Properties of asphalt mixtures after ageing are fundamental parameters in determining longterm performance (e.g. durability) of these materials. With increasing popularity of reduced temperature mixtures, such as warm-mix asphalt, WMA, the question remains how a reduction in short-term ageing affects the properties after long-term ageing of bituminous materials. This paper aims to improve our understanding of the effect of asphalt manufacturing temperature on ageing and the resulting mechanical properties of bituminous binder by studying the effect of short-and long-term ageing of different bitumen samples as a function of short-term ageing temperatures. For this purpose, round robin experiments were conducted within the RILEM technical committee (TC) 252 chemo-mechanical characterisation of bituminous materials by 10 laboratories from 5 countries using four binders of the same grade (70/100 pen) from different crude sources. The short-term ageing was carried out using the standard procedure for rolling thin film oven test (RTFOT), but varying the temperatures. Long-term ageing was carried out using the standard procedure for pressure aging vessel (PAV) in addition to RTFOT. For the mechanical characterisation, rheological data were determined by using the dynamic shear rheometer (DSR) and conventional tests, with needle penetration and softening point using the ring and ball method. The results show that although different short-term ageing temperatures showed a significant difference in the mechanical properties of the binders, these differences vanished after long-term ageing with PAV.Keywords: bitumen; DSR; long-term ageing; short-term ageing; asphalt; RTFOT; PAV
IntroductionAs an organic material, bitumen undergoes changes in its mechanical characteristics, chemical composition and microstructure due to environmental effects over its lifetime (Glotova, Gorshkov, Kats, Shapiro, & Yureva, 1980;Lee, Tia, Ruth, & Page, 1997;Mills-Beale et al., 2012;Yao, Dai, & You, 2015). Loss of volatile components at elevated temperatures and oxidation are two main factors for these changes. In terms of mechanical properties, bitumen tends to become stiffer, more elastic and brittle over time.
Road Materials and Pavement Design109 SARA (saturates, aromatics, resins and asphaltenes) fractions can be observed with an increasing amount of asphaltenes and decreasing amount of aromatics over time Lu & Isacsson, 2002). These changes are generally summarised under the term "ageing". Bitumen ageing can be split up into short-term and long-term ageing. In the case of hot mix asphalt, short-term ageing occurs during asphalt mix production, transport and compaction at the construction site, all of which happens within hours. It is characterised by relatively high temperatures ( > 130°C) and thus, high oxidation rates. Long-term ageing occurs in asphalt pavements in the field as a result of exposure to traffic and climatic conditions during its service life. Compared to short-term ageing, long-term ageing is a slow oxidation process tha...