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The current test methods for measuring the fatigue cracking resistance of asphalt mixtures involve many steps which are time-consuming and costly. On the other hand, asphalt binder testing is less time-consuming and more accessible than mixtures testing. Therefore, if the routinely measured properties of the asphalt binder and volumetric properties of the mixtures can be used to predict cracking resistance performance of mixtures, much effort to perform the mixtures testing of asphalt mixtures can be minimised. In this study, prediction models of mixture parameters calculated from the Semi-Circular Bending-Illinois Flexibility Index Test (SCB-IFIT) are developed using an experimental database including 42 mixtures that are short-term aged and 30 mixtures that are long-term aged mixtures. Based on the correlation results and the validation using a separate set of the mixture, the developed models of SCB parameters are found to provide reliable estimates of the flexibility index (FI), post-peak slope and fracture energy (Gf) of asphalt mixtures. The developed models are recommended for initial screening of mixture components (binder and mix variables) or estimating the cracking resistance of asphalt mixtures when testing is not feasible. They are not meant to totally replace the testing of the final selected mixtures. [ABSTRACT FROM AUTHOR]

The linear amplitude sweep (LAS) test is useful for evaluating the fatigue of asphalt binders. In this paper, the combined effects of strain and temperatures are investigated, and a method for estimating binder fatigue behaviour is introduced at different temperatures from limited measurements. LAS tests were conducted on several different PG-grade binders at four different temperatures. The results show that LAS parameters A and B at different temperatures maintain a linear relationship with the binder complex modulus (G*) measured at corresponding temperatures. Therefore, a fatigue life model, accounting for strain level and temperature, is proposed using a power function of the binder G*, which can account for temperature effects. To verify the model, its parameters are fitted using test data at two temperatures were used to predict the fatigue life at additional temperatures. This study findings offer a simpler and reliable method to predict the values of fatigue life at new temperatures using both 35% damage level and maximum stress failure criteria that are recommended in AASHTO TP101-12 and AASHTO TP101-14, respectively. The new prediction method will allow a wider use of the LAS procedure regarding the effects of temperature and strain level for which binders are subjected to the pavement. [ABSTRACT FROM AUTHOR]

Recently, there is a growing interest in increasing content of reclaimed asphalt pavement (RAP) material in the production of Hot Mix Asphalt (HMA) pavements to further reduce material costs and to preserve non-renewable resources. This study aims to evaluate the long-term performance of high RAP mixtures containing various softening oils. Both petroleum-based and bio-based oils were applied in preparing the 30% RAP and 50% RAP mixtures. The mixtures were subjected to the short-term oven aging (4 h), long-term oven aging (8 h), and extended-term aging (16 h) in the laboratory. Their performance, including the rutting, fatigue cracking at intermediate temperature, and low temperature cracking, were measured and compared with the control mixtures. The results indicate that the softening oils in this study can be used to produce asphalt mixtures containing high percentages of RAP with similar performance to a virgin mixture utilising the same aggregates and mixture design. In addition, the results show that making decisions to compare, qualify, or otherwise accept mixtures using the short-term aging results alone can be very risky. It is clearly shown in this study that relative ranking of mixture performance can change based on the level of aging. [ABSTRACT FROM AUTHOR]

Most of the techniques used today to evaluate practically moisture damage in asphalt pavements are involved in compacted asphalt mixtures. These tests generally simulate field conditions, and provide a performance-related parameter of moisture effects by applying mechanical techniques. No test of the compacted mixtures, however, can isolate the fundamental and rheological properties of the asphalt-aggregate bond, which hinder proper understanding and quantification of the moisture damage phenomenon. To avoid these complications and improve the evaluation of asphalt-aggregate interfacial properties in moist situations, this study proposes a new experimental method. In this method, dynamic shear rheometer was used to measure asphalt-aggregate interfacial properties. A degree of moisture damage relating to the interfacial properties was then quantified using linear viscoelastic concepts to propose a meaningful parameter, called wet to dry yield shear stress ratio. Moreover, possible factors such as film thicknesses, conditioning times, and chemical effects were studied in terms of the W/D YSS ratio. DOI: 10.1061/(ASCE)0899-1561 (2010)22:3(267) CE Database subject headings: Asphalt pavements; Damage; Viscoelasticity; Rheology; Parameters; Moisture. Author keywords: Pavement; Asphalt; Moisture damage; Rheology; Viscoelasticity.

