The Evaluation of Asphalt Mixture Mastic as an Aging Indicator (original) (raw)

Rheological Characterization of Aged Asphalts

CT y F - Ciencia, Tecnologia y Futuro

The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. Rheological behavior was evaluated using the new specifications of SHRP technology in the Brookfield and DSR rheometers to determine viscosity, Shear Stress, Shear Rate, Dynamic Share Modulus and other related variables. The measurements were made using different temperatures and load times.

A method to estimate the rheological properties of aged asphalt binders without actually aging them

Aroon Shenoy, 2002

Asphalt binder stiffens due to aging during the mixing and lay down operations as well as during the service life of the pavement. The aging processes in the field have been simulated in the laboratory through the use of accelerated test procedures and tracked through rheological characterization of the aged asphalts. However, the laboratory aging procedures along with the rheological characterization of the aged samples are time-consuming processes. Some researchers have been seeking methods to shorten the time involved in generating this information, while others have been suggesting improvements in the test procedures to get reproducible and reliable data, and still others are attempting to find the procedures that would give information in the laboratory that is closer to the reality in the field. In all cases, it is the rheological properties of the aged binders that are used for characterizing the extent of aging. The present work is a step in the same direction but chooses a different approach. A method is proposed to shorten the time involved in generating the information on the aged binder rheology. The suggested procedure aids in estimating the rheological properties of aged asphalts without actually going through the aging process. In order to establish the procedure, rheological data on unaged asphalts are compared with rheological data on aged samples after the Rolling Thin Film Oven Test (RTFOT) and Pressure Aging Vessel (PAV)-aging. It is shown that estimates of the specification temperatures based on the high and intermediate temperature rheological properties of the aged asphalts can be obtained without actually aging the binders in the laboratory. By eliminating the laboratory aging procedures to obtain rheological properties of the aged asphalts, there is a great saving in time and the information is obtained rapidly.

Laboratory investigation of asphalt mixture aging

Proceedings of 6th Eurasphalt & Eurobitume Congress, 2016

The rheological properties of asphalt binders change with time. Asphalt mixtures get stiffer and more prone to fatigue cracking with aging. This study is a part of a comprehensive study undertaken to develop improved protocol for asphalt mixture conditioning in the laboratory to simulate asphalt mixture aging due to the climate conditions in the State of Qatar. In this study, asphalt mixtures were prepared by mixing Gabbro base aggregate with Pen 60-70 binder. Initially, mixtures were conditioned at short-term aging temperature of 135°C for different time periods (2, 4 and 6 hrs). Long-term aging was completed after compaction of test specimens to the desired air void level of 7 ± 0.5% by using Superpave gyratory compactor. Three different long-term aging temperatures (i.e., 75, 85 and 95°C) and four different aging levels (0, 2, 6, and 10 days) were evaluated in this study. Then, the specimens were tested in an AMPT to determine dynamic modulus and phase angle. Results of this study were presented by plotting a series of mastercurves obtained from performance testing of the aged specimens. The results showed that aging temperature and duration have significant effects on the viscoelastic properties of asphalt mixtures.

Effects of fillers on the rheological/mechanical performance of mastics/asphalt mixes

2013

This paper summarises the effects of four different fillers on the rheological properties of mastics and mechanical properties of asphalt mixtures produced with these four different types of added fillers. The main aim of the study is to evaluate rheological properties of the mastic that control the asphalt performance (i.e. rutting, fatigue cracking and thermal cracking). The second objective of the study is to evaluate some of the mechanical properties of the asphalt mixtures produced with the studied fillers as well as the optimum bitumen content for a certain aggregates, grading curve and filler content. Therefore, in addition to a preliminary characterization of the fillers based on the evaluation of the Specific Surface Area (SSA) and Rigden voids, the study is divided in two main sections. Firstly four different mastics have been prepared in order to conduct Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) tests and therefore obtain information about the rheolog...

Correlation between rheology and chemical composition of aged polymer-modified asphalts

Construction and Building Materials, 2014

The study explores correlation between chemistry and rheology of aged PMA. Severity of aging procedure, polymer content and its concentration affect PMA viscosity. Complex shear modulus can be fairly estimated from chemical composition elucidated by ATR FT-IR. Polymer concentration can be backcalculated from absorbance spectrum of PMA.

