Search results for "Asphalt"
showing 10 items of 151 documents
The effect of prolonged storage time on asphalt rubber binder properties
2019
Abstract This study wants to provide fundamental understanding of prolonged storage time on asphalt rubber binder properties by performing an investigation on the variation of conventional properties, rheology and morphology of four asphalt rubbers maintained at 180 °C in low shear for different digestion/storage times up to 48 h. The analysed asphalt rubbers were manufactured by combining two different asphalt binder grades, pen 35/50 and pen 50/70, with both cryogenic and ambient crumb rubber. Results have shown that keeping asphalt rubber agitated at the above mentioned processing conditions, up to 48 h, is significantly detrimental when an ambient crumb rubber is used, while it seems no…
The effects of laboratory ageing on rheological and fracture characteristics of different rubberised bitumens
2018
Ageing of bituminous materials can result in loss of the durability of a flexible pavement. Using rubberised bitumens can enhance pavement performance while at the same time it solves a serious waste disposal problem. Combining Warm Mix Asphalt (WMA) additives with rubberised bitumens reduces the difficulties associated with the production of asphalt mixtures using this modified binder. This work was conducted to study the effect of ageing using fundamental parameters based on performance, i.e., CTOD and Glover-Rowe parameters have been related to pavement cracking. Different unmodified bitumens and rubberised bitumens were short-term aged using the Thin Film Oven Test (TFOT) and long- term…
Fatigue and Healing Properties of Low Environmental Impact Rubberized Bitumen for Asphalt Pavement
2017
The addition of recycled tyre rubber as a modifier to enhance the mechanical properties of bitumen has proven to provide asphalt mixtures with better mechanical performance. However the rubberised bitumen presents the limitation of requiring higher manufacturing and compaction temperatures. This could be solved by subjecting the tyre rubber to sort of pre-treatments such as: Adding warm-mix additives and/or using partial devulcanisation. These solutions have the potential of lowering the overall environmental impact of the asphalt pavement, however it is still not clear whether these can be detrimental for the rubberized asphalt binder mechanical properties. This paper investigates the effe…
A new procedure to determine the rheological properties of RAP binder and corresponding bituminous blends
2017
Abstract In this paper, a new and simple approach to estimate the rheological properties of Reclaimed Asphalt Pavement (RAP) binder is proposed to overcome the limitations of the conventional extraction procedure. This method is based on Dynamic Shear Rheometer tests performed on mortars composed of RAP fine fraction and virgin binder, together with a new back-calculation solution. The properties of the bituminous blends of virgin and RAP binders are obtained with a modified Nielsen model. The Voigt model is then successfully used to estimate complex modulus and phase angle of the RAP binder from the properties of the back-calculated binder blend. This procedure would prevent the need of RA…
Thermo-rheological analysis of WMA-additive modified binders
2020
AbstractThermo-rheological characteristics of unmodified and modified bitumen have significant impacts on the mechanical response of asphalt. This study investigates the impacts of an organic and a chemical Warm Mix Asphalt additive on bitumen thermo-rheological and mechanical characteristics. Modified binders with different concentrations of each additive were studied and analysed comparatively to a 40/60 penetration grade bitumen. Frequency sweep tests were performed at different ageing levels to characterise the Linear Viscoelastic properties. The multiple stress creep and recovery, linear amplitude sweep (LAS) and low temperature creep stiffness tests, together with the Glover–Rowe (G–R…
Linear viscoelastic properties of high reclaimed asphalt content mixes with biobinders
2017
The use of high Reclaimed Asphalt (RA) content mixtures together with binders produced from renewable resources (biobinders) is one of the current challenges in pavement engineering research. On the one hand, RA has been used for decades, but there are still some concerns about its performance, especially when high contents are used (>30%). On the other hand, biobinders are relatively new materials, which have to be deeply characterised and studied in order to develop good practices for their use. In this paper, linear viscoelastic properties of biobinders and bio-mixtures manufactured with high RA content and biobinders are analysed and discussed. High-modulus mixtures with 50% RA were…
Asphalt surface mixtures with improved performance using waste polymers via dry and wet processes
2017
"Published online: June 29, 2017"
Wide Angle X-ray Scattering as a Technique of Choice to Probe Asphaltene Hierarchical Structures
2020
Bitumens are composite systems extensively used in road pavements. Due to their complex nature, a rational understanding of the relationships between composition, structure and performances of these materials is still far from being achieved, so research attempting to shed more light in this field is required. Here, we exploit Wide Angle X-ray Scattering (WAXS) as a technique of choice to shed light on the bitumen structure at different length scales. Diagnostic fingerprints, characterizing the WAXS profile, are correlated to specific Bragg distances which can be reasonably attributed to the molecular and supramolecular aggregation taking place at various levels of complexity leading to the…
Time dependent viscoelastic rheological response of pure, modified and synthetic bituminous binders
2016
Bitumen is a viscoelastic material that exhibits both elastic and viscous components of response and displays both a temperature and time dependent relationship between applied stresses and resultant strains. In addition, as bitumen is responsible for the viscoelastic behaviour of all bituminous materials, it plays a dominant role in defining many of the aspects of asphalt road performance, such as strength and stiffness, permanent deformation and cracking. Although conventional bituminous materials perform satisfactorily in most highway pavement applications, there are situations that require the modification of the binder to enhance the properties of existing asphalt material. The best kn…
Evaluation of aging processes of petroleum asphalt cements by solid state electrochemical monitoring
2018
Abstract The changes in the chemistry of organosulfur compounds from asphalt cements during aging are studied using solid state voltammetry of immobilized microparticles. Five Brazilian asphalt cements were evaluated after three forced aging processes: Rolling Thin Film Oven Test (RTFOT), Pressure Aging Vessel (PAV) and SUNTEST. It was possible to identify the presence of thiophenes, sulfides and sulfoxides in the different samples and the reactional changes during the aging processes were proposed. Voltammetric data, supported by ATR-FTIR spectroscopy, indicate that aging asphalts involve the increase of the proportion of sulfoxide and thiophene components and that polythiophene compounds …