Key Engineering Materials Vol. 887

Abstract: Self-levelling and self-consolidating concrete mixtures formed with the use of superplasticizers are worthwhile for the manufacture of reinforced concrete structures. It is important to evenly distribute not only the mixing water in the system, but also the dissociated plasticizer ions for cement dispersed compositions with plasticizing additives. It is established that the optimal sequence of loading and mixing of the components of a cement composition is not only a promising direction for intensifying the manufacture of concrete building structures, but also a tool for improving the mechanical properties of cement brick and concrete made on its basis, as well as for increasing its durability and reliability. When superplasticizers are introduced into the pre-ground cement paste, the rheological properties of the compositions are improved, as well as the structure of the hardened composites. The given article is devoted to the study of the effect of the procedural factor and the duration of mixing of highly concentrated cement compositions with the addition of a superplasticizer based on naphthalene sulfonic acid (SP C-3) on the phase composition of hardened composites during various periods of hydration. Experimental results were obtained using the X-ray phase analysis method. Tested are 15 series of samples of cement stone with W/C ratio range between 0,18 and 0,27 and SP C-3 between 0 and 1.0 % by cement weight. Comparing the phase composition of cement stone after 28 days of hardening with that of 4,5 years, it was found that at first the C₃SH₂ phase, particularly enriched with calcium oxide, is formed, which decays over time and disappears in the 4,5-year hardening amples.

Abstract: Many plant wastes are not currently used in production, they are disposed of in landfills or incinerated. The aim of this study is to develop a composite thermal insulation material from unused spinning waste of flax and cotton fibers and soft wood waste. Samples of thermal insulation materials from plant waste were made by drying using the technology of production of soft wood fiber boards. For composite board defined physico-mechanical characteristics and thermal conductivity. The experiment was carried out according to a second-order plan, regression models of the dependences of the material indicators on the proportion of the binder additive, drying temperature and the proportion of wood waste additives were developed. The study showed that composites from unused spinning waste of plant fibers and soft wood waste have the necessary strength under static bending, the swelling in thickness after staying in water is much lower in comparison with the performance of boards from other plant fillers. The coefficient of thermal conductivity of the boards is comparable with the indicator for mineral wool boards.

Abstract: A technology has been developed for the processing recycling of waste - sulfuric cake into building materials with high physical and mechanical characteristics. Sulfur activator (zinc chloride) contributed to the chemical bonding of the components.

Abstract: The increase of thermo-physical properties of masonry made of ceramic burnt products is possible through the use of heat-efficient ceramics and, in particular, porous building tiles. The use of combustible additives or foaming technology is related to increased energy costs and difficulties in obtaining products with uniformly distributed porosity.The analysis of the state of the technology of ceramic materials made it possible to formulate a research hypothesis according to which the use of a porous non-combustible additive in the composition of ceramic masses, on the one hand, will make it possible to obtain materials with a lower density compared to traditional ceramic products, and, on the other hand, will allow the use of hard mixtures with reduced water content, and therefore significantly save the cost of drying products, while increasing the uniformity of the porous ceramic crock.The purpose of the research was to develop recipes for ceramic porous products and to develop modes of their burning. The use of crushed foam glass as a lightweight non-burning and exhausting additive, on the one hand, made it possible to use tough ceramic mixtures (with a water content not exceeding 18%), and, on the other hand, to use more rigid and shorter drying modes, which also reduced the energy and material consumption of the technology.The most energy-intensive burning process was optimized by the methods of mathematical planning and processing of experimental results. The average density of crushed foam glass (140–150 kg/m³), optimal for the burnt product, was established, and also, as a result of analytical optimization and interpretation of the experimental results, dependencies that allow choosing parameters and evaluating product properties depending on foam glass consumption and burning temperature were obtained.

