The influence of mineral powders on the resistance of bitumen binder to thermal deformations

Introduction. The complex influence of dynamic loads, climatic factors, and aggressive environments is the driver of premature deformation of asphalt concrete pavements. The main types of failure are: plastic rutting deformations occurring at high temperatures above zero; fatigue cracks in the pavement caused by repeated loads; low-temperature transverse cracks occurring in the area with temperatures below zero while pavement cooling. According to modern concepts, the contribution of the binder to the formation of the described defects reaches 90–100 %. However, bitumen loses its original properties, interacting with mineral powder and forming an asphalt binder, which acts as a binder in asphalt concrete. Therefore, it is advisable to predict the behavior of asphalt concrete in a wide range of temperatures, and especially in low-temperature part, relying not on the bitumen binder, but on the asphalt binder. Materials and methods. Experimental laboratory studies of materials were carried out in accordance with GOST 33133–2014, GOST R 58400.1–2019, GOST 32761–2014, GOST 58401.1–2019, GOST R 58400.8–2019, GOST R 58400.11–2019. The objects of study were bitumen filled with mineral powders from limestone and dust from electric filters of an asphalt concrete plant. Results. Significant changes in the properties of the original bitumen were revealed under the influence of varying degrees of filling with mineral powder from limestone and dust from electric filters. It was shown that filling the binder with mineral powder (dust) in the maximum permissible concentration limit changes the PG (X) brand parameter by three positions from 64 °C to 82 °C. More fundamental data were obtained for the low-temperature stability of samples with a collapse of the parameter (± Y) from -34 °C to -22 °C. By identifying the parameters responsible for low-temperature cracking of the system at the binder level of asphalt, it is possible to scale the knowledge to asphalt concretes.