No abstract

This work deals with the influence of zinc on cement hydration. The amount of zinc in cement has increased over recent years. This is mainly due to the utilization of solid waste and tires, which are widely used as a fuel in a rotary kiln. Zinc can also be introduced to cement through such secondary raw materials as slag, due to increased recycling of galvanized materials. The aim of this work was to determine the effect of zinc on the hydration of Portland cement, blended with ground blast furnace slag (GBFS). This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors the hydration process in real-life conditions, while isothermal calorimetry does so at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts, namely Zn(NO3)2, ZnCl2, and a poorly soluble compound, ZnO. The concentration of added zinc was chosen to be 0.05, 0.1, 0.5, and 1mass percent. The amount of GBFS replacement was 15% of cement dosage. The newly formed hydration products were identified by X-ray diffraction method (XRD).

No abstract

Possibilities of a multicell isoperibolic-semiadiabatic calorimeter application for the measurement of hydration heat and maximum temperature reached in mixtures of various compositions during their setting and early stages of hardening are presented. Measurements were aimed to determine the impact of selected components’ content on the course of ordinary Portland cement (OPC) hydration. The following components were selected for the determination of the hydration behaviour in mixtures: very finely ground granulated blast furnace slag (GBFS), silica fume (microsilica, SF), finely ground quartz sand (FGQ), and calcined bauxite (CB). A commercial polycarboxylate type superplasticizer was also added to the selected mixtures. All maximum temperatures measured for selected mineral components were lower than that reached for cement. The maximum temperature increased with the decreasing amount of components in the mixture for all components except for silica fume. For all components, except for CB, the values of total released heat were higher than those for pure Portland cement samples.

A multicell isoperibolic — semiadiabatic calorimeter was used for the measurement of temperature and the determination of the hydration heat evolution at earlier period of cement pastes setting and hardening. The measurements were aimed at the determination of the effect of superplasticizers (SPs) on the course of the Portland cement hydration. Commercial polycarboxylate SP was added to the mixtures and the heat effect was measured. With the increasing content of SP, the hydration temperature increased up to a certain value and then decreased. In case of a sufficient amount of water in the mixture to achieve complete hydration of cement, samples with the highest values of the maximum hydration temperature reached the highest values of the released total heat. If there is not a sufficient amount of water to achieve complete hydration, the samples with the highest values of the maximum hydration temperature reach the lowest values of the released total heat.

Abstract. The aim of this work is to show commonly used procedures and methods for limestone analysis. The samples were measured with Inductively Coupled Plasma with Optical Emission Spectrometry (ICP-OES) for chemical compositions determination. For these measurements, the samples were decomposed by dissolving in acid, melting into solution and decomposed by microwave. Due to the time and financial demands of these analyses, there were an effort how to find a satisfactory method providing sufficient results with less time and financial demands. The X-ray diffraction (XRD) method was first tested, followed by X-ray fluorescence (XRF). Samples were measured in powder and melted into pearls. The evaluation was carried out by using of the Fundamental parameters method and by means of instrument calibration. The method of combustion elemental analysis was selected to determine of the sulfur content. IntroductionThe limestone has been used by humans for several thousand years, and there still grow the possibilities of processing and using of this raw material. Limestone was formed mainly as sedimentary rocks. Most limestones originated in the seas and their genesis was associated with rockforming organisms. Limestones were also created in fresh waters, lakes, rivers and caves. The main conditions for the formation of limestone were the climate and the absence of clay or sandy material. Calcium carbonate has several polymorphic modifications. In nature, it is predominantly as minerals of calcite and aragonite. Calcite is usually sediment from organic origin. Aragonite secreted from solutions at higher temperatures or in the presence of sulfates. It may also have a biogenic origin from the shells of some molluscs [1].Limestones are rocks predominantly made by minerals of calcite (calcium carbonate with trigonal structure, CaCO3). They are solid and grained sedimentary rocks of organic or chemical origin. The calcium carbonate content is often above 95%. Most of the limestones were formed by the settling of limestone canals of animals and plants, mainly in the sedimentary basins of the sea. These limestones are called organogenic. In a small amount, limestones were excreted from aqueous solutions in karst lands. Conversion of limestones at high temperature and pressure resulted in crystalline limestones (marbles) in which calcite recrystallized so that the calcareous shells of animals did not appear in marble. Limes only rarely occur clean. Mostly they have admixtures of clay, carbonates, dolomite, sand, or phosphates or iron-containing minerals [1].

The amount of zinc in the clinker or in the secondary raw materials has been increasing in recent years mainly due to the processing of waste materials containing zinc. The aim of this work is to show the effect of zinc on hydration of Portland cement and mechanical properties. These effects were studied by isoperibol calorimetry and mechanical properties testing. Zinc was added to the cement in the form poorly soluble compound ZnO. The concentration of zinc added was chosen as 1wt. percent. The newly formed compounds during hydration were identified by X-ray diffraction method (XRD). Another objective is to show the effect of silica fume (microsilica, SF) as the secondary raw material and water to binder ratio on hydration of cement in the presence of zinc.

No abstract