Thermosetting Binder for Fibrous Insulating Materials

Постановка задачи. Модернизация систем изоляции инженерных сооружений, в том числе и трубопроводов и промышленных объектов, направлена как на решение общих задач энергоэффективности, так и частных задач теплосбережения и экологической безопасности. В связи с этим разработка и применение связующего, отверждаемого при значительно меньших температурах и не содержащего фенолы, является актуальной задачей. Результаты. Эксперимент, проведенный для оценки влияния на адгезию к различным поверхностям комплексного связующего, отверждаемого в температурном интервале от 80 до 140 С, позволил определить оптимальные расходы латентного компонента и модификатора, которые составили соответственно 3,6-4,0 % и (2,6 ± 0,1) % по массе связующего при оптимальной температуре тепловой обработки 100 С. Расчетом установлено, что при переходе от тепловой обработки при 250 С к тепловой обработке при 100 С прямые затраты тепла снижаются на 60 %, а энергетические затраты на изготовление минераловатных цилиндров на 20-30 %. Выводы. Теоретически обоснована и экспериментально подтверждена возможность применения эпоксидного клея на латентных отвердителях в качестве связующего для высокопористых систем с распределением и отверждением этого связующего на тонких минеральных волокнах. Определены характеристические параметры процесса отверждения, длительность которого уменьшается с повышением температуры и содержания латентного отвердителя. Statement of the problem. The modernization of insulation systems of engineering structures, including pipelines and industrial facilities, is aimed both at solving general problems of energy efficiency, as well as the particular tasks of heat saving and environmental safety. Therefore the development and use of a binder that cures at much lower temperatures and does not contain phenols is an urgent task. Results. An experiment conducted to assess the effect on adhesion to various surfaces of a complex binder cured in the temperature range from 80 to 140 °C allowed us to determine the optimal flow rate of the latent component and modifier, which were 3.6-4.0 % and (2.6 ± 0.1) % respectively by the weight of a binder at an optimal heat treatment temperature of 100 °C. The calculation suggests that when switching from heat treatment at 250 °C to heat treatment at 100 °C, direct heat costs are reduced by 60 %, and energy costs for the manufacture of mineral wool cylinders by 20-30 %. Conclusion. The possibility of using epoxy glue on latent hardeners as a binder for highly porous systems with the distribution and curing of this binder on thin mineral fibers has been justified theoretically and confirmed experimentally. The characteristic parameters of the curing process have been identified whose duration decreases as temperature and the content of latent hardener increase.

THERMOSETTING BINDER FOR FIBROUS INSULATING MATERIALS

Statement of the problem. The modernization of insulation systems if engineering structures, including pipelines and industrial facilities, is aimed both at solving the general problems of energy efficiency, as well as the particular tasks of heat saving and environmental safety. In this regard, the development and use of a binder that cures at much lower temperatures and does not contain phenols is an urgent task. Results. An experiment conducted to assess the effect on adhesion to various surfaces of a complex binder, cured in the temperature range from 80 to 140 °C, allowed us to determine the optimal flow rate of the latent component and modifier, which were respectively 3.6--4.0 % and 2.6±0.1 % by weight of a binder at an optimal heat treatment temperature of 100 °C. The calculation established that when switching from heat treatment at 250 °C to heat treatment at 100 °C, direct heat costs are reduced by 60 %, and energy costs for the manufacture of mineral wool cylinders by 20--30 %. Conclusion . The possibility of using epoxy glue on latent hardeners as a binder for highly porous systems with the distribution and curing of this binder on thin mineral fibers was justified theoretically and confirmed experimentally. The characteristic parameters of the curing process were determined, the duration of which decreases with increasing temperature and the content of latent hardener.

