Improved Accelerated Ageing of Asphalt Samples in the Laboratory (original) (raw)

Refinement of Climate-, Depth-, and Time-Based Laboratory Aging Procedure for Asphalt Mixtures

Transportation Research Record: Journal of the Transportation Research Board, 2020

This paper refines the oxidation kinetics-based approach originally proposed in the NCHRP 09-54 project to determine the laboratory aging durations at 95°C that best reflect the effects of time, climate, and depth on loose asphalt mixtures. Aging durations that match the field aging at various pavement depths were determined in this study for asphalt mixtures, including warm-mix asphalt (WMA), polymer-modified asphalt (PMA), and reclaimed asphalt pavement (RAP). Here, the laboratory aging durations were used to calibrate a climatic aging index to prescribe the laboratory aging duration, given hourly pavement temperature history obtained from Enhanced Integrated Climatic Model analysis of the Modern Era Retrospective-Analysis for Research and Applications, Version 2 weather data. The recalibrated procedure determines the required laboratory aging durations with reasonable accuracy for virgin hot-mix asphalt (HMA) and WMA mixtures. From the recalibrated results, no variations were fou...

Climate-, Depth-, and Time-Based Laboratory Aging Procedure for Asphalt Mixtures

Journal of the Association of Asphalt Paving Technologists, 2018

Aging causes asphalt pavement materials to stiffen and embrittle, which leads to a high cracking potential. A practical and accurate laboratory conditioning procedure that can simulate long-term aging of asphalt concrete for performance testing and prediction is required in order to integrate the effects of aging in pavement performance prediction models and other mechanistic design and analysis methods. Recent studies have suggested that loose mix oven aging at 95°C is the most promising long-term aging method to simulate field aging. This study has developed a means to determine laboratory aging durations for asphalt mixtures that best reflect the time, climate, and pavement depth for a given pavement location in the United States. A rigorous kinetics model together with laboratory experimental results demonstrate that the laboratory aging duration that is needed to match a given field condition is independent of material-specific kinetics. Project-specific laboratory aging durations that match field aging at various pavement depths were determined for a broad set of materials. The project-specific aging durations were used to calibrate a kinetics-derived climatic aging index (CAI) that was then used to determine the laboratory aging duration to match field aging at any location of interest. The CAI-determined aging durations at 95°C were used to generate aging duration maps for the United States for three field ages (4 years, 8 years, and 16 years) to match field aging at three depths (6 mm, 20 mm, and 50 mm).

Characterisation of ageing processes on the asphalt mixture surface

Road Materials and Pavement Design, 2014

Aging of asphalt binders leads to damage on pavements, due to changes in their rheological behavior and in the binder composition. A hardening of the asphalt can be observed, mainly caused by the oxidation of the asphalt binder itself. Oxidation rate is influenced by temperature, ultraviolet radiation and intrinsic characteristics of materials. In order to be characterized, the binder is extracted from the field-aged asphalt cores that use to have several centimetres in thickness. The aging process, however, depends on the access of oxygen into the field core which varies with the distance from the pavement surface. In order to know the aging conditions of the pavement surface (only) and to evaluate their influence on the adhesion characteristics, it is necessary to recover the surface asphalt binder. Only the surface binder is exposed to ultraviolet rays and weathering. A new test method has been developed in this work. It is based on the asphalt binder recovery from the upper part of the asphalt mixture layer. This method was validated by the infrared spectrometry through comparison with the neat asphalt binder (aged and not aged) and with the conventional extraction. In addition, an accelerated aging protocol was developed with the use of a climate chamber comprised of brightness settings, and moisture and weather conditioning, to relate to the French climate. The aging results obtained in the laboratory and in the field were compared using the same test method. This comparison allowed the establishment of an accelerator factor with respect to the increase of sulfoxide and carboxyl groups. This study provides a better understanding of the influence of aging on the skid resistance and the ability of the material to resist to polishing.

Characterization of aging processes on the asphalt mixture surface

HAL (Le Centre pour la Communication Scientifique Directe), 2012

Long-term ageing of asphalt mixtures

Road Materials and Pavement Design, 2017

Ageing of asphalt mixtures occurs during production and construction and continues throughout the service life of the pavement. Although this topic has been studied extensively, recent changes in asphalt mixture components, production parameters, and plant design have raised a need for a comprehensive evaluation that considers the impacts of climate, aggregate type, recycled materials, WMA technology, plant type, and production temperature. In this study, field cores were acquired from seven field projects at construction and several months afterwards, and raw materials were also collected for fabricating laboratory specimens that were long-term oven aged (LTOA) in accordance with selected protocols. The resilient modulus and Hamburg wheel tracking tests were conducted on both specimen types to evaluate the evolution of mixture stiffness and rutting resistance with ageing. The concepts of cumulative degree days and mixture property ratio were proposed to quantify field ageing and its effect on mixture properties. Test results indicated that the LTOA protocols of two weeks at 140°F (60°C) and five days at 185°F (85°C) produced mixtures with equivalent in-service field ageing of 7-12 months and 12-23 months, respectively, depending on climate. Finally, among the factors investigated in the study, WMA technology, recycled materials, and aggregate absorption exhibited a significant effect on the long-term ageing characteristics of asphalt mixtures, while production temperature and plant type had no effect.

