The influence of lithium carbonate on the heat release during the hydration of Portland cement at the temperature 40°C

This work represents the stage of the author's research aimed at identifying the solutions for increasing the energy efficiency of the production of precast concrete and reinforced concrete products and structures in plant conditions due to reducing the temperature of heat treatment, or due to the reduction of duration of this technological process. The work provides results of the research of the influence of the admixture of lithium carbonate (Li2CO3) on the dynamics of hydration process of the binding systems on a cement basis in the conditions of the increased temperature (40°C). The research was performed using the method of isothermal calorimetry on the two various samples of the cement binder, conducted in various countries. The Li2CO3 admixture is accepted in dosages from 0.5% to 2.5%. The graphical dependence of the heat flow of the exothermic reaction of hydration on the used lithium carbonate dosage in the first days of curing of the samples is established and presented

Reactive powder concrete based on multicomponent cement systems with multilevel optimization of the disperse composition

This paper study the process of multilevel optimization of particulate structure of concrete. The improvement of performance characteristics of concrete can be achieved with a minimum binder content. Theoretical and experimental principles for the design of an optimal structure of concrete with an increased concentration of solid phase and operational characteristics, with a complex organo-mineral additive are developed on the basis of a rational proportion of chemical and finely dispersed mineral components. The high density of the structure is achieved by obtaining the dense packages by applying strong particles and grains with high elastic modulus and optimal parameters (dispersion and content) for each structural level. It is shown that it is expedient to use several structural levels of the particles of the clinker phase, and pozzolanization of the matrix must be carried out in accordance with the optimal formulation. Finely-dispersed slag, microsilica and highly dispersed fraction of cement were considered as mineral components, and superplasticizer of polycarboxylate type was used as a chemical additive

Mortars prepared with mechanochemical treated asbestos-containing waste

The paper presents the results of recycling of asbestos-containing waste (ACW). It is shown that hydraulic activity of ACW is increased using mechanochemical treatment in the vibratory ball mill in presence of anionic surfactant. Experimental results show that substitution of 10% w.t. of cement on activated asbestos-containing waste leads to increasing of the compressive strength to 20%. Finally, the effect of the activated ACW on the hardening kinetics of mortars is examined

Mortars prepared with mechanochemical treated asbestos-containing waste

The paper presents the results of recycling of asbestos-containing waste (ACW). It is shown that hydraulic activity of ACW is increased using mechanochemical treatment in the vibratory ball mill in presence of anionic surfactant. Experimental results show that substitution of 10% w.t. of cement on activated asbestos-containing waste leads to increasing of the compressive strength to 20%. Finally, the effect of the activated ACW on the hardening kinetics of mortars is examined

Optimization of the technology for the production of foam glass aggregate

The article presents the results of a study of the state of production of a foam glass and the nomencla-ture of its products. It is shown that it is expedient to use the recycled glass obtained from the bottle battle, the defective glass and the double-glazed windows as a raw material for the production of the foam-glass. The re-quirements are formulated for glasses, which should have low viscosity values in the range of foaming tempera-tures. The features of the technology for the production of the foam glass aggregate at the specialized lines are outlined. The technology features are the composition of the charge and temperature conditions of burning. The mixture for the production of the foam glass aggregate consists of glass flour, organomineral blowing agent con-taining water and food glycerin, as distinct from the slab foam glass, where soot or coke is used as a blowing agent. The results confirm the effectiveness of the use of the foam glass aggregate as a soundproofing backfill for floors. Currently, about 70% of the foam glass aggregate is used for roofs and stylobates; the rest is used in landscape design, road construction, foundations and major repair. In the future, the areas of application of the foam glass aggregate can be significantly expanded in the direction of building systems, lightweight aggregates, etc., which involves in-depth studies of the properties of this material

The influence of Li

Abstract. The present work was done during the research carried out by the authors, the aim of which was to develop methods for reducing energy costs in the manufacture of precast concrete and reinforced concrete structures for civil engineering. The paper presents the results of the analysis of the addition of lithium carbonate (Li2CO3) effect on the rate of hydration of Portland cement and the concrete obtained on its basis under high temperature conditions (80°C). The heat release curves were obtained during the hydration of samples based on a cement binder using the isothermal calorimetry method. The addition of Li2CO3 was taken in dosages from 0.5% to 2.0% by weight of cement. The graphical dependences of the heat release of the exothermic hydration reaction from the used dosage of lithium carbonate in the first 10 hours of hardening are established and presented in the paper. The obtained heat release data were compared with the graphs of the hardening of the samples tested by the standard method

Composition and rheological characteristics of plaster mixtures

The applying of local building materials is an effective contribution to the savings of mineral resources, which are used for the production of basic building materials. Clay and gypsum compositions are the local raw materials in many regions of the country and some neighboring countries. The article discusses the method for determining the clay fraction in the clay and gypsum composition, as well as the method for assessing the rheological characteristics of the plaster mixtures for interior work based on clay and gypsum binder. It was established that the content of the clay fraction in the studied clay and gypsum composition is in the range of 30–32%. Plaster mixtures based on clay and gypsum binder can be considered as optimal compositions under the following conditions. The grade of mobility is not less than PK3 (8–12 cm) in cone penetration test, the ultimate shear stresses in the first seconds of the thixotropic hardening ensure no runoff for the adjusted thickness of the applied layer. With the mentioned mobility, the “creeping” on the concrete surface is 10% and less, and the “creeping” on the brick surface is no more than 5%. The allowable water-solid ratio is 0,46–0,50