INCREASE OF ASPHALT RECYCLING BY USING PYROLYSIS PRODUCTS OF WASTE TIRES

Bitumen, which is the most important component of asphalt and has the biggest impact on its behaviour, is ageing during the use of asphalt layers. Ageing of bitumen is most frequent cause for degradation of asphalt layers. Finally this leads to the removal of asphalt layers. But asphalt granulate obtained from the removed asphalt layer can be added to freshly produced asphalt mixtures. Using special additives, i.e. rejuvenators, bitumen can regain its basic properties, and in this way we can increase the proportion of asphalt granulate added to the asphalt mixture. We developed alternative rejuvenator with the process of pyrolysis of waste tires [1]. First, we tested the efficiency of the various pyrolytic products that were produced by varying the time and temperature of the pyrolysis. Various concentrations (3 %, 5 %, 10 % and 20 %) of the most suitable pyrolytic product were mixed into bitumen. We examined its effect on the viscoelastic properties of fresh and laboratory aged bitumen [2]. With standard mechanical tests, rheological investigations and rheological modelling, we have proven that with the addition of the alternative rejuvenator to aged bitumen some basic properties of bitumen are regained. We determined the most appropriate bitumen content that should be added to a mixture of fresh asphalt and reclaimed asphalt. Finally standard tests of asphalt mixtures showed that the addition of rejuvenator improves the properties of asphalt mixtures containing the reclaimed asphalt, and the rate of recycling can be increased. Reuse of reclaimed asphalt means reducing waste material and so preserving the environment.