Abstract: The paper presents the results of analyzing the prospects of using clay raw materials in a composition with metallurgical slags for the production of ceramic products. The results of the analysis of the chemical and mineralogical properties of clay from the Khalilovsky deposit in the Orenburg region and nickel slags from the dumps of the South Ural Nickel Combine are presented. The studies were carried out using X-ray fluorescence and differential thermal analysis methods. The article presents the performed X-ray and derivatograms of slag and clay and the features of the experimental types of raw materials revealed during their analysis. The connection between the chemical and mineralogical compositions of the experimental clay and slags on the technological properties of finished ceramic products has been theoretically established. The use of XRF and DTA to study the characteristics of plastic and non-plastic raw materials made it possible at the first stages of the experiment to reject materials that were unsatisfactory in properties for the production of ceramic products, which contributes to the optimization of experiments, rational consumption of costs of newly mined clay raw materials.

Abstract: The paper presents the studies on the compositions selection and properties of polymer-bitumen binders obtained using the viscous petroleum bitumen, styrene-butadiene-styrene polymer and plasticizer according to the experimental planning method. Regression equations of the polymer-bitumen binders processing and performance properties, which make it possible to optimize the compositions and predict their properties taking into account the operating conditions, were obtained. Polymer-bitumen binders in comparison with the properties of viscous road bitumen have the increased indicators of heat resistance, crack toughness, ductility and elasticity. To obtain the adequate mathematical model, the experimental data were processed, compositions were optimized and dependence diagrams were constructed by using the Maple software package. The software for a personal computer including the algorithm and program for selecting the polymer-bitumen binders has been developed. When using the software it is possible to automate the calculation of the polymer-bitumen binders compositions with a given set of technical properties.

Abstract: Creating waste-free technologies for the production of materials with high physical and thermal properties for the lining structures of thermal units is among the important environmental issues. Studies have shown that the waste of processing copper-zinc concentrates – ferrite-calcium slag crushed to pass through a sieve No. 0063 (the sieve residue is 1.2 % max.) can be used as a finely ground component of an iron phosphate binder. Studies have shown that under normal curing conditions at one-day age, refractory concretes based on an iron phosphate binder acquire strength sufficient for stripping, transportation, and installation of structures. At 7-day age, they acquire final strength, the value of which is determined by the aggregate properties. The iron phosphate binder refractoriness is 1,300 °C, and the working temperature of the concrete lining using expanded clay as coarse aggregate is 1,000 °C.

Abstract: The modern construction industry is more and more inclined to use composite binders instead of traditional binders. Composite binder is characterized by increased efficiency and environmental friendliness, improved performance characteristics at a reduced cost and energy consumption. Based on this, studies are needed to determine the possibility of using quartz-feldspar sand as a component of composite binders.

Abstract: The article is devoted to the problem of raw material base expanding and improving construction and technical properties of porous granular materials. The results of experimental studies of silicate compositions based on liquid glass and technogenic fillers containing burnable or gas-forming components are presented. Influence of molding mixtures’ composition on thermal expansion nature of granular compositions was established. Preference of a filler combined, containing glass cullet, silica clay and mineral additives was revealed. Multicomponent composition of a filler helps to intensify composition’s expansion. Electron microscopy studies of porous silicate granules have confirmed the advantages of combined fillers using. Effectiveness of sodium additive introduction to regulate technological properties of the raw material and the process of pores formation has been proven. Expediency of mechanical activation of a raw mixture to reduce the temperature of expansion and obtain granules with a bulk density of not more than 300 kg/m³ has been determined.

Abstract: The article analyses the influence of SiO₂ and Al₂O₃ nanopowders on properties of ceramics consisting of fly ash from thermal power plants, glass waste, and clay binder. Based on studies of physical and mechanical properties of the obtained ceramics (ultimate compressive strength, ultimate three-point bending strength, wear resistance, and water absorption), the paper shows the positive influence of the nanoadditives. The optimal number of SiO₂ and Al₂O₃ nanopowders in the formulation is 0.5 wt. % that has the strongest effect on ultimate compressive strength and water absorption of the fly ash ceramics samples. The direction of further research on improving the properties of ceramic products is an application of the Al₂O₃ nanopowder as more perspective nanoadditive using clay dispersant.