Assessment of Thermal Aging of Bitumen-Mineral Materials in Various Ways

Abstract

Bitumen-mineral materials prepared from mixtures of mineral materials with petroleum bitumen undergo aging during preparation, installation in engineering structures and during operation. For the accelerated study of the aging processes of bitumen in the composition of mineral materials, methods for warming up the samples of mixtures at high temperatures, methods of preheating and further freezing–thawing of samples, and others were obtained. The aging of bitumen is also judged by the change after heating in the furnace at + 163 °C for 5 h (RTFOT method). The main disadvantage of the latter method is that it does not take into account the influence of the interaction of the bitumen film with the surface of mineral components on the aging processes of bitumen-mineral materials. Since the thickness, structure and, accordingly, the stability of bitumen films on the surface of mineral components depend on their type and size, the aging processes of bitumen-mineral materials as a whole occur in different ways and this must be taken into account. The purpose of the work is to evaluate the thermal aging of bitumen-mineral materials by various methods. Method. The authors have proposed a special technique that allows us to study the aging processes of bitumen-mineral materials of both single-component and multicomponent structures at any high temperatures. The degree of aging of bitumen-mineral materials was carried out by establishing the values of the compressive strength of the materials under study, which were previously maintained respectively at +150 °C for 0, 1, 3, 5 and 7 h. Results. The analysis of the aging processes of bitumen-mineral materials was carried out by comparing the values of the aging coefficient at each stage of heating. The establishment of the values of the aging coefficient according to the new method makes it possible to accelerate the evaluation of comparative resistance against aging. Mathematical models have been developed that reflect the aging processes of bitumen-mineral materials depending on the preheating time at high temperatures. Models can be used to evaluate aging processes.