Effects of commercial waxes on asphalt concrete mixtures performance at low and medium temperatures

Effects of adding two commercial waxes to three 160 / 220 penetration grade bitumens in asphalt concrete mixtures were studied using tensile stress restrained specimen test (TSRST), dynamic creep test and complex modulus test. Significant physical hardening of binders, observed in binder testing, could not be observed using TSRST. The reason could be that low temperature physical hardening does not have a large effect on fracture properties of the asphalt mix or that TSRST is a non-suitable test for showing these effects. In dynamic creep testing, the smallest strains were recorded for the asphalt mixture containing non-waxy bitumen and FT-paraffin, indicating better resistance to rutting. In complex modulus testing, adding of 6% commercial wax clearly increased the modulus and decreased the phase angle, an effect more pronounced for the mixture containing FT-paraffin compared to the one containing polyethylene wax.