on the course of maturation of these materials and physico-mechanical properties. The effect of high temperatures on the properties of the mortar is also examined. Emphasis is placed on the use of alternative resources and byproducts. Mixed binder of cement and slag and admixture of microsilica was used. Recycled cellulose was used as dispersed reinforcement and was compared with commercial polypropylene fibers.
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