The Combined Effect of Ultraviolet Irradiation and Temperature on Hot Mix Asphalt Mixture Aging

Sustainability

Reliable accelerated simulation of asphalt aging is of significant interest to asphalt researchers and pavement practitioners alike. However, current laboratory aging protocols are either based on binder aging rather than mixture aging or use dry ovens to heat asphalt mixtures, omitting the important effects of UV radiation. Binder aging cannot take into account the interactions between the binder and aggregate phases during aging, while the omission of UV radiation ignores an important catalyst in the aging process. In this study, a comparison of the effect of conventional thermal oven aging to the combined effect of heat and ultraviolet irradiation on the resilient modulus and surface texture of dense-graded asphalt field cores and gyratory-compacted samples was undertaken. Significantly higher rates of modulus increase with aging time were measured for the samples aged by both heat and ultraviolet irradiation. The gyratory-compacted samples showed more realistic results in terms ...

A review of asphalt and asphalt mixture aging

Revista Ingenieria E Investigacion, 2013

This paper presents an extensive review of the pertinent literature regarding asphalt and asphalt mixture Aging. Aging affects flexible pavement performance and is produced by intrinsic and extrinsic variables as well as exposure time. Intrinsic variables include asphalt and aggregate properties, a mixture's asphalt content, binder film thickness and air void content; extrinsic variables are associated with production (short-term aging) and exposure to environmental field conditions (long-term aging). Taken together, both variables demonstrate that aging results from three distinct mechanisms: volatilisation, oxidation and steric hardening. Temperature, pressure and photo degradation treatments are used to simulate aging in the laboratory and empirical and semi-empirical models are created to represent and study aging. Aging increases asphalt complex modulus and decreases the phase angle. Mixtures become stiffer while fatigue life becomes reduced. Carbonyl and sulfoxide group formation in asphalt are often studied as such chemical changes show oxidation in aged asphalts. The prevailing models used to predict asphalt aging are discussed, though more comprehensive research into asphalt aging is still needed.

A review of asphalt and asphalt mixtures aging

Evaluation of Short-Term Aging Protocol for Asphalt Mixtures

Applied Sciences, 2019

Asphalt mixtures are subjected to short-term aging during the production, placement, and compaction processes. Proper evaluation of asphalt pavement performance relies on the accurate characterization of asphalt mixtures during the design stage. In this study, three different loose asphalt mixtures often used in Qatar were evaluated to develop a laboratory short-term aging procedure. Sample mixtures 1 and 3 were collected from a construction site, while mixture 2 was obtained from an asphalt plant. Virgin aggregates and binders were also collected to reproduce the mixtures in the laboratory. Laboratory-produced mixtures were conditioned at 135 °C using various time durations. The mechanical properties of laboratory-produced mixtures were compared to those of mixtures produced on site. The results of the mechanical and binder testing demonstrated that the proper short-term aging protocol for asphalt mixtures often used in road construction in the State of Qatar would involve heating ...

Evaluation of asphalt mixture laboratory long-term ageing methods for performance testing and prediction

Road Materials and Pavement Design, 2016

Ageing has long been recognised as a major distress mechanism for asphalt concrete and, by extension, asphalt pavements. Ageing causes the material to stiffen and embrittle, which leads to a high potential for cracking. Although a significant amount of effort has been placed on understanding the ageing process of asphalt binder, less effort has been put forth to develop laboratory ageing procedures for producing aged mixture specimens for performance testing. An optimal laboratory conditioning procedure to simulate long-term ageing for performance testing and prediction is required in order to integrate the effects of long-term ageing in pavement prediction models and other mechanistic design and analysis methods. In this study, oven ageing and pressure ageing vessel ageing are applied to both loose mix and compacted specimens in order to evaluate and select an ageing method to simulate long-term ageing for performance testing and prediction. The selected method must be able to maintain specimen integrity in order to be used for performance testing and prediction. Efficiency, practicality, and versatility also are considered in evaluating the ageing methods. The results demonstrate that loose mix ageing in an oven is the most promising ageing method to produce mixture specimens for performance testing in terms of efficiency, specimen integrity, versatility, and cost.

Improved Accelerated Ageing of Asphalt Samples in the Laboratory (original) (raw)

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