Bitumen Aging on the Surface of Igneousand Carbonate Rocks of Various Grain Size

The object of research is asphalt concrete mixtures. Experimental study of the aging process of bitumen films in the composition of bitumen-mineral mixtures consisting of dispersed mineral grains of various rocks (granites and limestones) of fractional composition fr. 5…20 mm, 0.315…5.0; 0.05…5.00 and 0.05…0.71 mm and BND 90/130 and BND 70/100. Method. The experiments were performed under the method covered by the Russian Federation Patent No. 2 654 954, proposed at the Volga State University of Technology (Department of Building Technologies and Highways). The assessment of the aging rate of bitumen-mineral mixtures was performed by: 1) establishing the values of the ultimate compressive strength at +50 °С for standard cylindrical samples (height and diameter 50×50 and 71.4×71.4 mm). The samples are formed from mixtures and stoved at +150 °С for 0…7 hours; 2) Calculating the values of the aging factor, the aging rate and analyzing the change in the values depending on the preheating time of the mixture at a high temperature. Results. Statistical processing of the data obtained during the experiments was carried out by the one-factor design method in the CurveExpert software environment. After that, mathematical models with a high correlation degree were obtained (S=0.432…0.13 578; r = 0.90 498…0.99 997). These mathematical models are mainly represented by Sinusoidal Fit; Harris and Exponential models and can be used to plan the operational behavior of materials in the composition of road structural layers.