Introduction. In this review, epoxy components, in particular epoxy resin and its hardener (thermoactive polymer additives), are defined as the main component of epoxy-bitumen composite (hereinafter — EBC), which is part of the asphalt concrete mixture. The article is aimed at highlighting the results of research conducted to determine the physical and mechanical properties of thin-layer asphalt concrete pavement with the use of EBC for its use on highway bridges.
According to the results of laboratory tests, epoxy asphalt concrete (hereinafter — EAB) can be considered one of the best choices for the next generation of durable materials for the installation of thin-layer coatings on highway bridges due to their excellent mechanical properties and thermal stability, as well as economic viability, taking into account the absence of the need for waterproofing of the bridge deck, excessive maintenance and repair costs and a long service life.
Problem statement. One of the main mechanisms of destruction of asphalt concrete coatings on highway bridges, especially with orthotropic slabs, is its constant dynamics from external influences, which causes significant deformations that mercilessly affect the durability of the entire bridge structure.
Taking into account the thermoreactive nature of epoxy components, the idea of using them as a bitumen modifier arose in order to minimize deformations of the asphalt concrete coating on bridges, reduce the load from the weight of the bridge deck on span structures, and also increase the resistance of the coating to the influence of aggressive environments.
In order to obtain high-quality research results for the further possibility of ensuring the installation of coatings on bridges with the best operational characteristics and the most efficient use of labor and resources, studies of the physical and mechanical characteristics of EAB were carried out according to the Superpave methodology.
Objective. The purpose of this article is to present the physical and mechanical characteristics of EAB in comparison with other ordinary asphalt concrete on polymer bitumen for the qualitative assessment of the use of EBC during the manufacture of epoxy-asphalt concrete mixtures (hereinafter — EABS) and to determine the real possibility and level of efficiency of using such mixtures for the installation of bridge pavements on automobile roads roads, taking into account the main goal — to increase its durability at various load frequencies due to the improvement of strength, crack resistance and, of course, rut resistance.
To achieve the specified goal, a set of experimental studies was conducted, with a comparison of the characteristics of EAB and a number of Superpave protocols of the tested asphalt concretes on polymer bitumen, such as:
limit of compressive strength at temperatures of 50 °С, 20 °С and 0 °С;
density and water saturation;
limit of tensile strength at splitting;
stability, conditional plasticity and index of conditional stiffness according to the Marshall method;
resistance to rutting.
Particular attention was paid to determining the resistance of EAB to the formation of rutting, because during the implementation of certain stages of research it was found that when positive test results were obtained for other indicators, in particular for strength indicators, it is far from a fact that the material is able to pass the rutting resistance test.
After the completion of the corresponding comprehensive field test of the bridge covering with EAB, a quantitative assessment of the effectiveness of its use in comparison with similar types of coverings designed to increase the service life (from 30 to 40 years) is planned.
Materials and methods. A thin-layer asphalt concrete coating on bitumen modified with thermoreactive polymer additives for its use on an orthotropic or reinforced concrete slab of the carriageway of a road bridge.
Results. The physical and mechanical properties of EBC were evaluated, the level of efficiency and the possibility of its use in asphalt concrete thin-layer coatings on highway bridges were determined to improve quality and increase durability. A set of laboratory studies was conducted to compare the properties of EAB and traditional asphalt concrete on polymer bitumen.
Conclusions. After a detailed study of EAB components and a review of the system and hardening mechanism, its physical and mechanical properties were studied. Tests have shown that EAB is a stiffer material compared to conventional asphalt on polymer bitumen and has demonstrated significantly higher compressive strength, much better rutting resistance, as well as excellent properties of splitting tensile strength, stability, conditional plasticity, conditional stiffness and waterproof. The low temperature test performance of EBC was significantly higher than polymer bitumen, and the tensile strength results showed that it is more resistant to cracking at low temperature. Therefore, it can be concluded that EAB has a certain perspective for use as a coating on an orthotropic or reinforced concrete slab of the carriageway of a road bridge. However, its use requires special attention when determining the duration and temperature of EBC hardening, as well as when selecting the optimal composition and preparation technology, because non-compliance with the specified can significantly affect its physical and mechanical properties.
