Aged Asphalt Binders Research Articles

Aging of asphalt binder in hot pavement rehabilitation

Construction of new asphalt road pavements as well as traditional maintenance requires the use of a great amount of non-renewable resources, having important negative environmental and economic impacts. Thus, extending the service life and promoting the recycling or reuse of pavement materials represent two pillars of a sustainable development model. These strategies include also two approaches which involve heating and softening of the existing hot-mix asphalt (HMA) pavement, such as healing and hot-in place recycling. Modern and more efficient technologies potentially used for the on-site heating of flexible pavements are no longer based on electrical resistance systems but use microwaves or infrared radiant heaters, which can however lead to a further potential aging of asphalt binder and therefore negatively affecting the mechanical properties of recycled HMA.This article aims, through an experimental laboratory approach, to directly compare two heating methods potentially used in flexible pavement rehabilitation, i.e. infrared and microwave radiations, for a preliminary assessment of the heating process characteristics (temperature distribution, energy consumption and duration) and on asphalt binder aging phenomenon. The thermographic and rheological analyses revealed that microwave radiation represents a more energy-efficient solution compared to infrared, producing minor aging effects on asphalt binder.

Influences of aging conditions on the rheological properties of asphalt binders

ABSTRACTReliable assessment of asphalt binder aging is important for material selection and the prediction of asphalt property changes in field pavements. The apparent property changes of asphalt binder with aging, however, are affected by aging conditions. In this study, three aging treatment methods were applied to five types of asphalt binders, and the longest aging treatment period lasted for 1.5 years. Asphalt binder samples obtained during the aging treatment processes were systematically tested for dynamic rheological properties. The apparent aging susceptibility of asphalt binders was found to be affected by aging conditions. Thin-film aging under a more ‘natural’ condition appears to be quite effective in accelerating the aging process. The changes of the coefficients in the Christensen-Anderson model and the Williams–Landel–Ferry equation in the tests suggest that binders’ dynamic rheological properties during the long-term aging process may be reliably predicted through laboratory tests. This is conditioned on the binders having been artificially aged to pass the ‘spurt’ reaction stage and data points being collected from the ‘steady’ reaction stage under more ‘natural’ aging conditions. To predict asphalt binder aging in field pavements, additional research is needed to consider the influences of asphalt mixtures.

Investigation of rheological and chemical properties asphalt binder rejuvenated with waste vegetable oil

To improve the performance of asphalt mixture with high content of reclaimed asphalt pavement (RAP), rejuvenator is usually added. The traditional rejuvenator is non-renewable and contains large amount of carcinogenic polycyclic aromatic hydrocarbons. In this study, the effects of waste vegetable oil (W-oil) on rejuvenating aged asphalt binder were investigated in terms of rheological and chemical properties. The viscosity, complex shear modulus, and fatigue life were measured using Rotational Viscometer (RV) and Dynamic Shear Rheometer (DSR). The chemical properties were characterized by Gel Permeation Chromatography (GPC) and Fourier Transform Infrared Spectroscopy (FTIR). The experimental results indicated that the workability and fatigue resistance of aged asphalt were improved by addition of W-oil. The logarithm values of viscosity of rejuvenated asphalt at specific temperature showed linear relationship with the dosage of W-oil. The fatigue life of rejuvenated asphalt increased exponentially as the dosage of W-oil increased. There was no chemical reaction found between W-oil and aged asphalt. With the increasing content of W-oil, sulfoxide index (ISO) and the large molecule size (LMS) content decreased due to physical dilution. Besides, the workability and fatigue resistance of rejuvenated asphalt were found having close correlations with sulfoxide index and the LMS content.

