The research is devoted to developing the production of crumb rubber-modified bitumen with improved stability. It has been established that the most suitable semi-empirical coefficient for determining the compatible plasticizer to crumb rubber is based on the ratio of paraffin-naphthenic compounds to resinous-asphaltene compounds. With the help of differential scanning calorimetry, temperature regimes of crumb rubber destruction and preparation of rubber-containing components (210 °C) were studied and determined. It was established that determining the dynamic viscosity of hydrocarbon concentrates with crumb rubber on a rotary viscometer is not applicable due to elastic components, making it difficult to measure and obtain reliable data. The most suitable method is the shear viscosity method. Using fluorescent microscopy, it was established that the formation of a branched structure of crumb rubber is achieved in the waste industrial oil, indicating devulcanization processes. It was found that hydrocarbon plasticizer with high naphthenic oil content is the most compatible with crumb rubber. Synthetic wax was found to be of greater interest as a devulcanizing/stabilizing agent, and its application in an amount of 3% allows the formation of a stable CRMB structure and stabilizes the devulcanization process.

The issue of forming a reliable and sustainable structure of crumb-rubber-modified binder is an important scientific and technical task. The quality of this task will increase the technical and economic efficiencies of road construction materials. This work is dedicated to developing a scientifically justified method of directed thermomechanical devulcanization, which ensures the solubility of the crumb rubber in the complex structure of a polydisperse composite material, preventing the formation of aggregates consisting of unsaturated crumb rubber particles, whose elastic aftereffect causes intensive cracking, especially during low-temperature road operations. The novelty in the first part of this article is due to the fact that, for the first time, the quantitative ratio of the polymer component in the crumb rubber was experimentally determined. The ratio of the polymer component to the total content of the other rubber components in the crumb rubber (CR) was determined to be, on average, 93.3 ± 1.8%. The stabilities of the compositions of crumb rubber from different batches were experimentally studied. The nature of the polymer component in the crumb rubber was determined. A hypothesis was formulated to obtain a thermodynamically stable and sustainable binder modified with crumb rubber. To evaluate the compatibility of hydrocarbon plasticizers with the studied CR samples, the following semi-empirical and thermodynamic compatibility parameters were calculated: Hildebrand solubility parameters based on evaporation energy and surface tension, Barstein’s compatibility parameter |X|, Traxler coefficient, and the mass ratio of paraffin naphthene:asphaltenes. It was shown that for the substances under study, it is advisable to justify the choice of plasticizer based on chemical compatibility criteria. It was established that a supramolecular plasticization mechanism occurs in the “hydrocarbon plasticizer–crumb rubber” systems under consideration. In the development of the crumb-rubber-modified binder, it was found that the use of activated crumb rubber (ACR) from large tires does not ensure the achievement of a stable and resilient structure of the crumb-rubber-modified bitumen.

The issue of forming a reliable and stable structure of a crumb-rubber-modified binder is an important scientific and technical task. The authors supplemented existing concepts of the mechanism of effective interaction with rubber crumb by introducing a preliminary first stage: controlled partial physical destruction of rubber crumb—producing rubber reclaim. Proposed physical methods of rubber crumb destruction include high shear force (roll mills), high temperature, and a plasticizing medium. The controllability and degree of devulcanization of rubber were determined by acetone-chloroform extraction in different time intervals. The degree of devulcanization of rubber in the rubber reclaim was found to be 22 ± 0.24%, with stability over 14 days. It was found that the size of the particles of the rubber reclaim in the bitumen is less than 2 µm. The properties of the structure of the binder modified with rubber reclaim, characterizing the stability and sustainability, have been studied and established. The developed modified binders are stable in storage. Rheological parameters of the structure characterizing intermolecular interaction, such as shear stability for original and RTFOT-aged, modified bitumen, meet requirements of the state standard at test temperature 64 °C. The elastic structural component of the crumb-rubber-modified binder, as indicated by the relative irreversible deformation parameter J_3,2, does not exceed 2.6 kPa (<4.5 kPa) at 64 °C. Additionally, it was determined that the rheological structural parameter for fatigue resistance, which characterizes the durability of road pavement under intensive operational conditions, does not exceed 4699 kPa (<5000 kPa) at 16 °C. The use of 10% rubber reclaim combined with waste frying oil provided the opportunity to obtain a modified binder with a stable and sustainable structure without the introduction of additional stabilizers and agents. Test results showed that the overall performance characteristics of the modified binder meet the 64(S)-40 grade standards.

Повышение эксплуатационной надежности и стабильности резинобитумных вяжущих остается актуальной задачей в условиях перехода к ресурсосберегающим технологиям дорожного строительства как элемента экономики замкнутого цикла. В настоящей работе представлены результаты разработки стабильного резинобитумного вяжущего, устойчивого к термоокислительному старению. В качестве модификатора использована модифицированная резина, полученная путем вальцевания в среде мазута при температуре 150 °С, что обеспечивает получение однородной термопластичной пленки. Дополнительное введение смеси отработанных растительных масел в вяжущее способствовало совместимости фаз и формированию устойчивой дисперсной системы. Для оценки однородности и стабильности вяжущего применены регламентированные показатели: изменение температуры размягчения, пенетрации после длительного термоокислительного старения, однородность и расслоение. Получены адекватные экспериментально-статистические (регрессионные) модели, устанавливающие зависимости показателей стабильности от рецептурных факторов, с применением которых по критериям расслоения и термической нестабильности установлены оптимальные диапазоны варьирования компонентов резинобитумного вяжущего. Полученные результаты демонстрируют перспективность разработанного подхода для создания стабильных и ресурсосберегающих резинобитумных композиций.