USE OF DYNAMIC MECHANICAL ANALYSIS TO PREDICT DAMGE IN ASPHALT MASTIC

ICAR Project 203 developed a viscoplastic model to describe the response of asphalt mixtures under load. The model accounts for the contribution of the aggregate matrix and for the ability of the asphalt mastic to resist damage. This paper describes a method to characterize the viscoelastic properties and damage characteristics of asphalt mastics using dynamic shear rheometer measurements and dynamic mechanical analysis (DMA). Dynamic mechanical analysis results are used to define the rate of damage that occurs in the mastic under repeated torsional loading and the amount of damage the mastic can withstand before failure. The damage properties will replace x-ray computerize tomography (CT) now being used in the ICAR viscoplastic performance model developed in Project 203. Data demonstrate that the DMA method of analysis is very sensitive to the type and amount of mineral filler (smaller than 74 µm) that is combined with the asphalt cement.

Determination of Rheological Properties of Bio Mastic Asphalt

American Journal of Engineering and Applied Sciences, 2008

Due to the high oil prices the price of asphalt binder has increased tremendously. This scenario has warranted demand for higher viscosity cheaper asphalt for pavement construction. A study was conducted to take advantage of the Empty Fruit Bunch (EFB) of Date and Oil Palm trees (which are considered as waste) to produce cellulose fiber to be used as additives in the asphalt binder. If these EFB's could be beneficially utilized in any application, it would reduce the load on the nation's landfills and at the same time reducing the cost of road construction. A total of 11 blends were prepared that consisted of 5 blends with date palm fiber, 5 blends with oil palm fiber and one control sample that contained no fibers. The samples were evaluated using Dynamic Shear Rheometer (DSR) equipment in accordance with the superpave Strategic Highway Research Program (SHRP) requirements. The neat asphalt binders (Unaged), Rolling Thin Film Oven (RTFO) aged and Pressure Ageing Vessel (PAV) samples were then measured for phase angle, shear strain and complex shear modulus and then evaluated in accordance with SHRP requirements. The results indicated that the fibers enhanced the rheological performance of Bio Mastic Asphalt (BMA) blends. The control sample which was categorized as PG58 was enhanced to PG76 with 0.375% date palm fiber. The oil palm has also improved the blend up to PG70 with 0.3% oil palm fiber.

Characterization of aging processes on the asphalt mixture surface

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

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.

Effect of long-term ageing on the rheological properties of rejuvenated asphalt binder

Road Materials and Pavement Design, 2019

Recycled asphalt products are increasingly being used in asphalt concrete pavements to improve pavement sustainability. Asphalt recycling, while it is undoubtedly an environmentally sustainable practice, includes asphalt binder that is already oxidised. Aged binder is highly brittle and becomes a driving factor for cracking related distresses. As a result, use of recycled materials can have a significant negative impact on pavement performance, specifically when used in increased amounts and cold climatic conditions. In order to improve the performance of asphalt concrete mixtures with recycled materials, rheological properties are changed by adding rejuvenators. In asphalt industry, rejuvenators are either used at an initial virgin state of the binder to reduce mix ageing or blended at a later stage in recycled materials to improve the properties of aged mix. The current study focuses on evaluating the performance of asphalt mixes prepared by blending rejuvenators in already aged binders. Virgin PG 64-22 binder was aged using RTFO and PAV and further mixed with three different kinds of rejuvenators namely Hydrolene 90T, Kendex@ME, and Hydrogreen S at 3%, 6% and 9% by weight of the total binder. To study the behaviour of rejuvenated asphalt binder samples over a long period of time, mixed asphalt samples were then aged for 5, 10, 15, 20, 40 and 60 h in the PAV. Frequency sweep tests were conducted to characterise binder rheology, and parameters such as Glower-Rowe, crossover frequency, and Superpave rutting parameter were calculated. A comparative analysis was carried out to determine the impact of increased ageing and rejuvenator addition in varying amounts on the performance of asphalt mixes. A significant correlation was found out between the types of rejuvenator used in different dosages and the level of ageing in the asphalt binder.