Evaluation of rheological performance and moisture susceptibility of polyphosphoric acid modified asphalt binders

The effects of modification of asphalt binders with polyphosphoric acid (PPA) were evaluated in this study. Mechanistic performance was evaluated by examining the stiffness, rutting, and fatigue properties of two selected binders modified with different dosages of PPA. A surface science approach, namely the surface free energy (SFE) technique as employed to evaluate moisture susceptibility of different PPA-modified asphalt binder and aggregate systems. Since PPA is a hydrophilic material, two different crude oil originated PPA modified binders with selected liquid antistripping agents (LAAs) were evaluated. Binders modified with PPA and Styrene–Butadiene-Styrene (SBS) were also included in the test plan to observe their performance with a simultaneous presence of acid and polymer. Laboratory test results reveal that SBS-modified binders are more rutting resistant than the corresponding PPA-modified binders. The effects of LAA are contingent upon the crude origin of the asphalt binder. Furthermore, PPA did not show any negative effects on fatigue behaviour of long-term aged asphalt binders. From the SFE analysis it was concurred that PPA-modified binders could be more susceptible to moisture damage than the corresponding SBS-modified binders. Higher amount of PPA made asphalt binders more susceptible to moisture damage than lower amounts. Furthermore, Fourier Transform Infrared Spectroscopy (FTIR) spectra revealed no changes in the functional groups due to the addition of PPA. The outcome of this study is expected to help Arkansas Department of Transportation (ArDOT) and other agencies in revising their quality control guidelines for possible inclusion of PPA as an approved modifier for asphalt binders.

Quick heating method of asphalt pavement in hot in-place recycling

To improve the heating rate of asphalt pavement in Hot In-Place Recycling (HIR), a quick heating method was proposed. Considering input heat flux, the thermal capacity and thermal resistance of asphalt pavement materials, a novel heat transfer model was established based on energy conservation law. Time-dependent heating temperature field distributions of various heating methods were calculated with Euler formulation, and numerical simulation results from the heating transfer model were validated by measured results. The results indicate that one-way continuous heating method (OCHM) leads to an obvious temperature gradient along the depth direction at the upper layer of asphalt pavement, and the heating speed is too slow when the temperature at the bottom of the upper layer reaches 100 °C. However, the heating speed is increased using another reciprocating intermittent heating method (RIHM). The surface temperature is changed periodicity, and the operation is too complex to control all the peak temperatures at 180 °C, which leads to the aging or charring of asphalt binder. Finally, a new constant temperature heating method (CTHM) was proposed and the ideal heat flux curve was obtained. With CTHM, the surface temperature of asphalt pavement is always kept 180 °C to ensure the heating quality by adjusting the input heat flux. Especially, the heating speed with CTHM is the fastest compared with OCHM and RIHM.

State of the art review on mix design and mechanical properties of warm mix asphalt

Warm mix asphalt (WMA) is a high-speed emerging technology of producing asphalt mixture at lower temperature with equivalent performance of hot mix asphalt (HMA). It offers benefits such as energy savings, compaction aid for stiffer mixes, reduces emission, and reduces asphalt binder aging during production. This paper is an overview of mix design concept, mix design properties and mechanical properties (moisture-induced damage, rutting resistance and fatigue life) of WMA and same was compared with the properties of control HMA mixtures. Review indicates that mix design concept of WMA is similar to that of control HMA and possesses better mix design properties. Regarding mechanical properties, WMA mixtures were found more prone to moisture-induced damage, rutting and fatigue than control HMA mixtures due to lower production temperature but similar or better resistance were noticed with the use of modified and higher grade binders, addition of anti-stripping agents (ASA) and hydrated lime (HL), use of open graded mix and inclusion of recycled asphalt pavement (RAP). Further, the effect of nominal maximum aggregate size (NMAS) and design gyration (Ndesign) on mix design, NMAS and aggregate type and its water absorption on moisture-induced damage, NMAS, wheel load, test temperature, air voids, and binder grade on rutting, and NMAS, air voids, and stress or strain levels on fatigue properties of asphalt mixtures were analysed. Results indicated that NMAS had the significant effect on moisture-induced damage, rutting resistance and fatigue life of WMA mixtures. WMA mixtures made with aggregates of higher water absorption values were more prone to moisture-induced damage and even fail to meet minimum (tensile strength ratio) TSR requirements. Results also indicated that WMA mixtures made with modified and higher grade binder grade were high rut resistant. WMA mixtures tested at high stress or strain levels shows higher fatigue damage compared to WMA mixtures tested at lower stress or strain levels.