During the last two decades, several research efforts have focused on the thermal cracking behavior of asphalt binders. Recently, important low-temperature cracking models have been introduced to include the failure properties and thermovolumetric properties at low temperatures. The main objective of this study is to evaluate selected modified asphalt binders in terms of low-temperature failure and related thermovolumetric properties. The effect of modification on fracture failure properties and related thermovolumetric properties of asphalt binder was determined by laboratory testing. The low-temperature cracking temperatures using the collected laboratory testing data were predicted. The focus of this study is on how commonly used asphalt modifiers affect the failure and thermovolumetric properties for a wide temperature range, in particular at low temperatures. Efforts were also made in this study to put more emphasis on the consideration of strain criterion, the effect of cooling rate, and nonlinearity of the coefficient of thermal contraction of asphalt binders into the prediction of low temperature cracking. The results indicate that modification of asphalt binders can have significant effects on their properties and predicted thermal cracking temperatures. The findings also suggest that in order to have a better understanding of binder behavior, the use of both failure and thermovolumetric properties is necessary. DOI: 10.1061/(ASCE)0899-1561(2009)21:5(198) CE Database subject headings: Asphalts; Binders, materials; Cracking; Temperature effects; Failures.

Adding recycling oils (also called as 'recycling agents' or 'rejuvenators') into the asphalt mixtures with Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) is a widely adopted strategy for improving potential resistance to cracking of recycled asphalt pavements. This study investigates the rheolgoical properties of two Bio-Oils and two Re-refined Engine Oil Bottoms (REOB) by using Dynamic Shear Rheometer (DSR) and Rotational Viscometer (RV) tests at various testing conditions, as well as their chemical properties by using the Fourier Transform-Infrared Spectroscopy (FTIR) measurement. The results are compared for the recycling oils after the Rolling Thin-Film Oven (RTFO), 20- and 40-hours Pressure Aging Vessel (PAV) aging. Furthermore, these four recycling oils were blended with a base binder at a high ratio (50%) and measured for their complex shear modulus and viscosity at various aging levels, as well as their infrared spectra. At the end, two recycling oils were selected to blend with a base binder at low ratios (2.9% and 5.7%) and measured for the standard Performance Grade (PG) properties and PG plus characteristics. The results of oil-asphalt low ratio blends indicate that recycling oil's content plays an important role in aging behaviour of the binders, not only the type of recycling oils. [ABSTRACT FROM AUTHOR]

A field and laboratory study was carried out to study the effect of pressure and temperature on the compaction of asphalt pavements. Density, temperature, number of passes, and type of roller were recorded in the field at four different paving projects in Wisconsin, with binder and mixture samples obtained from each project. Compaction in the field occurred at temperatures that ranged from 125 to 60[degrees]C. Densification was achieved only for temperatures above the 70-80[degrees]C range. Roller contact pressures were estimated between 300 and 700 kPa during the compaction process. Laboratory compaction was performed with Superpave gyratory compactor using the field compaction temperatures and contact pressures. The lab compaction results confirmed that below a certain temperature limit densification decreased significantly. Binder testing was performed to determine the binder viscosities in the full range of field compaction temperatures observed. The upper limit of viscosity for significant reduction in densification was estimated to be 50 Pa s. A procedure for identifying the lowest temperature at which acceptable densification rate can be achieved is proposed based on testing using the dynamic shear rheometer. The determination of the lower temperature limit for compaction is an important task that is absent in the current specifications. DOI: 10.1061/(ASCE)0899-1561(2008)20:6(440) CE Database subject headings: Asphalts: Concrete: Asphalt pavements: Highway construction: Soil compaction: Field tests: Laboratory tests.