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Ageing phenomenon plays a key role on asphalt mixtures performance and durability, being susceptible to diverse designing factors that can be adjusted during both design and industrial manufacturing process. Thus, this paper focused on assessing the effect of main designing factors on the ageing rate of asphalt mixtures. It was evaluated the influence of type and quantity of bitumen, the dosage of filler and the impact of mineral skeleton on the ageing process of a gap-graded mixture, when ranging such parameters within acceptable values due to possible slight changes during manufacturing process. Results denoted that all factors presented a relevant impact on the range of change in material stiffness, deformation susceptibility and resistance to fatigue cracking due to ageing process. According to the results, the type of bitumen and filler content were seen as the most influential factors while the quantity of sand presenting lower levels of variation due to ageing, obtaining a more durable and resistant material when using a denser mineral skeleton. [ABSTRACT FROM AUTHOR]

This article studies the phenomenon of ageing in asphalt mixtures, considering the impact of temperature, time and pressure via laboratory techniques, compared with roadway samples. In particular, the ageing of two mixtures was analysed, manufactured with a high voids content and with two different modified binders (SBS polymer and crumb rubber), while comparing results with those obtained for cores from a highway using similar mixtures in surface layer. The stiffness and fatigue cracking life of the mixtures were assessed, after different ageing periods at diverse temperature and pressure levels. Results demonstrated that the laboratory ageing simulation of asphalt mixtures strongly depended on the studied parameters. Long ageing periods (in this study 9 days) at a high temperature (135°C for the cases analysed in this paper) was required in order to reproduce a marked ageing impact, while providing the ability to differentiate the susceptibility of ageing of different materials. [ABSTRACT FROM AUTHOR]

Asphalt pavement properties (strength, durability, bearing capacity, etc.) are considerably affected by environmental conditions. Because of this fact, regions with severe climates (high thermal gradients, abundant precipitation, presence of freeze-thaw cycles, solar radiation, etc.) have serious problems in maintaining the functional integrity of these infrastructures. Thus, it is necessary to develop new materials that could extend the service life of these pavements without increasing the construction costs. Accordingly, the present paper studies the improvement of the mechanical performance of high-modulus asphalt mixtures through the addition of acrylic fibers, for their use under severe environmental conditions. For this purpose, different tests were carried out [thermal stress restrained specimen test, immersed wheel-tracking test, freeze-thaw sensitivity test, and UGR-FACT (University of Granada-Fatigue Asphalt Cracking Test)] under variable conditions (simulating cold and hot scenarios). The results show that the use of acrylic fibers improves the mechanical behavior of high-modulus asphalt mixtures (at high and low temperatures, as well as under the presence of water and ice), and could thus be considered an interesting alternative for extending the service life of asphalt pavements in severe climates. [ABSTRACT FROM AUTHOR]