USE OF ACRYLIC COPOLYMER ADDITIVE SOIL STABILIZATION PLUS FOR PREPARATION OF MIXTURES MADE BY COLD RESYCLING TECHNOLOGY AND CRUSHED STONE-SAND MIXTURES IN PAVEMENT FOUNDATION LAYERS

ntroduction. Rehabilitation of public roads network requires a comprehensive recovery with strengthening of the bearing capacity of the pavement foundation. Rehabilitation of the foundation bearing capacity performed by arranging layers of road material made by cold recycling technology (hereinafter — CRRM) in accordance with [4] or by arranging a layer of crushed stone — sand mixture reinforced with cement or complex binder (hereinafter — CSSM 20) according to [13]. Purpose. The purpose of the work is to study the feasibility of using acrylic additives for the preparation of mixtures made by cold recycling technology and crushed stone-sand mixtures treated with cement in the layers of pavement foundation. Materials and methods. Experimental comparative tests of CRRM and CSSM 20 with different content of complex binder were performed. Results. Feasibility of acrylic additives use has been established (hereinafter — the additive) for the preparation of CRRM and CSSM 20 in the pavement foundation layers. Recommendations on technological parameters of preparation, transportation, laying and compaction of mentioned mixtures are given. Conclusions. Performed researches have shown that according to physical and mechanical indicators CRRM and CSSM20 meet the requirements of the current normative documents of Ukraine. The advantages of use are noted.

PROSPECTS FOR THE APPLICATION OF COPPER MELTING SLAG IN ROAD CONSTRUCTION

The article discusses the option of strengthening the soils of the roadbed of highways with complex binders based on granular slag of copper smelting production and air lime. The characteristics of the investigated slag, photomicrographs of its surface, as well as the chemical and phase compositions are presented. A detailed description of the X-ray diffractogram of the studied slag with the processing of the obtained reflections using the ICDD PDF-2 database is presented. Calculations of hydrolytic equilibria were carried out using the main phases found from the data of X-ray phase analysis. It was found by the calculation method that at pH = 11-12 in the lime-slag mixture decomposition of iron silicates and aluminosilicates occurs with the formation of gels of iron and aluminum hydroxides, as well as amorphous silica. On the basis of the obtained complex binder, standard samples of strengthened soil based on loam were made and tested to determine the physical and mechanical properties. The results of the experiments carried out create an opportunity for obtaining hardened soils based on a complex mineral binder with a compressive strength of up to 2.2 MPa.

Structure Formation and Properties of Concrete Based on Organic Hydraulic Binders

The article addresses the issues of structure formation of road composite materials containing hydraulic (рortland cement) and organic (bitumen) binders. It has been determined that organic and hydraulic binders, being thermodynamically incompatible, are capable of interaction and complement each other. Structure formation processes are associated with interphase transition layers interaction mechanism and the direct formation of phase contacts with cement crystallohydrates. The interphase boundary is diffuse and is established through interphase transition layers. The emergence of interfacial layers is thermodynamically advantageous, since it contributes to a decrease in Gibbs free energy and does not contradict modern concepts of solid state physics. It was established that with cement content of about 30 % of complex bitumen-cement binder volume, there will appear (nucleate) phase contacts that will prevail in the binder structure when the cement content is more than 60 %. In the case phase contacts prevail, concrete will demonstrate significant strength at high temperatures, but low temperature and fatigue crack resistance, which will lead to their durability loss. The cement content of 30–40 % of the total complex binder can be considered optimal.

EFFICIENCY OF REINFORCEMENT OF TECHNOLOGICAL SOIL BY MINERAL MODIFIERS

The paper discusses the main aspects of soil reinforcement in road construction by adding a binder component to them. The use of this technology allows to solve the problem of high-quality raw materials shortage while improving the physicomechanical characteristics or keeping them at the same level, as well as to increase labor productivity and reduce production costs. The technogenic raw materials for the production of soil concrete were studied, the main physicomechanical characteristics and requirements that must be taken into account when selecting the composition of the soil concrete mixture were analyzed. The paper compares the physicomechanical characteristics of the road composite, reveals the advantages and disadvantages of introducing binder components of various types: cement, cement with modifier and a complex binder. It has been established that the introduction of a complex binder or cement with modifier contributes to the improvement of the physicomechanical characteristics while reducing the consumption of cement in the composition of the soil-concrete mixture compared to traditional soil-concrete with cement.