Radek Magrla

Testing Self-Levelling Floor Screeds on the Basis of Ternary Binder

The work deals with processing and testing self-levelling floor screeds on the basis of ternary binder system of Portland cement - aluminous cement gypsum, to meet the target of ettringite development.

Monitoring of Calcium Sulphate Phase Transformations Using High-Temperature X-Ray Diffraction

Within the task the so called high-temperature X-ray diffraction analysis (HT-XRD) was used in the field of sulphated binders. Gypsum or calcium sulphate CaSO4.2H2O is the basic raw material for the sulphated binder production. As it is known by gradual warming of gypsum its different phase transformations can be obtained which significantly differ in its properties. Using this analysis identifications of temperatures of particular phase transformations in the CaSO4·xH2O system can be performed.

Study of Ettringite by Hydration of Yeelimite Clinker

This article describes the results of experimental works, dealing with long-term observing of ettringite stability (Ca6Al2(SO4)3(OH)12·26H2O). Thermodynamic stability of this mineral is important in terms of potential use of fluidized bed combustion (FBC) ash as an additive to Portland cement. Within the experimental work it was carried out observing of the ettringite formation by hydration of yeelimitu (Ca4Al6(SO4)·O12) in laboratory conditions. For the preparation of yeelimite it was proposed a three-component raw material mixture, consisting of a high percent limestone and gypsum and corundum. This mixture was subsequently placed in platinum crucibles and burnt in superkanthal kiln at 1200 °C. Formed clinker was mixed in chosen ratio with water and it was prepared a set of testing samples. These samples were exposed in the laboratory environment for up to 180 days. The hydration of the clinker was carried out using X-ray diffraction analysis (XRD) by determining the mineralogical composition.

Belit Cement Based on Concrete Recyclate

Main phase of belite cement is β-C2S. This modification is distinguished by low hydration speed compared to alite, which is main mineral of commonly produced cement. It is possible to increase the low hydration speed by modification of raw mixture by potassic ions, which basically change the belite structure. It leads to the content increase of internal free energy and therefore its reactivity too. Positioning of potassic ions in produced clinker is solved by combined burning.

Synthesis of Ettringite

The exposure of cement to high concentration of sulphate anions for a prolonged time period can lead to the formation of secondary ettringite and thaumasite. The preparation of synthetic ettringite is described in this paper.

Proposal and Testing Masonry Cement

This work deals with proposal and testing of cement mixtures normative called as Bricking cement. The norm demanded properties were tested on these cement mixtures depending on amount and type of used chemical admixtures. Technically it is possible to define this mixture binder as premix binder for ambulatory preparation of mortar and plaster admixtures.

Reduction of CO2 Emissions at Firing of Binders Type Portland Cement

Presented article deals with burn of raw admixtures with low content of carbon component for Portland cement burn. Fluidized ash is used as substitution of carbon component. At burnt model cements there are tested basic technological properties and it is observed hydrating process.