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Bitumen is a commonly used material for road construction. According to environmental regulations, vegetable-based materials are applied for binder modification. Fluxed road bitumen containing a bio-flux oxidation product increases the consistency over time. The efficiency of crosslinking depends on the number of double bonds and their position in the aliphatic chain of fatty acid. The main goal of this paper was to examine the structural changes taking place during hardening bitumen with bio-flux additives. Two types of road bitumens fluxed with two different oxidized methyl esters of rapeseed oil were used in this study. Various chemical and rheological tests were applied for the fluxed-bitumen at different stages of oxygen exposure. The oxidation of rapeseed oil methyl ester reduced the iodine amount by about 10%-30%. Hardening of the fluxed bitumen generally results in an increase of the resins content and a reduction of the aromatics and asphaltenes. In the temperature range of 0 • C to 40 • C, bio-flux results with a much higher increase in the phase angle than in temperatures above 40 • C in the bitumen binder. The increase in the proportion of the viscous component in the low and medium binder temperature is favorable due to the potential improvement of the fatigue resistance of the asphalt mixture with such binders.

Bitumen fluxes of vegetable origin Summary-Methods of preparation of bitumen fluxes from rapeseed and linseed oil methyl esters were developed. The methods consist in the catalytic oxidation of vegetable oil methyl esters in the absence or presence of peroxides as the accelerators. The products obtained can be used as environmentally friendly bitumen fluxes. The rapeseed oil methyl ester has to be oxidized at elevated temperature in the presence of a catalyst. Linseed oil methyl ester does not need pre-oxidation before mixing with bitumen, but mixing with the catalyst is necessary. Contrary to conventional bitumen solvents, the fluxes are not volatile and have an ignition point of approximately 200 o C, so they do not raise safety problems. The hardening of the fluxed bituminous binder is going not by evaporation of the flux but by oxidative polymerization in the presence of a catalyst. The use of the fluxes let considerably reduce the mixing or spreading temperature of the binder, as well as the compacting temperature of the binder-aggregate mix.

Zmiany struktury chemicznej estrów metylowych kwasów t³uszczowych oleju rzepakowego podczas katalitycznego utlenienia w temperaturze 200 o C Streszczenie-Przeprowadzono utlenianie estrów metylowych kwasów t³uszczowych oleju rzepakowego w temp. 200 o C, w obecnooeci katalizatora kobaltowego. Podczas tego procesu przebiegaj¹ dwie konkurencyjne reakcje tworzenia siê oraz rozpadu nadtlenków i wodoronadtlenków powstaj¹cych jako produkty przejoeciowe. Po wyczerpaniu w surowcu najbardziej reaktywnych struktur z trzema i dwoma wi¹zaniami nienasyconymi, reakcja rozpadu nadtlenków staje siê dominuj¹ca, wskutek czego ich zawartooeae w produkcie maleje. Badania surowca i produktu metodami spektroskopii FT-IR i 1 H NMR oraz zmniejszenie wartooeci liczby jodowej potwierdzaj¹ zanik wi¹zañ podwójnych. Udzia³ struktur z trzema, dwoma i jednym wi¹zaniem nienasyconym zmniejszy³ siê po 25 h utlenienia odpowiednio o 98, 86 i 25 %. Sk³ad lotnych produktów utlenienia, w których obecne s¹ aldehydy, ketony, kwasy, alkany i alkeny, laktony a tak¿e alkilofurany, oewiadczy o utleniaj¹cym rozpadzie ³añcucha nienasyconych kwasów t³uszczowych. Zwiêkszenie ciê¿aru cz¹steczkowego o ok. 50 % dowodzi czêoeciowej oligomeryzacji cz¹steczek surowca. S³owa kluczowe: up³ynniacze asfaltu, estry metylowe kwasów t³uszczowych oleju rzepakowego, katalityczne utlenianie, produkty utlenienia, utleniaj¹ca oligomeryzacja. STRUCTURAL CHANGES IN RAPESEED OIL METHYL ESTER DURING CATALYTIC OXIDATION AT 200 o C Summary-Rapeseed oil methyl ester (Table 1) was oxidized at temp. 200 o C in the presence of cobalt catalyst. Two competitive reactions are going during this process: formation and degradation of peroxides and hydroperoxides being intermediate products (Scheme A). After depletion of the most reactive structures with three or two unsaturated bonds in the material, the reaction of peroxides' decomposition becomes dominant so their concentration in the product decreases. The substrate and product examinations by FT-IR (Fig. 2) and 1 H NMR (Table 2) as well as lowering of iodine value (Fig. 1a), confirm the double bonds decay. The content of structures with three, two or one unsaturated bond after 25-hour oxidation decreased about 98, 86 and 25 % respectively (Table 3). Composition of volatile products of oxidation (Table 4) (aldehydes, ketones, acids, alkanes and alkenes, lactones and alkylfuranes) confirms the oxidative decomposition of unsaturated fatty acids chains. An increase in molecular weight of about 50 % proves the partial oligomerization of substrate molecules (Fig. 1c).