Andrey Pustovgar

Pore Structure Formation of Modified Cement Systems Hardening over the Temperature Range from +22°C to -10°C

The article presents the research results of modifying antifreeze influence on the pore structure formation of dry mortars in terms of adhesive and base layers of external thermal insulation composite systems within different temperature regimes of hardening.

Concrete Waste Recycling and Re-use of Shielding Wall Materials After Decommissioning of Fusion Reactors

The paper considers possible processing and re-use of waste products obtained in the process of removal from service of pre-fabricated concrete structural elements of biological protection shields at thermonuclear fusion reactors. The experimental concrete compositions have been obtained through the mechanical-and-chemical processing of crushed concrete structures which had worked under neutron radiation with the energy of 14.8 MeV. These concrete compositions have been studied, and some ways of total or partial substitution of the Portland cement by crushed small-grain waste products in the process of erection of concrete or reinforced concrete structures are considered as well.

Technology for Hydrothermal Destruction of Organic Fuel Materials

The article presents the results of research of the hydrothermal destruction technology of organic fuel materials for the production of steam-flue gas mixture for thermal engines.

Research on the Effect of Prehydration of Portland Cement Stored in Normal Conditions

This article is a stage of the author’s research into the impact of different factors on the hydration of mineral binders. The problem of cement activity decrease due to adsorption moisture influence during long-term storage in normal conditions (20°C and 50% RH) was examined. The influence of storage period in airtight and non-airtight conditions on the kinetics of heat evolution during hydration as well as on phase composition of Portland cement was characterized using experimental methods.

Evaluation the Strength of Cement Systems, Modified by Accelerators

Nowadays, there is a great demand for the accelerated hardening construction mixtures. That causes the necessity to the methods development for testing the effectiveness of accelerators, well as the analysis of kinetics of cement systems hydration in the early stages of hardening. This paper presents the results of an experimental research of interrelation between the growth kinetics of cement-based binder system strength and the heat release for pure cement hydration. How it was found, two compositions of construction mix, which are identical in mineral composition and differ in the presence of mono-functional accelerator, a comparison of strength growth dynamics can be carried out indirectly via the integral curve of heat release, obtained using the method of isothermal calorimetry.

Special Aspects of Hydration Process of Microfine Cement

The aim of the present research was to determine special features of hydration process of two commercial microfine cements compared to CEM I 42.5N cement with similar mineralogical composition. The influence of cement fineness and composition on the hydration process was investigated by isothermal calorimetry of cement pastes and quantitative X-ray powder diffraction of hydration products at 1, 3, 7, 14 and 28 days.

Effect of Modifying Admixtures on the Cement System Hydration Kinetics

Presented are the results of the research on the impact of such factors as temperature conditions and cement phase composition on the effectiveness of hardening accelerators for concrete and other cement systems. The evaluation of the modifying elements effect has been performed by using the isothermal calorimetry method. This research revealed the selectivity of the admixtures impact when used together with different cement brands, as well as the possibility of increase setting time for cement systems in lower temperature conditions with the addition of Lithium carbonate based accelerator.

Influence of Chemical Additives on Radiation Stability of Concrete - Theoretical Basis and Evaluation Method

The influence of additives on the radiation stability of the concrete will occur through the influence of radiation changes of hardened cement paste on radiation changes of concrete and can be quite significant. The test sequence was produced according to the modified method described in case [11]. The samples were prepared in the form of prisms with the following dimensions: 10 mm x 10 mm, 30 mm. Measurement series were produced after each heating and cooling sequence. Then the difference between the values before and after heating was calculated.