ceramics, glass and enamels
ISSN 2076−0655
Volume 29
Any article from the issue, as well as the entire issue, can be purchased electronically
KEY WORDS:
frost resistance of concrete, low-modulus inclusions, polymeric microspheres, stress state of concrete, finite element method
Obtaining of concretes with increased durability is the topic of many modern scientific researches. One of the main parameters determining the durability of concrete is frost resistance. This characteristic can be increased by introducing air-entraining and expanding additives, microfillers with pozzolanic activity, components promoting self-healing of concrete and inclusions with low modulus of elasticity. In the experimental part, the effect of low-modulus inclusions, of which Expancel polymeric microspheres were used, on the frost resistance of concrete was evaluated. A fragment of concrete with a crack, the mouth of which was located on an inclusion or a void, was modeled using the finite-element method. The modulus of elasticity of the inclusion ranged from 30,000 MPa (equivalent to concrete) to 5 MPa (close to zero). According to the calculation results, the fields of normal stresses in the concrete structure under the action of the crack wedging load were obtained. On the basis of the analysis of the experimental results and literature sources, some conclusions about the influence of inclusions with a low elastic modulus on the frost resistance and the stress state of concrete have been made.
FOR CITATION: Panchenko A.I., Murashov A.O Influence of low-modulus inclusions on frost resistance of concrete // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 304 – 310.
KEY WORDS:
concrete hardening age, creep, shrinkage, crack resistance, relative humidity, analytical predictive model.
ABSTRACT:
A change in the relative humidity of the environment has a significant impact on the deformation processes occurring in concrete and reinforced concrete products and structures, aggravated by the action of operational loads. The moisture shrinkage gradient increases as the concrete dry out, resulting in shrinkage stresses in the structures of operated buildings and structures, which can lead to their cracking. Thus, the main reason for the formation of cracks in concrete structures during their operation is volumetric instability. Deformations that cause a change in the volume of concrete include drying shrinkage, autogenous shrinkage, and thermal expansion deformations. The paper presents the results of studies carried out to assess the influence of relative humidity of the environment on the creep and shrinkage of concrete at different hardening ages, carried out using the ACI 209R-92 analytical predictive model. Establishing the causes of the appearance of creep and shrinkage deformations in concrete structures is a necessary condition for combating the occurrence of cracks and extending their operational reliability.FOR CITATION: Trong Chuc Nguyen, Bulgakov B.I., Aleksandrova O.V. Influence of relative humidity on creep and shrinkage of concrete // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 311 – 316.
KEY WORDS:
Ultra-High Performance Concrete, UHPC, aggregate, quartz, quartzite, strength
ABSTRACT:
In both our country and abroad, ultra-high-strength concrete (Ultra-High-Performance Concrete, - UHPC) is becoming increasingly important for producing concrete and reinforced concrete structures. Due to their high strength characteristics and increased durability, such concretes are highly durable. Due to its high cost associated with its increased cement content and active and inert mineral additives, this material is not widely used. By reducing the content of the most expensive components - binder and active mineral additives - and increasing aggregate content, one of the ways to solve this problem can be achieved. The paper presents the results of determining the compressive, flexural, splitting tensile strength, as well as ultrasonic pulse velocity of ultra-high performance fine-grained concrete containing different amounts of quartz and quartzite aggregate. Concretes with compressive strength from 156 to 182 MPa and cement consumption from 1276 to 700 kg per 1 cubic meter were obtained, and the effect of the type and amount of aggregate on strength properties was also established.FOR CITATION: Soloviev V.G., Matiushin E.V., Veselov V.K. A study of the impact of aggregate type and volume content on the properties of ultra-high performance fine-grained concrete // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 317 – 325.
KEY WORDS:
modified concrete, dispersed composition of the clinker component, polydisperse binder.
