INTENSIFY HEAT-RESISTANT BINDER BASED ON PORTLAND CEMENT

Aim. The article presents the results of a study of heat-resistant binder based on Portland cement with the addition of a local mill ground minerals.Methods. Activation is carried out on a planetary mill "Activator - 4M". Activation of the binder increases the strength of heat-resistant concrete by increasing the reactivity bundles "Portland is the active fine additive" to the mechano-chemical additive.Results. It is determined that the mill ground additives result in the formation of low-melting and thereby reduce the temperature of the use of heat-resistant concrete with Portland cement binder.Conclusion. It is proved that high mechanochemical strength refractory concrete samples on activated binder is caused by the process of increasing the chemical activity of the materials included in a bundle of "Portland cement is the active fine additive" which creates favorable conditions for hardening of heat-resistant concrete

THE INFLUENCE OF THE FILLER GRAIN COMPOSITION ON THE PROPERTIES OF THE HEAT-RESISTANT BASALTIC CONCRETE

Objectives. The optimal granulometric composition of filler compound ensures the production of concrete having improved  physical and mechanical characteristics, as well as minimal binder  consumption. The properties of heat-resistant concrete largely  depend on the type and the ratio of its components. Taking this into  account, the aim of the study is to determine the optimal grain composition of heat-resistant concrete.Methods. Methods for optimising the properties of heatresistant basaltic concrete with a composite binder and  mechanochemical activation of the filler grains were used during the  course of the research.A simplex-centroid experiment design is  applied for this purpose. The composite binder was subjected to  mechanochemical activation. Samples were made by vibration-pressing from a concrete mix with a cone draught of 2 cm.Results. The grain composition of heat-resistant concrete is proved  to be the most important variable factor, regulating which the  properties of concrete can be varied. The compositions of heat- resistant basaltic concrete with activated composite binder having a  maximum application temperature of 700 ºС are developed. The  influence of the grain composition of the basaltic filler on the  properties of basaltic concrete using mathematical experiment planning methods is determined. The regression equations for the ultimate tensile strength and bending stress of basaltic concrete are  obtained for heating temperature of 700ºC.Conclusion. The granulometric composition of heat-resistant basaltic concrete based on the activated binder is optimised for basic physical and technical properties. The optimal granulometric  design of the composition of heat-resistant concrete indicates that as the coarse fraction (particles greater than 0.63 mm) in the filler  composition increases, the ultimate tensile strength and bending  stress of heatresistant basaltic concrete is increased when heated to  a temperature of 700ºС. This is due to a more compact arrangement of sand grains

THE EFFECT OF PRELIMINARY ELECTRIC RADIO HEATING ON THE PHYSICAL AND THERMAL CHARACTERISTICS OF THE HEAT-RESISTANT CERAMZITONE-CONCRETE BASED ON COMPOSITIVE BINDER OF LOCAL MINERAL RAW MATERIALS

Objectives. The aim of the study is to increase the physico-thermal and operational characteristics of heat-resistant ceramsite concrete with an activated binder by pre-heating the mixture.Method. To conduct the study, a technique was developed by the Research Institute of Concrete and Reinforced Concrete named after A.A. Gvozdev.Results. An analysis of the study results of the effect of preliminary electric heating on the physico-thermal characteristics of heat-resistant ceramsite concrete on the basis of a composite binder showed that, in comparison with drying at a temperature of 105º, the operational properties of heat-resistant ceramsite concrete are enhanced by uniform heating of the samples along the concrete body. This isdue to the pore pressure in the concrete structure being reduced by removing physically bound water. Ceramsite is used as large filler while ceramsite sand is used as small filler; activated composite combination of local mineral raw materials consisting of Portland cement and calcined argillic clay is used as a binder. In the concrete body, due to the removal of physically bound water caused by the decrease in pore pressure, the formation of cracks in the interporal partitions decreases, preventing the explosive destruction of heat-resistant ceramsite concrete and improves its physico-mechanical, thermal and operational characteristics. Activated composite binder based on the combination of Portland cement and fine ground argillite clay reduces shrinkage deformations and increases the concrete strength as well as its heat resistance. Concretes with activated composite binder are less susceptible to volume change during the heating process,contributing to greater preservation of concrete strength and structure due to lower stress levels caused by the temperature deformations.Conclusion. The composition of the developed heat-resistant ceramsite concrete allows its use for monolithic lining of the walls of a tunnel kiln for burning ceramic bricks, as well as various concreting furnaces for the construction industry. The conducted research demonstrates the possibility and expediency of using electric heating for the hardening of heat-resistant ceramsite concrete with a composite binder. The use of electric heating increases the strength of heat-resistant ceramsite concrete both before and after heating to high temperatures. Optimised modes of electric heating of heat-resistant ceramsite concrete with a composite binder are established

EFFECT OF VACUM TREATMENT ON TECHNOLOGICAL PROPERTIES OF HEAT-RESISTANT CERAMZYT-CONCRETE ON COMPOSITIONAL BINDING

Objectives The aim of the study is to study the effect of vacuum treatment, heating temperature, mixing time and load force on the strength of heat-resistant expanded clay concrete for lining thermal units.Method The study is based on the vacuum processing technology of heat-resistant concrete based on a composite binder for lining the hearth of a trolley of a brick kiln, vacuum-packed concrete mix.Result The effect of vacuum processing of the mixture on the technological properties of heat-resistant expanded clay concrete on a composite binder made from Portland cement and finely ground expanded clay activated in a planetary mill (Activator-4M) is investigated. Compositions have been developed and the technological properties of expanded clay concrete have been investigated depending on the heating temperature and the amount of finely ground additives.Conclusion The results of the analysis of the dependence of the strength of expanded clay concrete on the heating temperature, the mixing time and the load strength confirm that the concrete strength indicators during evacuation are higher than for concrete without vacuum treatment; the increase in concrete strength after vacuum treatment under various technological exposure conditions is explained by an increase in workability indicators, which is characterized by the mobility and stiffness of the concrete mixture, denser packing of aggregate in the concrete structure, and also the large effect of vacuum compaction associated with the suction of water and air as well as static sealing due to the difference in atmospheric pressure and vacuum cavity pressure. The magnitude of the effective force reaches 70-75 kN / m2 with the removal of water and air from the vacuum surface; the pressure transmitted to the concrete is reduced, since part of the load is spent on determining the forces of internal friction and the development of contact stresses in the solid phase