IMPROVING THE STRUCTURAL AND MECHANICAL PROPERTIES OF WARM ASPHALT CONCRETEBY THE METHOD OF POLYMER-DISPERSE REINFORCEMENT

Statement of the problem. The problem of improving the structural and mechanical properties of warm asphalt concrete using the method of polymer-dispersed reinforcement is considered. The effect of the dosage of the RTEP-M modifier in the mineral part of the mixture on the structural and mechanical properties of warm mix asphalt (WMA) was studied. Results. By preparing a warm mix asphalt with mixing and molding samples at a temperature of 110--120 °C with the RTEP-M modifier at a ratio of 0.5; 1.0; 1.5 and 1.75 % of the mineral part and control mixtures, the effect of the modifier dosage on the structural and mechanical properties of WMA was studied. By testing the samples, the compressive strength of warm asphalt concrete at temperatures of 0.20 and 50 °C was determined, as well as the indicators of average density, water saturation and water resistance.Conclusions. The effectiveness of the application of the method of polymer-dispersed reinforcement to improve the structural and mechanical properties of warm concrete asphalt has been proven. It is shown that the addition of the RTEP-M modifier to the mineral part of the warm mix asphalt improves the strength characteristics of the asphalt concrete. It has been established that by applying the method of polymer-dispersed reinforcement, it is possible to optimize the properties of warm asphalt concrete for its use in cold or hot climatic conditions within the limits of indicators permissible according to the requirements of regulatory documents.

Influence of dispersed reinforcement on properties of road concrete obtained by vibropressing semi-dry mixtures

Problem and goal. The results of research of influence of dispersed reinforcement on properties of concrete semi-dry mixes, their ability to consolidation by vibropressing and strength characteristics of the received concrete are resulted. Metodology and result. In the first stage of research, steel anchor fiber was used as a dispersed fiber, the second stage was devoted to vibropressing mixtures with basalt fiber. In order to establish the influence of the parameters of the composition of vibropressed reinforced concrete and to obtain quantitative dependences of the main properties for their use in the design of the composition, a planned experiment was conducted. The regression equations for water consumption, average density of compacted concrete mixture, compressive strength and tensile strength during splitting at the age of 28 days were obtained. The analysis of the obtained equations showed that the dispersed reinforcement of concretes from semidry mixture with steel fiber is associated with a complicated distribution of fiber, which necessitates an increase in water content, the introduction ofincreased amounts of plasticizers. Vibropressed reinforced concrete has increased values of tensile strength in splitting and compression, which allows it to be recommended for the manufacture of road elements. It was found that basalt fiber is much better distributed during mixing and, unlike steel, less interferes with compaction. Disperse reinforcement of vibropressed concrete with basalt fiber allows to obtain values of tensile strength in bending within 10…13 MPa. This strength is 40…50% lower than when using steel fiber, but when vibropressing basalt fibers are more technological: improve the molding properties, provide greater homogeneity of concrete, allow to produce products with less wall thickness and any complex configuration. Originality. The obtained mathematical models of influence of factors of composition of vibropressed fibroconcrete on its mechanical and technological properties gave the chance to offer a way of designing of structure of such concrete with maintenance of a complex of necessary parameters and the minimum cost of components.

IMPROVING THE STRUCTURAL AND MECHANICAL PROPERTIES OF WARM ASPHALT CONCRETE BY THE METHOD OFPOLYMER-DISPERSE REINFORCEMENT

Постановка задачи. Рассматривается задача повышения структурно-механических свойств теплого асфальтобетона путем применения метода полимерно-дисперсного армирования. Исследуется влияние дозировки модификатора РТЭП-М в минеральную часть смеси на структурно-механические свойства теплой асфальтобетонной смеси (ТАС). Результаты. Приготовлены теплые асфальтобетонные смеси с температурой смешивания и формовки образцов 110-120 °C с модификатором РТЭП-М при соотношении 0,5; 1,0; 1,5 и 1,75 % в минеральной части и контрольные смеси. С их помощью изучено влияние дозировки модификатора на структурно-механические свойства ТАС. Испытаниями образцов была определена прочность при сжатии теплого асфальтобетона при температурах 0, 20 и 50 °C, а также показатели средней плотности, водонасыщения и водостойкости. Выводы. Доказана эффективность применения метода полимерно-дисперсного армирования для повышения структурно-механических свойств теплого асфальтобетона. Показано, что добавление модификатора РТЭП-М в минеральную часть теплой асфальтобетонной смеси улучшает прочностные характеристики асфальтобетона. Установлено, что путем применения метода полимерно-дисперсного армирования можно оптимизировать показатели свойств теплого асфальтобетона для его применения в холодных или жарких климатических условиях в пределах показателей, допустимых по требованиям нормативных документов. Statement of the problem. The problem of improving the structural and mechanical properties of warm asphalt concrete using the method of polymer-dispersed reinforcement is considered. The effect of the dosage of the RTEP-M modifier in the mineral part of the mixture on the structural and mechanical properties of warm mix asphalt (WMA) was studied. Results. By preparing warm mix asphalt with a mixing and molding samples at a temperature of 110-120 °C with the RTEP-M modifier at a ratio of 0.5; 1.0; 1.5 and 1.75% of the mineral part and control mixtures, the effect of the modifier dosage on the structural and mechanical properties of WMA was studied. By testing the samples, the compressive strength of warm asphalt concrete at temperatures of 0, 20 and 50 °C was determined, as well as the indicators of average density, water saturation and water resistance. Conclusions. The effectiveness of the application of the method of polymer-dispersed reinforcement to improve the structural and mechanical properties of warm concrete asphalt has been proven. It is shown that the addition of the RTEP-M modifier to the mineral part of the warm mix asphalt improves the strength characteristics of the asphalt concrete. It has been established that by applying the method of polymer-dispersed reinforcement, it is possible to optimize the properties of warm asphalt concrete for its use in cold or hot climatic conditions within the limits of indicators permissible according to the requirements of regulatory documents.

