With development of production processes in refineries production of bitumen is decreasing, as well as the quality of produced bitumen. On the market this brings increased demand for bitumen accompanied by the demand for additives to improve such low quality bitumen. Many different types of additives are used, but most commonly SBS is added. Usage of additives bring additional direct costs, due to market price of additives and indirect cost due to adjustments in the technological process as such as additional mixing device in bitumen tanks, elevated temperature of asphalt or prolongation in mixing time. A topic of our research was development low price asphalt additive from waste poly-methyl methacrylate filled with a fine dispersion aluminium trihydrate (PMMA/ATH). Additionally with paraffin wax it was used as modifying agents for 70/100 paving grade bitumen. With regard to performance of modified asphalt mixtures, it was found that both additives considerably reduce moisture susceptibility and formation of ruts. With laboratory tests and field trial we found that combined technology PMA (polymer modified asphalt) and WMA (warm mix asphalt) technologies resulted in optimized production and excellent performance of pavement material.
F.10 Improvements to an existing technological process or technology
COBISS.SI-ID: 5378330Removed asphalt layers (reclaimed asphalt-RA) are usually re-used as a supplement to new mixtures of the cold or hot process. The most common is the re-use of old asphalt in hot process "mix and plant." There are different procedures to add the old asphalt, depending on the equipment of asphalt plants. In Slovenia, the asphalt plants adds to the fresh materials from 5% to 30% of the old asphalt. On the asphalt plant Podutik was carried out trial production of asphalt mixture AC 16 surf B 70/100 A4 containg 50% RA and rejuvenator STORBIT. To the fresh material was added upto 50% of the old asphalt, that is more than usual in Slovenia. Produced asphalt mix has been built -in on a trial field, which consists of two parts. On one part is aspalt layer with RA and the second part, the same type of asphalt mix without RA. The temperature of asphalt mixture without additives was arround 170 ° C, a mixture prepared with RA and rejuvintor around 100 ° C. Lower temperature also means much less energy in the production of asphalt mixtures, and thus lower greenhouse gas emissions. When installing asphalt layers, this means lower emissions of bitumen fumes and vapors, and thus less harmful to the health of asphalt workers.
F.10 Improvements to an existing technological process or technology
COBISS.SI-ID: 5378586Asphalt is material that can be almost entirely recycled. But reclaimed asphalt (RA) contains aged binder, which limits the reuse of RA. In our study we increased the rate of recycled asphalt by adding rejuvenator containing paraffin. We investigated the effect of rejuvenator on laboratory and in plant prepared samples of asphalt mixture. In laboratory we prepared samples with different percentage of RA (0%, 10%, 30%, 50%) and rejuvenator. In asphalt plant we prepared asphalt mixture with highest amount of RA and rejuvenator and control mixture without RA. On samples we 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 TSRST method, but are less resistant to compaction and less sensitive to water than control mixture. For comparison of long term behaviour we conducted wheel tracking test on mixtures built in test field. A week after paving, the control mixture showed better properties, but a year after the results were opposite, asphalt containing RA and rejuvenator was more resistant to rutting. From the results of this experimental study we can conclude the following: 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 daily practice.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 5414938