Nowadays, in industrial production, lithium consumption is strongly increasing and it can be assumed that waste material with an increased content of this metal could also appear. One of the most important sectors where different types of waste can be utilized is the cement industry. Therefore, it is desirable to monitor the influence of lithium on formation and properties of the clinker. In the presented work, this effect was monitored in laboratory conditions up to 5 wt.% Li2O. X-ray diffraction, DTA and optical microscopy were employed as research methods. Among other things, it has been found that Li2O causes the decomposition of the alite, the major clinker phase, to a microcrystalline mixture of belite and free lime, depending on its content and clinker cooling rate.

Implementation of high belite cement in cement production would have strong environmental impact in reduction CO2 emissions and saving of pure limestone deposits. The goal of the study is to describe the role of alkali and C-S-H activators on hydration of high belite cement. Analytical approach for early hydration is based on combination of isothermal calorimetry, X-ray powder diffraction in-situ, DTA-TG, FT-IR.

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This paper deals with hydrothermal stability of inorganic aluminosilicate polymers, which were prepared by mixing blast furnace slag, fly ash and cement kiln dust in ratio 4:2:1. Cement kiln dust was used as alkaline activator with 4M sodium hydroxide solution. Samples were cured under hydrothermal conditions up to 170 °C for 24h and changes in mechanical properties, phase composition and porosity were monitored. During the hydrothermal process, the formation of zeolite from cancrinite group was monitored. The effect of the change of composition on the thermal expansion/shrinkage was studied by thermal dilatometry. Autoclaved samples were subjected to significant irreversible shrinkage during heating to 900 °C.

Production of low-energy cements would result in energy saving and lower CO 2 emissions related to reduced consumption of fuel and high-grade limestone as a raw material. Belite rich clinker, made more reactive by doping with combination of S and Li, could possibly be one of the low-energy alternatives for Portland cement clinker. Paper describes the preparation of doped belite and deals with its early hydration and reactivity. Belite rich clinkers were prepared in laboratory in high-temperature solid state synthesis. Pure substances were used for the preparation of raw meal and clinker. Early hydration heat flow development of cement pastes was monitored by isothermal calorimetry, changes in phase composition by "in situ" X-ray diffraction and TGA/DTA and microstructure by SEM-SE. Heat flow exotherms were correlated with quantified phase composition at given time. Intensity and position of main exothermic peak related to hydration of C 3 S is changing with increasing Li content. Doping of the C 2 S by the S or the combination of S and Li significantly increases the reactivity of the C 2 S-rich cement. The formation of C-S-H products is a continuous process that depends mainly on C 3 S during first 6 h and then is supported by slow reaction of β-C 2 S. The reactivity of C 2 S is affected by the timing of the hydration of other clinker phases. Two generations of portlandite formation detectable as a double endotherm on TGA/DTA can be attributed to hydration of C 3 S and β-C 2 S.

Limestone is a suitable substitute for economically less favourable Portland clinker in Portland blended cements. Limestone in cement not only serves as a very fine filler, but can also act as a reaction component. In this work, the properties of laboratory Portland cements with limestone were studied. The cements were prepared from two limestone types and two clinker types with a graded limestone content of up to 30 wt. %. The limestones had a different CaCO3 content. Clinkers were distinguished by a marked difference in C3A content and hydraulic activity. The effect of limestones on the technological properties of cements, the hydration process and the impact of separate and together grinding of limestone and clinker were studied. In this case, the type of clinker had stronger impact than the type of limestone on the technological parameters. It was also confirmed that a low limestone content has a positive effect on cement hydration.

Reactive belite cement based on clinker doped with sulfur is a new type of low-energy cement that is still in the laboratory testing phase. In terms of application, one of the desired properties of new cement is its well-defined rheological behavior in fresh state. The chemical composition of the belite cement was determined by wet chemistry analysis, the phase composition of the belite cement clinker by quantitative X-ray powder diffraction analysis and microscopic point counting and specific surface by Blaine method. Rheological properties were determined by rotational rheometer in flow and oscillation regime. Shear and time dependent rheological parameters were calculated from flow curves. Stability of belite cement paste was judged based on the critical strain determination in amplitude sweep test. Setting was evaluated by Tussenbrock needle penetration test and oscillation time test on rheometer. The properties of the laboratory belite cement were correlated to industrial cement CEM I, CEM II/A-LL and CEM III/A. Reactive belite cement pastes show good flow properties both due to small amount of alite and larger amount of rounded belite grains and clusters. Belite rich cement show decent stability comparable to CEM III and very good dispersing efficiency of PCE based HRWR.

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