One of the main priorities of present industrial activities is to reduce associated emissions, fulfilling the requirements to preserve the natural environment. Also, the road construction industry undertakes efforts to develop technologies permitting more sustainable production of asphalt mixtures, e.g. by utilizing reduced production and paving temperatures. The most effective technology in this respect is the half-warm mix asphalt technique (HWMA) with foamed bitumen, enabling the production temperature to be decreased to as low as 90°C - 110°C depending on the type of mixture, which is approximately 60°C lower than the production temperature of traditional hot mix asphalt (HMA). The present study evaluated a 50/70 asphalt binder foamed with water, intended to produce asphalt concrete. In order to ensure the most favorable characteristics of the foamed binder, i.e. maximum expansion ratio (ER) and half-life (HL), Fisher Tropsch synthetic wax was used in the amounts of 1.0, 1.5, 2.0 and 2.5% and a surfactant in the amount 0.2, 0.4 and 0.6% in relation to asphalt by weight before foaming. The utilization of the additives significantly improved the foaming characteristics of the investigated binder. Due to the fact that the asphalt binder is subject to aging, which affects the properties of the produced asphalt mixture and the durability of the asphalt pavement, the binders were subjected to short-term (RTFOT). The effects of the additives on the basic characteristics of the binders were evaluated after aging. The tests included penetration, softening point, and Frass breaking point. Statistical analysis of test results was performed using the ANOVA test. Certain compositions of the foamed asphalt binder were identified, which were characterized by more favorable properties than the reference asphalt binder. This permitted to conclude that it is possible to produce an asphalt mixture with high quality parameters using low-temperature technology with water-foamed asphalt.

Foamed asphalt binder; asphalt ageing process; synthetic wax; surface active additives