Investigation of functional group distribution of asphalt using liquid chromatography transform and prediction of molecular model

The present study investigated functional group distribution of virgin and aged asphalt binder through liquid chromatography (LC) transform, a device that combines the functions of Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The corresponding molecular models of virgin and PAV aged asphalt components were constructed. The temperature-dependent density of the model was calculated to verify the accuracy of the model. The chemical structure of the components was evaluated using a series of indicators, including the aromatic index, the aging index, the CO index and the δ (CH3)/δ (CH3 + CH2). The structural changes of components with molecular weight of the virgin and aged asphalt were also analyzed. The molecular simulation results indicated that the molecular model developed in this study was consistent with real asphalt.

Investigation of the flow and self-healing properties of UV aged asphalt binders

In this paper, the flow behaviors and self-healing properties of two asphalt binders with different ageing degrees were investigated. Fourier transform infrared spectroscopy (FTIR) test was first used to characterize the ageing degrees of the binders. Then, frequency sweep test was conducted to calculate the flow behavior indices of asphalt binders with different ageing degrees to determine their self-healing threshold temperatures and fatigue life recovery test was performed to investigate their real self-healing rates. The capillary flow test was finally carried out to simulate the flow ability of asphalt binders with different ageing degrees within cracks in asphalt. It was found in FTIR that the carbonyl index increased with the ageing degree of the binders and tended to level off once the binders approached their ageing limits. With the deepening of ageing, the self-healing threshold temperature and the flow activation energy of asphalt binders increased and their healing performance was getting worse. Once the asphalt binders were aged to a certain extent, no self-healing threshold temperature can be found and the fatigue-healing rate was very low. A strong correlation between self-healing threshold temperature, flow activation energy and self-healing ratio can be found.

Damage characteristics of waste engine oil bottom rejuvenated asphalt binder in the non-linear range and its microstructure

This paper aims to compare the damage characteristics of the waste engine oil bottom (WEOB) rejuvenated asphalt binder with aromatic extract oil rejuvenated asphalt binder in the non-linear range. To fulfil this objective, the aged asphalt binder was prepared by aging SBS modified asphalt binder in the laboratory. High temperature, fatigue and low-temperature damage characteristics in the non-linear range were evaluated by conducting multiple stress creep and recovery (MSCR) test, linear amplitude sweep (LAS) test and double edge notched tension (DENT) test, respectively. The microstructure of rejuvenated asphalt binders was characterized by environmental scanning electron microscope (ESEM). The results showed that although the performance of aged asphalt binder can be restored to some extent with two recycling agents, however after conditioning in the bath for 120 h, the two rejuvenated asphalt binders exhibited different ductile states. The microstructure of rejuvenated asphalt binders revealed that WEOB rejuvenated asphalt binder presented a more gelation transition than aromatic extract oil rejuvenated asphalt binder which could be considered as the main reason for the reduction in the ductile performance of WEOB rejuvenated asphalt binder.

