Optimization of composition of asphalt concrete with synthetic wax modified foamed bitumen in scope of resistance to climatic conditions

Abstract

The research concerned moisture and frost resistance of asphalt mixes for binder course produced with foamed bitumen with variable amount of synthetic wax was conducted. The wax was added to the bitumen in amounts of 1.0% to 2.5% in relation to the mass of bitumen and four concentrations of the binder were investigated: 4.3%, 4.5%, 4.8% and 5.1%. In total, 16 different bituminous mixtures were prepared and compacted at 95°C, therefore falling into warm-mix asphalt category. The obtained results were used as a base for a multivariable optimization, i.e. assessing the foamed bitumen and synthetic wax contents that would result in a bituminous mixture resistant to adverse climatic conditions. The optimized variables included: indirect tensile strength retained ITSR, indirect tensile strength at -2ºC in accordance to PANK 4302 and modified AASHTO T283 method.