ABSTRACT:
As part of these studies, issues related to the modification of the composition of heavy concrete with the use of a complex chemical additive consisting of the superplasticizer Melflux 5581 F and the water-soluble polymer additive Polidon-A together with micro-reinforcing basalt fiber are considered. The purpose of the study is to substantiate the possibility of obtaining effective heavy concrete for irrigation and drainage construction with improved indicators of operational properties in terms of strength and hydrophysical characteristics. The object of study is heavy concrete based on a polydisperse binder with a complex polymeric modifier for irrigation and drainage construction. Research results. The influence of the three-level dispersed composition of the clinker component of cement particles on the reduction of interparticle voidness and the increase in the strength of the cement stone was studied. The obtained modified concrete based on a polydisperse binder is characterized by an increase in compressive strength up to 59.68 MPa, tensile strength in bending 6.73 MPa and a decrease in water absorption up to 2.43% in comparison with the control composition. The obtained performance indicators give us the opportunity to recommend it for the production of building products and structures operating in harsh operating conditions, in particular, for irrigation system flumes.FOR CITATION: Tkach E.V., Filimonova YU.S. Modified heavy concrete based on polydisperse binder for hydromeliorative construction // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 326 – 334.
KEY WORDS:
radiation-protective materials, barite containing foamed concrete, finely ground barite containing additive, ionizing radiation
ABSTRACT:
In the modern concrete industry, to provide protection against ionizing radiation, as a rule, concrete designed with heavy aggregates are used. These materials have obvious disadvantages, such as the complexity of construction technology and high construction costs. In this study, it is proposed that cellular concrete based on barite mineral raw materials can be used for protection against ionizing radiation of low power. The object of the study is a composite cellular material based on Portland cement, finely ground barite additive, quartz sand and foam. Tensile and compressive strength of the material, its density and technological properties of the cement slurry were studied. 15 batches of prismatic beams with face sizes of 4 cm, 4 cm, 16 cm were prepared with different amounts of barite-containing additive, foam, and quartz sand. The compositions of the specimens were chosen in accordance with the three-factor central compositional plan, to form analytical models of the experiment based on the results. Experimental data confirmed that the higher amount of quartz sand and barite-containing additive increases compressive and tensile strength of the material, also an increase for foam leads to a decrease in these characteristics. The study of the viscosity of the mortar demonstrated that the introduction of a barite-containing additive reduces the viscosity of the mortar more than the quartz sand. The most promising compositions of foamed concrete for the construction of radiation protection structures have been determined.FOR CITATION: Samchenko S.V., Novikov N.V. Influence of a barite containing additive on the properties of cellular concrete // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 335 – 341.
biostable composite; plant raw materials, organopolymer binders, thermal conductivity, heat insulating material, strength, density
ABSTRACT:
The work is devoted to the creation of heat-insulating composite materials on the basis of modified vegetable raw materials and organopolymer binders. The aim of this work was to estimate the mechanical and thermo-physical properties of biostable composites based on chopped stems of Sosnovsky's hogweed, previously modified by monoethanolamine (N-B)-trihydroxyborate, and organopolymer binders (polyurethane (PU), polyvinyl acetate (PVA), and casein glue (KK). Determination of density was carried out in accordance with GOST 17177-94; tests of compressive and bending strength were also carried out in accordance with GOST 17177-94; and the thermal conductivity was evaluated according to GOST 7076-99 using an electronic thermal conductivity meter, the ITP-MG4. The research results show the creation of highly efficient heat insulation materials with low thermal conductivity and low density in accordance with the requirements of current standards. In addition, we obtained the values of compressive strength at 10% deformation and bending strength of the obtained composites, which significantly exceed the minimum values prescribed by the current standards. It should be noted that the use of a polyurethane binder allowed for the best composite properties to be obtained.
FOR CITATION: Sodomon М., Stepina I.V. Thermo-Physical Properties of Composite Materials on the Basis of Vegetable Raw Materials // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 342 – 349.
KEY WORDS:
heavy-weight concrete, ferruginous quartzite, iron ore, coarse aggregate, splitting strength
ABSTRACT:
Preparation of iron ore for its use in shotcrete must be based on a detailed study of the initial mineral raw materials, its mineral composition, physical properties, physical-mechanical properties. The choice of the scheme of ore preparation depends on the detailed analysis of all the features of the ore and taking into account its application. For the use of ore as an aggregate for shotcrete several requirements to the aggregate: crushability above D600, water absorption no higher than 2%, it is not recommended to use flaky aggregates by virtue of the increased percentage of ricochet by these types of aggregates. Just need to analyze the surface of the aggregate for its wettability and surface roughness to assess the possibility of obtaining high-quality shotcrete coating. The preparation of ores can be approached in several ways: mechanical, chemical, heat treatment, as well as there is a possibility to modify the concrete mixture taking into account the use of iron ore aggregate. In the case of using iron ore from Mikhailovsky ODP revealed an increase in strength of up to 30% due to adhesive bonds between aggregate and cement-sand mortar.
