|
| |
|
|
Blast furnace slag as a component of hydraulic binders
Velebný, Josef ; Faltus, Miloš (advisor) ; Kuchařová, Aneta (referee)
The aim of this work is to evaluate blast furnace slag as an additive in hydraulic binders. These additives favorably affect the mechanical, chemical and phase properties of cements and binders on their basis. Basic structural and chemical analyzes of studied slags and reference cement and structural analyzes of hydrated binders were carried out on their basis. Furthermore, this thesis deals with testing and comparison of mechanical properties of mortar test bodies based on Reference Portland cement itself and with the addition of finely ground granulated and air cooled blast furnace slag and the development of these properties over time. Subsequently, these results are compared and made out about the usability of the studied materials for the production of hydraulic binders as compared to cements without added slag depending on time. Testing of mechanical properties according to the relevant standard ČSN EN 12390. Attention is paid mainly to the development of compressive strength and flexural tension. The XRD and XRF methods were used to study the phase and chemical composition of studied materials and hydrated binders based on these. Keywords: Slag, portland slime, hydraulic binder, Portland cement, blast furnace slag, phase composition, glass phase, latent hydraulicity, pozolanita, alkaline...
|
|
|
Hybrid systems based on alkali activated materials and Portland cement
Bradová, Lada ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
The most promising route to improve the sustainability of cement is to produce the blended Portland cements with supplementary cementitious materials. Blast furnace slag (BFS) is one of the significant pozzolan source used worldwide in blended cements contributing to lowering of the environmental impact of cement industry. On the other hand, the replacement of the Portland clinker is connected with the undesirable effects such as reduction of early strength development. In order to overcome this disadvantage, the study deals with the development of hybrid cements in which the utilization of solid waste alkaline activator quickly awakens the pozzolanic properties of BFS. The new types of blended alkali activated cements were designed to meet the European standard EN 197 1 and classified to the Blastfurnace CEM III/C cements in accordance with the mechanical, physical, chemical and durability requirements. The effect of alkali activation caused an increase in early (2 days) compressive strength development in comparison with reference sample. The setting time was delayed two times which is also interesting from the point of view of concrete production. Moreover, this non traditional hybrid alkali activated Portland cement provides considerable ecologically and economically potential.
|
|
|
The study of sulfate depletion in cement binders
Jurko, Michal ; Švec, Jiří (referee) ; Novotný, Radoslav (advisor)
This bachelor thesis deals with the study of sulfate depletion in cement binders. Basic knowledge about cement binders is summarised at the beginning of the theoretical part. The theoretical part goes on to describe the hydration of Portland cement (PC) and to briefly describe the influence of different types of milling on PC particle size. In the experimental part, PC fractions of various average particle sizes were prepared on a planetary ball mill for wet conditions. On the prepared cement, their hydration was studied using isothermal calorimetry; especially sulfate depletion, portlandite precipitation, heat flow rate and induction period interval. n the thesis were also used analyzes for autogenous shrinkage, XRD and STA. The input raw materials are cement CEM I 42,5 R (grey, Českomoravský cement, a.s. – Mokrá, Czech Republic) and sulfate-resistant cement CEM I 52,5 R (white, Aalborg Portland, a.s. – Aalborg, Denmark). On the basis of the results analysis, a proposal was made to correct the presence of sulfate ions by adding gypsum in these cements. In the case of CEM I 52,5 R the correction is recommended and in the case of CEM I 42,5 R the correction is necessary.
|
|
|
Characterization of portland cement hydration products by thermal dilatometric analysis
Dvořáková, Tereza ; Švec, Jiří (referee) ; Šoukal, František (advisor)
The paper presents the results of thermal dilatometric analysis of cement pastes during the heating at high temperatures. Volume changes were observed in samples of cement paste at selected time intervals during the hydration. Based on the measured data the dTDAc urves course has been described and the results have been compared with the curves of differential thermal analysis. To characterize the microstructure of the cement paste during the considerable shrinkage at higher temperatures the images by scanning electron microscope have been acquired.
|
|
|
Study of the properties of the ettringite which was produced synthetically
Hučínová, Lenka ; Jiroušková, Kateřina (referee) ; Fridrichová, Marcela (advisor)
Up to present, ettrigite has been prepared by two means in the Institute of Technology of Building Materials and Components of the BUT Faculty of Civil Engineering: originally by the hydration of the yeelimite clinker; recently by the direct synthesis of ettringite from calcium hydroxide and aluminum sulfate, the latter being considered more suitable in qualitative and quantitative terms. This diploma thesis focuses on the comparison of both means, using ettringite produced by the latter as control sample. This endeavor focuses on monitoring the stability of ettringite and its possible conversion to other minerals using X-ray diffraction analysis, thermal analysis and scanning electron microscopy (SEM).
|
|
| |
|
|
Synthetic Preparation and Properties of Thaumasite
Klásková, Silvie ; Dvořák, Karel (referee) ; Fridrichová, Marcela (advisor)
This thesis continues in the monitoring of thaumasite thermodynamic stability. It mainly deals with mineral properties and possible ways of its synthetic preparation. Mineralogical composition determined using X-ray diffraction analysis as well as possible impact of sample storage conditions can help further property identification. Based on the obtained radiographs, thaumasite mineral can be well distinguished from the very similar ettringite mineral.
|
|
| |
|
|
Thin-layer mortar mixtures
Ďurtová, Aneta ; Gazdič, Dominik (referee) ; Fridrichová, Marcela (advisor)
The bachelor thesis focuses on the development and properties of singlelayer or thin-layer reliefs formed by the partial substitution of binder components of waste materials, Portland cement and lime hydrate. For the proposed mixtures that have been prepared in the laboratory, they have been verified by the standard of prescribed properties.
|
guest ::