Identification of asphalt aging characterization by spectrophotometry technique

During the construction and service life of asphalt pavement, the bituminous material is inevitably exposed to sunlight, oxygen, water, ambient temperature and other climate conditions, which lead to aging or oxidation of asphalt binder and thus accelerate the deterioration of asphalt pavement. In order to characterize the aging impact of asphalt materials, conventional methods have been used including rheological test, Fourier transform infrared spectroscopy (FTIR), Gel Permeation Chromatography (GPC), etc. However, some drawbacks limited their application in practice such as the complexity of test procedures and the expensive test instruments. A novel method, spectrophotometry, was introduced in this study to analyze the aging characteristics of asphalt binder. The sample preparation method and test procedures were developed and the correlation analysis was used to assess the feasibility of this method. The experiments illustrated that a 2 g/L “toluene-heptane” asphalt suspension (0.2 g/mL in toluene, 2 g/L in heptane) and a test of absorbance area from 700 nm to 900 nm could be effectively used to characterize the aging of asphalt. Furthermore, the test and statistical results also demonstrated that the absorbance change of asphalt during the aging procedure was from the increased asphaltene. Moreover, the FTIR test indicated that the feasibility of using spectrophotometry to characterize the aging of asphalt. In addition, the research indicated that the sources and penetration grades could not be used as mutual indices to characterize the aging resistance of asphalt.

Investigation of sodium stearate organically modified LDHs effect on the anti aging properties of asphalt binder

The layered double hydroxides (LDHs) has been widely used as the anti-aging modifier to improve the anti aging performance of an asphalt binder, but for the different chemical and physical properties of LDHs with asphalt binder, the compatibility of them is not very well, therefore the best modification effect can not be obtained. The sodium stearate was designated to organically modify the LDHs to enhance its improvement effect on the anti aging performance of asphalt binder. The modern test instruments such as Fourier transform infrared spectroscopy, X-ray diffractometer, scanning electron microscopy, ultraviolet visible spectrophotometer were used to investigate the sodium stearate effect on the characteristics of LDHs. In addition, the LDHs modified styrene–butadienestyrene modified asphalt (LDHs/SBS MA) and sodium stearate organically modified LDHs (SS-LDHs) modified styrene–butadienestyrene modified asphalt (SS-LDHs/SBS MA) were prepared by the melt blending method, the thin film oven test and UV aging test were conducted to simulate the short term thermo-oxidative aging and UV aging of asphalt binder respectively. Finally, the chemical structure, viscosity, and complex modulus of LDHs/SBS MA and SS-LDHs/SBS MA before and after aging were tested respectively. The results show that the sodium stearate can improve the compatibility of LDHs with styrene–butadienestyrene modified asphalt binder (SBS MA). Both LDHs and SS-LDHs can improve the anti thermo-oxidative aging and anti UV aging performance of SBS MA. Notably, the improvement effect of SS-LDHs on the anti aging performance of SBS MA is much better than that of LDHs.

Evolution of molecular packing and rheology in asphalt binder during rejuvenation

Effective rejuvenators that restore the thermo-mechanical properties of aged asphalt would extend pavement service life and increase utilization of recycled material, cutting material and environmental costs. However, the efficacy and mechanism of action need to be characterized in order to optimize rejuvenator formulation and dosage. This study introduces the RIPS method (Rejuvenation Index based on Polydispersity and Stiffness) which applies rheological characterization to build a simple model for examining and predicting the effect of rejuvenation on the rheology, polydispersity, and microstructure of aged asphalt binder. RIPS showed that addition of a specific bio-rejuvenator significantly improved the low-temperature properties of highly aged binder. The method accurately predicted the binder relaxation modulus and could calculate the exact rejuvenator dosage needed to restore the performance grade to specification. The rejuvenation mechanism was further examined using DSC, FTIR, and quantum level computational modeling, which found that polar chemical groups in the bio-rejuvenator could be responsible for solubilizing similar polar groups in aged binder leading to reduced molecular aggregate size and restoration of the thermo-mechanical properties of aged binder. These results provide insight into the molecular mechanisms of rejuvenation and offer a path towards more rational design and deployment of rejuvenator formulations.