FOR CITATION: Soloviev V.G., Sizyakov I.D. Physical-mechanical properties of ferruginous quartzites and concrete based on them // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 350 – 358.
KEY WORDS:
self-compacting concrete, water consumption, water separation, Portland cement, blast furnace slag, microcalcite
ABSTRACT:
Fine particles of cement and microfillers occupy most of the total specific surface area, they have the strongest influence on the total water consumption of the concrete mixture. The most expedient is their lowest water consumption, the correct determination of which for self-compacting concrete is very important for covering all particles with a layer of water of a certain thickness. Therefore, the study of water consumption of fine materials used for self-compacting concrete (SCC) is an urgent task. The aim of this study was to investigate the water demand of the fine-dispersed components and to establish their suitability for obtaining SCC. The water consumption for each material was determined using a linear regression equation, which includes a water consumption coefficient KWc and a deformation coefficient Kd, which is the slope of the linear function or the degree of sensitivity to water removal. The water consumption of Portland cement CEM 0 42.5H, Portland cement CEM I 42.5H SS, ground blast furnace slag and microcalcite was studied. It was found that all the studied mixtures of finely dispersed components did not show water separation or stratification during the experiment. It was shown that materials with a lower coefficient of water consumption and, therefore, having the lowest coefficient of strain, would be more susceptible to water detachment in SCC mixtures.FOR CITATION: Larsen O.A., Solodov A.A., Narut V.V., Butenko K.A., Veselov V.K.Study of the properties of finely dispersed materials for self-compacting concrete // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 359 – 368.
KEY WORDS:
aluminate cement, Portland cement, mixed binder, setting time, specific heat release, compressive strength.
ABSTRACT:
The purpose of this study was to establish the effect of the addition of aluminous cement in an amount from 0 to 100% by weight of a binder composition based on Portland cement on the properties of the cement paste and the compressive strength of the cement stone. For cement paste of various compositions, mobility, setting time, specific heat release, and compressive strength at 1, 7, and 28 days of hardening in wet conditions were determined. The results obtained indicate that when adding from 0 to 60% aluminous cement, the onset of setting occurs faster compared to cement paste made from Portland cement. Also, cement pastes containing aluminous cement from 0 to 70 % by weight were characterized by a rapid loss of cement paste mobility. Cement pastes with an amount of aluminous cement from 70 to 100% are characterized by prolonged setting: the beginning and end of setting occurred no earlier than 4 hours from the start of mixing the binder with water. With an increase in the content of aluminous cement in the binder composition from 0 to 40%, the heat release of the mixture increases. However, with a further increase in the amount of aluminous cement the heat release decreases sharply. With the introduction of from 0 to 70 % by weight aluminous cement, the compressive strength on the 1st, 7th, and 28th day of hardening decreases compared to the composition without additives.FOR CITATION: Solovyev V.G., Shvetsova V.A., Nguen Z.T.L. Study of the properties of a binder based on Portland cement // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 369 – 378.
KEY WORDS:
slag-silicate porous composite, cementless binders, arbolite, low-base hydrosilicates, hydro-aluminosilicates
ABSTRACT:
In connection with the growing demand for new high-performance building materials the topic of obtaining new composite materials on the basis of cementless binders are becoming more and more relevant. In this work some physical and chemical aspects of formation of structure of porous slag-silicate arbolite material are considered. Using methods: XRD, TGA and SEM analysis the nature of new formations formed during hardening of slag-silicate porous composite has been established. It was found that in the obtained composite new formations are represented mainly by low-base hydrosilicates and hydroaluminosilicates of different composition (mainly of group CSH(B)). The highest intensity of the appearance of these neoformations is observed in the sample hardened in the conditions of TWO at 90°С for 10 hours. The pore structure of the composite material was studied and it was found that the structure of the material is characterized by a uniformly distributed porosity with sizes, mainly ≥ 1 mm. This structure has a closed porosity with solid and even interstitial partitions, which may contribute to lower capillarity, water absorption, sorption wetting.FOR CITATION: Kheirbekov R. А., Samchenko S. V. Some physicochemical aspects of the formation of the structure of composite slag-silicate porous wood chip concrete material // Technique and technology of silicates. 2022.Vol. 29. No4. Pp 379 – 390.
Volume 29