Effects of Cold Climate on Mechanical Performance and Permeability of Porous Asphalts Treated with Waxes

The paper aims to evaluate the application of Warm Mix Asphalt technologies to Porous Asphalts in cold climate regions, reporting an experimental work carried out at Warsaw University of Technology, (Poland) and Polytechnic University of Bari (Italy). Indirect Tensile Strength (ITS) as well as water permeability tests have been performed on samples of a selected porous asphalt, with and without the Sasobit wax. Mixing and compacting temperatures were varied during tests. Permeability and ITS tests were performed both in standard condition and after a severe water/temperature conditioning process in order to evaluate its influence on the specimens. ITS results indicate that the addition of the wax increases the performances of the porous asphalt. After the water/temperature conditioning this increment disappears, resulting in the WMA samples (with wax) more sensible to the conditioning process than HMA samples (no wax addition). The same sensibility was found for horizontal permeability: in presence of wax the permeability results greater, but this increment disappears after conditioning process. In order to better analyze the influence of conditioning process on porous asphalt with waxes, permeability results were pre-processed testing the normality and homoscedasticity assumptions and multivariate regression models were developed for ITS results. The experimental and statistical results confirmed that wax technology provides better performances in terms of ITS and permeability before the conditioning. After the conditioning process, the performances became similar to the traditional technologies. In any case, wax allows to lower the compaction temperatures by about 20°C with no significant decrement in mixture performance