Influence of F-T Synthetic Wax on Asphalt Concrete Permanent Deformation

Abstract

The paper presents the results of the study of the effect of a Fischer-Tropsch (F-T) synthetic wax on the resistance to permanent deformation of the AC 11S asphalt concrete. The synthetic wax was dosed at 1.5%, 2.5% and 3.5% by weight of bitumen 35/50. The compaction temperatures were 115ºC, 130ºC and 145ºC. The criteria adopted for measuring the resistance to permanent deformation included the following parameters: stiffness modulus at 2, 10 and 20ºC, permanent deformation (RTS), fatigue life determined using the indirect tensile fatigue test (ITFT) and resistance to rutting (WTSAIR, PRDAIR). The test results confi rmed the positive infl uence of F-T synthetic wax on enhancing the permanent deformation resistance of asphalt concrete placed at lower compaction temperatures compared to that of standard asphalt concrete compacted at 140ºC.

Structuring role of F-T synthetic wax in bitumen

“…2). The ratio of the binder elastic behaviour to the strain plastic behaviour increases proportionally to the temperature drop [20]. At a temperature of 25…”

“…• C and as a result aggregate grains are coated with bitumen binder at temperatures [20][21][22][23][24][25][26][27][28][29][30] • C lower than the traditional temperature of approximately 165…”

“…The most commonly accepted modifier used to improve the properties of road bitumens, increase their workability and ensure proper performance of the pavement upper layers in winter low temperatures and summer high temperatures is the styrene-butadiene-styrene (SBS) block copolymer [1][2][3]. Modifiers of this type are used within the traditional range of mix production and placement temperatures [4].…”

Resistance to Permanent Deformation of the Tla-Modified Mastic Asphalt Mixture Based on Static and Dynamic Indentation

“…The 35/50 base bitumen was modified with TLA quantities from 0% to 20% (relative to the weight of the base bitumen), with a step of 10%. Such proportions of TLA to base bitumen were assumed based on available studies [7][13][20] [29] and the initial research of the authors [1][9] which implied that a 10% step in the quantity of TLA results in a noticeable difference in the properties of the final binder. The addition of more than 20% leads to excessive stiffness of the binder, which can negatively affect the low-temperature performance of the MA mixture.…”

“…To make the mastic asphalt mixture resistant to permanent deformation, products that "harden" bitumen are used, such as waxes, polymers and natural asphalts [7]. In the latter case, Trinidad Lake Asphalt (TLA) is often applied.…”