Analysis of calculation methods for determining the brittleness temperature of bituminous binders

Abstract

Problem. One of the common causes of premature destruction of road surfaces is the unsatisfactory low-temperature properties of bituminous binders and asphalt concrete. Currently existing methods of determining the low-temperature properties of road bituminous binders are based on the use of complex and expensive laboratory equipment and involve the highly professional specialists in the testing and interpretation of the obtained data. Meanwhile, calculation methods for determining the brittleness temperature of bitumen and bituminous binders can be useful quite often for the preliminary assessment of low-temperature characteristics of binders. Goal. The purpose of the completed work is to establish the principle used in calculation methods for determining the brittleness temperature of bituminous binders and to estimate the possibility and feasibility of using various methods for evaluating the low-temperature characteristics of binders used in the road industry of Ukraine. Methodology. To achieve the goal, an analysis of literary sources devoted to calculation methods for evaluating low-temperature characteristics of bituminous binders was carried out, and a comparison of brittleness temperature values determined by experimental and calculation methods was performed. Results. During the analysis of literary sources, it was established that the vast majority of currently known calculation methods for determining the brittleness temperature of bitumen are based on the establishment of a relationship between standard indicators of their quality – penetration at 25 ºС, brittleness temperature (as the temperature at which penetration is equal to 1.25 × 0 .1 mm) and the temperature of softening (as the temperature at which the penetration is equal to 800 × 0.1 mm). Calculation methods for determining the brittleness temperature are based on the principle proposed by W. Heuckel, namely the temperature-penetration dependence, which is linear in a wide temperature range. Practical value. The accuracy of determining the brittleness temperature according to domestic calculation methods was checked and the most acceptable one was established, which allows to calculate the brittleness temperatures that are the least different from those experimentally determined by the Fraas method.