Showing papers by "Hugo Manuel Ribeiro Dias da Silva published in 2011"
01 Sep 2011
TL;DR: Portuguese Foundation for Science and Technology (FCT) in the scope of the Strategic Project UI 4047 2011-2012 as mentioned in this paper, has published a survey of the state-of-the-art research in the field of Artificial Intelligence.
Abstract: Portuguese Foundation for Science and Technology (FCT) in the scope of the Strategic Project UI 4047 2011‐2012
6 citations
11 Oct 2011
6 citations
12 Sep 2011
TL;DR: In this article, the utilization of a used motor oil as a rejuvenator was evaluated and the optimal amount of oil was determined by conventional bitumen tests, using the achievement of a bitumen with a penetration grade above, as the selection criterion for the definition of the oil.
Abstract: The environmental and economic benefits of using Reclaimed Asphalt Pavement (RAP) material in hot mix asphalt (HMA) applications could be pushed up to the limit, by producing totally recycled HMAs (100% RAP), but the performance of this alternative must be satisfactory. In fact, these mixtures could possibly present a lower performance due to the behaviour of the aged binder, which loses its lighter fractions with time. In order to improve the mixture properties, a binder rejuvenator should be used. Thus, in the present study, the utilization of a used motor oil as a rejuvenator was evaluated. This would allow the modification of the aged binder, restoring some of its original properties and promoting an adequate performance of the mixture. The optimal amount of oil was determined by conventional bitumen tests, using the achievement of a bitumen with a penetration grade above, as the selection criterion for the definition of the amount of oil. Once the amount of rejuvenator (oil) was defined, laboratory specimens were prepared and tested for water sensitivity, permanent deformation, stiffness and fatigue, in order to confirm that the totally recycled mixture will perform as good as a conventional mixture used for comparison purposes.
3 citations
01 Jun 2011
TL;DR: In this paper, the authors evaluated the effectiveness of rejuvenator agents to improve the performance of recycled asphalts and the properties of their aged binders in hot mix asphalt applications.
Abstract: The use of reclaimed asphalt pavement (RAP) in road related applications helps road authorities to achieve their goal of a sustainable road transport system by reducing waste and resource consumption. The use of RAP in hot mix asphalt applications has environmental and economic benefits, and the performance could also be satisfactory. However, problems of workability and durability can be also observed, especially in recycled asphalts with high RAP contents. Thus, the objective of this paper is to evaluate the merit of some rejuvenator agents to improve the performance of recycled asphalts and the properties of their aged binders. The rejuvenator agents used in this study were a commercial product and one used engine oil. Several blends of oxidized bitumens with the referred rejuvenator agents were prepared in order to simulate mixtures with 100 per cent RAP. These binders were characterized through their basic properties (Pen, R&B) and dynamic viscosity at high temperatures. Then, some recycled asphalts were produced with the best previously observed combinations, and their workability, durability and stiffness performance was assessed. The main conclusion of this paper is that the rejuvenator agents enable the use of high RAP contents on recycled asphalts with better performance.
1 citations
01 Jun 2011
TL;DR: In this article, the properties of a bituminous mixture that combines the effects of a FischerTropsch (FT) wax with a surfactant were studied and compared to those of a conventional hot mix asphalt.
Abstract: In the last few years several additives have been developed for the production of Warm Mix Asphalts (WMA). Some additives do not demand significant modifications to be made to the asphalt plant, namely those that are added to the binder. Previous work carried out by the authors using synthetic waxes and surfactants showed that both types of additive can be used in the production of WMAs. However, it was observed that waxes have a significant effect on the increase of the resistance to permanent deformation of the mixture while surfactants are more effective on the temperature reduction. Thus, in this paper the properties of a bituminous mixture that combines the effects of a FischerTropsch (FT) wax with a surfactant were studied and compared to those of a conventional hot mix asphalt. In this work, the properties of a 50/70 pen bitumen mixed with different percentages of the additives were analyzed, the production temperature was defined, and the fundamental properties of the mixture (moisture sensitivity and resistance to permanent deformation and fatigue) were obtained. The results obtained showed that the combined action of the additives allows a significant temperature reduction without compromising the mixture properties.
1 citations