1,721,061 research outputs found
Modeling of the rheological properties of asphalt binder and asphalt mortar containing recycled asphalt material
No full textThe use of recycled materials in asphalt pavements increased significantly over the years, determining well known environmental and economic benefits. Many research agencies and road authorities evaluated the impact of Recycled Asphalt Pavement (RAP) on pavement performance. Nevertheless, the mechanism governing the interaction between virgin asphalt binder and aged RAP binder is not well understood. In this paper, the effect of RAP on the rheological properties of asphalt binders and mortars is experimentally evaluated, and theoretically modeled with the objective of defining a relationship between the linear viscoelastic (LVE) properties of binders and those of the corresponding mortars.Three asphalt binder types, obtained by blending a hard and a soft binder at three different percentages, were mixed with three different contents of a Selected fraction of Recycled Asphalt Pavement, called SRAP, for preparing the asphalt mortar samples. Dynamic Shear Rheomether tests were performed on binders and mortars to determining the complex modulus over a wide range of temperatures and frequencies. The rheological properties of the compound of virgin and RAP binder were evaluated by using a new approach based on a modified version of the Nielsen model, avoiding the extraction and recovery method.The results were then modelled by using the analogical 2S2P1D model, consisting of one spring, two parabolic and one-dashpot elements combined in series and then assembled together with a second spring in parallel. Based on test results, a simple experimental relationship between the characteristic times of the binder and the percentage of RAP in the mortar was found
Energy dissipation in asphalt mixtures observed in different cyclic stress-controlled fatigue tests
No full textExperimental evaluation of crack propagation in asphalt mixture based on photoelasticity
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Laboratory study on asphalt mixture modified by polyacronitrile fibres and reclaimed asphalt planings
No full textn this laboratory study, combined effects of polyacronitrile fibres and reclaimed asphalt planings on performance properties of asphalt mixtures were investigated. Performance properties of six asphalt mixtures in total were comparatively analyzed, always considering a standard mix design concept for asphalt binder courses. Three asphalt mixtures were prepared with fresh materials only: two asphalt mixtures were produced without incorporating fibres, one using unmodified plain binder of the type 50/70 Pen Grade (in the following used as reference mixture and therefore identified as Ref.), the other one using polymer modified binder of the type 40/100-65 Pen Grade (identified as PmB). The third one was a fibre reinforced asphalt mixture (FRAM), composed of 50/70 Pen Grade binder, and 0.15% by total weight of the asphalt mixture of polyacronitrile fibres added directly in the drum to the aggregates. In addition, three more asphalt mixtures were prepared similarly, but 50% of the total mass was replaced by recycled material originating from reclaimed asphalt planings (RAP). These three mixtures containing RAP were identified as Ref.+RAP, PmB+RAP, and FRAM+RAP. All six asphalt mixtures were subjected to performance tests: wheel tracking tests were conducted in the high temperature range to study permanent deformation resistance, indirect tensile tests were conducted at intermediate temperatures to study fatigue resistance, and thermal stress restrained specimen tests were conducted at low temperatures to study resistance to thermal cracking. Test results indicate that asphalt mixture modification by polyacronitrile fibres and reclaimed asphalt planings results in acceptable performance properties, and potentially improves high and intermediate temperature properties
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