Increasing the rate of recycled asphalt: an experimental study

• Main Authors: Marjan TUŠAR, Lidija AVSENIK
• Format: Article
• Language: English
• Published: Silesian University of Technology 2014-09-01
• Series: Transport Problems
• Subjects: reclaimed asphalt; recycling; rejuvenator; asphalt plant
• Online Access: http://transportproblems.polsl.pl/pl/Archiwum/2014/zeszyt3/2014t9z3_04.pdf

Asphalt is material that can be recycled. In particular reclaimed asphalt (RA) contains aged binder, which limits the reuse of RA. In this study the rate of recycled asphalt was increased by adding a rejuvenator containing paraffin. The authors investigated the effect of the rejuvenator in laboratory and in plant prepared samples of asphalt mixture. In laboratory samples with different percentage of RA (0%, 10%, 30%, 50%) and rejuvenator were prepared. In asphalt plant only asphalt mixture with highest amount of RA and rejuvenator and control mixture without RA were prepared. On samples were conducted different tests, e.g. determining softening point, Fraass breaking point, penetration, indirect tensile strength. Results on extracted bitumen showed increase in softening point and decrease in Fraass breaking point with increasing percentage of RA and rejuvenator, meaning that service temperature of binders increased. Asphalt samples prepared in asphalt plant were laid on test field. Asphalt with RA and rejuvenator was built in at lower temperature (round 100 °C). Mixtures with RA and rejuvenator have better low temperature properties confirmed with Thermal Stress Restrained Specimen Test (TSRST) method, but are less resistant to compaction and less sensitive to water than control mixture. For comparison of long term behaviour wheel tracking test was performed on mixtures built in test field. A week after paving, the control mixture showed better properties, but one year later the results were opposite, asphalt containing RA and rejuvenator was more resistant to rutting. From the results of this experimental study the following was concluded: the amount of RA can be increased by using rejuvenator and the quality of such asphalt mixture is in most cases equal or even better than asphalt mixture made of virgin materials. By using RA we preserve nature, reduce usage of virgin raw materials, but it is cost effective only if recycling degree is high enough and is a daily practice.