TECHNOLOGICAL FEATURES OF THE DISPERSE REINFORCEMENT OF FINE-GRAINED CONCRETE WITH FIBERS OF DIFFERENT MATERIALS

The article presents the technological features of the disperse reinforcement of finegrained concrete fiber reinforcement, made of different materials.

Fine-Grained Polymer-Cement Basalt Fibrous Concrete for 3D Printing

The construction concrete printing requires new approaches at reinforcement performing. Only successful integration of the existing reinforcement systems will provide for the opportunity to design concrete structures and make objects with the help of additive technologies. The paper dwells upon the issues of possibilities and the efficiency of disperse reinforcement with basalt fibers. It presents a composition of a composite material for 3D printing of a type of fine-grained fibrous concretes with the required technological properties: a necessary plasticity and a high plastic strength for printing large-dimensioned items and structures without timbering by means of extrusion with a high material adhesion between the layers and controlled setting periods. The author studied a possibility to reclaim basalt fiber production wastes as a high-disperse fibrous filler for the reinforcement of polymer-modified concretes. The article provides the dependence of plastic strength on the fiber content in concrete. The authors consider the influence of components and the mechanism of modifying disperse particles of basalt fibrous concrete at obtaining the material for 3D printing. The obtained polymer-modified basal fibrous concrete has a good impact resistance, low water absorption and high crack resistance.

Effect of Disperse Reinforcement on the Structural Quality Factor of Vibrated and Centrifuged Concretes on the Сombined Aggregate

The article considers and evaluates the impact of dispersed reinforcement of vibrated and centrifuged concretes manufactured with various types of fibers on their strength-density ratio. The authors considered the application of such a recipe manufacturing method as combining aggregates by the example of heavyweight aggregate - crushed stone and light aggregate - expanded clay aggregate for these concretes. Registered strength-density ratio of centrifuged fibrous concretes with a combined aggregate is higher than vibrated concretes with the same composition of the studied fibers. The highest growth of the strength-density ratio for the centrifuged fibrous concretes as compared with the vibrated ones was identified in case of dispersed reinforcement with steel fiber.

Modeling of Aerated Cement Concrete Structure and Increasing its Crack Resistance

In this article is described a problem of increasing crack resistance of aerated cement concrete. Authors, having a model of concrete’s structure, made a disclosure of ratios for calculation of parameters the aerated concrete with disperse reinforcement. These ratios show data about change of structure parameters of aerated concretes with disperse reinforcement such as different density by variation of factors water-cement ratio, percent of reinforcement, ratio between dosing of cement and sand. Concrete’s cracking resistance was evaluated by compressive strength and parameter KIc. As result of experimental data processing authors got regression’s equations, which adequately describe changes of fracture toughness and compressive strength of aerated cement concrete (foam concrete) with density 1200 kg/m3 and 1400 kg/m3 in limits of factor area. There was shown a possibility of two-time increasing of fracture toughness and strength of aerated cement concrete with disperse reinforcement its structure by rough basalt fiber.

Calculation of the normal section strength of rubcon beams using deformation diagrams

Rubber concrete (rubcon) - polymer concrete, which has high strength properties, as well as the constructions made of it. Fibrorubcon – rubber concrete with the addition of disperse reinforcement. On the basis of test results for pure bending, empirical dependencies and prerequisites for adapting existing methods for calculating the strength of normal sections of rubcon and fibrorubcon beams were obtained. These studies allow developing methods for calculating the normal cross sections of bending elements made of rubber concrete using deformation diagrams and taking into account the work of stretched polymer concrete.