The Effect of Synthetic Wax and Technological Aging on the Rheological Properties of Polymer Modified Asphalt Binders

Abstract

The intensive development of transport and especially the increase in the number of trucks with a general traffic structure makes it necessary to use polymer-modified asphalts binder in the production of asphalt mixtures. They are characterized by high physical and mechanical parameters and can meet the requirements that are imposed on them. However, as a result of technological ageing during the production of the asphalt mixture and operational ageing, the binder parameters are reduced. In order to slow down this process, various types of additives are used, which act as ageing inhibitors. These types of materials include low-viscose additives, which include Fisher-Tropsch synthetic wax. At the same time, such additives affect the reduction of technological temperatures of the production and incorporation of the asphalt mixture, which is very beneficial in terms of environmental protection. There are reductions in greenhouse gas emissions and the energy consumption of the production of the asphalt mixture is reduced. The synthetic wax F-T was used in the tests, which was dosed to the PMB 45/80-65 polymer asphalt binder in the amount of 0.0%, 1.5%, 2.5% and 3.5%. Then the binder was subjected to technological ageing (short-term ageing). In the first stage of the tests, the penetration at 25°C, softening temperature and critical temperatures during the low-temperature parameter testing were determined. In the second stage, the following rheological characteristics were tested in the range of linear and non-linear viscoelasticity: zero shear η0, dynamic modulus |G*|, phase shift angle δ and MSCR parameters. Based on the analysis of the test results, it was found that the synthetic wax reduced the susceptibility of the polymer asphalt at medium and high operating temperatures and affected the reduction of its ageing rate while increasing the elastic part of the dynamic modulus. Synthetic wax increased the zero shear viscosity level of the binder, which will have a beneficial effect on reducing the deformation rate of the asphalt mixture and ensure the required operational durability of the surface.