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Keywords: cement

Investigation of plasticizing additives based on polycarboxylate esters on the properties of concretes formed by 3D printing

https://doi.org/10.58224/2618-7183-2022-5-5-42-58
 42-58 p.
Abstract
The article studies the features of the use of plasticizing additives based on polycarboxylate ether in the technology of additive construction production (3D printing). Layer-by-layer extrusion was carried out on an AMT S-6044 3D printer. The normal density and setting time of the cement paste, the average density, plastic strength and dimensional stability of the concrete mixture, the compressive strength and flexural strength of concrete were studied. It is shown that plasticizing additives based on polycarboxylate esters in the considered concentrations are effective modifiers of rheotechnological and physical and mechanical properties of cement concrete mixtures used in 3D printing technology. The greatest increase in compressive and flexural strength with the introduction of the studied polycarboxylate plasticizers is observed at PC CEM I 42.5N: the introduction of 0.5% "MasterGlenium 430" leads to an increase in compressive and flexural strength by 49.3% and 31.6%; with the introduction of "MasterGlenium 115" – by 21.6% and 35%; with the introduction of "MasterGlenium 591" – by 49.8% and 41.7%, respectively. Of interest for further research is the development of complex organo-mineral additives of multifunctional action based on polycarboxylate plasticizers for concretes molded by additive manufacturing (3D printing).
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UTILIZATION OF GYPSUM-BEARING WASTES IN MATERIALS OF THE CONSTRUCTION INDUSTRY AND OTHER AREAS

https://doi.org/10.34031/2618-7183-2021-4-1-5-17
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 5-17 p.
Abstract
Rational environmental management is one of the priorities of the technological development of the Russian Federation and most countries of the world. Particularly important in this area is the work undertaken with previously generated and accumulated waste, a whole group of which is gypsum-bearing wastes (GBW), which includes by-products of various industries: phosphogypsum, borogypsum, chlorogypsum, ferrogypsum, citrogypsum, vitamin gypsum, etc. GBW features are similar compositions, prevalence, perennial volumes of stored reserves with stable dynamics of annual growth. This determines the relevance of research on the development of a unified methodology for converting GBW of various types into target products particularly for construction purposes, providing maximum energy efficiency and minimal generation of secondary waste. The starting point of the research is the monitoring of approaches developed by the scientific community which are presented in the article. It is shown that researchers are exploring several main areas of GBW conversion: components of Portland cement and clinker; single and multicomponent binders; direct raw materials for the production of building materials; and road construction. The latter two directions have the greatest potential capacity for the consumption of GBW. The general level of research on the issue is not exhaustive, but has the potential to improve on existing methods of processing and application and promote the search for new and more efficient methods.
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DEVELOPMENT OF RADIATION-PROOF CONCRETE COMPOSITIONS

https://doi.org/10.34031/2618-7183-2020-3-5-24-33
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 24-33 p.
Abstract
The article considers the possibility of using composite binders and magnetite as components of concrete with radiation-proof properties. The use of the developed concrete is possible not only when it is necessary to build nuclear power plants, but also to create bunkers or anti-radiation shelters. A special feature of con-cretes used for the protection and design of nuclear reactor cranes is their properties, which they must have. These properties include: low thermal conductivity, increased density, high temperature resistance, reduced values of the coefficient of thermal expansion, shrinkage and creep. Technogenic raw materials for the production of very heavy concrete are studied, the main physical and mechanical characteristics, the requirements that need to be considered in the selection of raw mix composition for protective concrete are analyzed. The paper presents a comparison of physical and mechanical characteristics, the advantages and disadvantages of introducing a binder of various types: cement, cement with a superlasticizer and a binder of low water consumption. It was found that the use of a low-water-consumption binder increases the physical and mechanical characteristics while reducing the consumption of cement in the raw material mix compared to traditional heavy concrete with cement.
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EFFICIENCY OF STABILIZERS OF VARIOUS COMPOSITION FOR STRENGTHENING THE SOIL WITH A MINERAL BINDER

https://doi.org/10.34031/2618-7183-2020-3-1-30-38
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 30-38 p.
Abstract
The depletion of natural deposits of traditional inert mineral raw materials (sand, gravel) used to create effective layers of the foundations of roads leads to the development and application of new technologies and alternative materials. One way to solve this problem is to use local raw materials. For the construction of the lower layer of the road basement local soils are often used. However, their use is associated with the development of a set of measures to increase their efficiency, such as stabilization (by the use of chemical additives) and/or strengthening (by the introduction of various types of binders). In this regard, the paper analyzes the physicomechanical characteristics of reinforced clay soils obtained by introduction of various types of stabilizing additives in the presence of an inorganic mineral binder of hydration hardening type - cement - taking into account the recommendations for the used additives. The object of research was the most common representative of clay soils of the Belgorod region – heavy dusty clay loam. As a result of the studies, the authors established the reasonability of the use of the additives in the presence of cement, the most effective compositions of the reinforced soil were identified, contributing to the improvement of its controlled physical and mechanical characteristics. In addition, the need for additional studies to adjust the recommended composition of reinforced soil was established.
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INFLUENCE OF THE GENETIC FEATURES OF SOILS ON THE PROPERTIES OF SOIL-CONCRETES ON THEIR BASIS

https://doi.org/10.34031/2618-7183-2018-1-1-69-77
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 69-77 p.
Abstract
In order to form strong soil-concrete structures in parallel with the introduction of binder, an additive with a multicomponent composition that is activating the structure-forming process should be applied. Such addi-tive is usually called stabilizer of soil, its introduction allows achieving a positive effect for soils with a high proportion of finely dispersed fraction in its composition.
The article considers the main aspects of use in road construction of complex soil reinforcement by introducing a stabilizer and binding component. This technology will solve the problems of deficiency of high-quality traditional raw materials, lead to better physical and mechanical properties, increase labor productivity and reduce production costs.
As a result of the carried out studies, principles for improving the quality characteristics of reinforced soil were developed, taking into account the mineral composition of clay raw materials. As the main hypothesis of the study an increase in the hydrophobicity of stabilized soil by blocking the hydrophilic centers of clay rocks should be marked. This circumstance helps to reduce the consumption of cement in the reinforced soil without reducing the operational and physical-mechanical characteristics.
The dependence of the degree of effectiveness of the introduced stabilizing additive on the structural and chemical characteristics of clay rocks has been established, which decreases from montmorillonite and X-ray amorphous phases to kaolinite. Mixed layered formations, illite and chlorite act as intermediate minerals. Aluminosilicates act as the filler in this system that do not come into contact with the molecules of the stabilizer. To assess the degree of efficiency of interaction of the components of a soil-concrete mixture as an integral indicator it is necessary to use the cationic capacity of the soil.
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