Effects of aging on rheological properties of asphalt materials and asphalt-filler interaction ability

The rheological properties of asphalt mastics and asphalt-filler interaction play key roles on the performances of asphalt mixtures. However, the rheological properties of asphalt mastics and asphalt-filler interaction are significantly influenced by aging which exists in the compaction stage of asphalt mixtures. In order to analyze the effects of aging on rheological properties of asphalt binders, asphalt mastics and asphalt-filler interaction, the Dynamic Shear Rheometer (DSR) tests and Bending Beam Rheometer (BBR) tests were conducted for unaged and aged specimens. Results indicate that the aging can enhance the cohesion properties of asphalt binders and mastics, and so the rutting resistance of asphalt binders and mastics is better with an increase in aging degree. However, the low temperature properties of asphalt binders and mastics are worse with an increase in aging degree. The two indices K-B-G∗ and K-B-δ were selected to evaluate asphalt-filler interaction ability. Results show that these two indices have the consistency to evaluate asphalt-filler interaction ability. And also the two indices can reflect the difference of interaction ability of different aged asphalt binders and fillers. The deeper aging degree of asphalt binders is, the worse asphalt-filler interaction ability is. Within the same aging degree, the interaction ability of asphalt 70# with higher asphaltene and resins contents is stronger than asphalt 90#. Therefore, the aging affects the asphalt-filler interaction ability via changes of asphalt active components.

Evaluation of aging behaviors of asphalt binders through different rheological indices

The performance of asphalt pavement is seriously affected by aging of asphalt binder, so indices are expected which can not only evaluate aging resistance of asphalt binder but also indicate asphalt mixture performance. The objective of this paper was just to investigate effects of different rheological indices which present tighter and clearer correlation with asphalt mixture performance in evaluating asphalt binder aging behaviors, these indices including complex modulus (G∗) and phase angle (δ) master curves, rutting factor (G∗/sinδ), zero shear viscosity (ZSV), non-recoverable compliance (Jnr), fatigue factor (G∗·sinδ) and DSR function (DSRFn). Thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) irradiation were applied to simulate short-term, long-term thermal oxidation and photo oxidation aging, respectively. Frequency sweep tests and multiple stress creep recovery (MSCR) tests were conducted on three asphalt binders (60/80 pen grade base asphalt, styrene–butadiene-styrenecopolymer (SBS) modified asphalt and styrene butadiene rubber (SBR) modified asphalt) at different aging conditions. Meanwhile, aging sensitivities shown by different rheological indices were compared. The relationships between rheological indices were also discussed. The results showed that the ranking of aging resistances among asphalt binders evaluated by different rheological indices were nearly consistent and SBS modified asphalt exhibited the best aging resistance to three aging methods. Jnr and δ tended to decrease with the growth of aging severity, whereas other rheological indices were just contrary to this trend. Moreover, DSRFn proved to be the most sensitive index to aging. Based on correlation analyses, three groups of indices exhibited a strong correlation to each other, namely DSRFn versus G∗/sinδ, Jnr (0.1 kPa) versus Jnr (3.2 kPa) and Jnr (0.1 kPa) versus ZSV.

Investigating molecular conformation and packing of oxidized asphaltene molecules in presence of paraffin wax

This study investigates the effect of paraffinic wax (as a base component in many commercial rejuvenators) on the rheological and intermolecular properties of aged asphalt binder. Samples of oxidized asphalt binder doped with (1%, 3%, 5%, and 10%) paraffin wax were characterized using the rotational viscometer (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR) and direct tension test (DTT). The RV results showed an improvement trend in workability of aged binder as wax content increased. The DSR results (for a temperature range of 10–76 °C) showed lower complex modules for wax-doped specimen than control specimen. The BBR test results performed at sub-zero temperature showed that an increase of wax dosage led to higher creep stiffness modulus indicating that the asphalt binder became generally stiffer in presence of wax at low temperature. However, fracture energy measured through DTT test showed a significant reduction in presence of wax. The latter can be attributed to plausible weak secondary bonds between wax and asphaltene molecules as well as crystallization of wax molecules at low temperature within the asphalt matrix. This in turn can lead to wax crystals playing as stress localization point giving rise to crack nucleation at the wax-asphalt interface reducing overall fracture energy; it was further observed that as the wax content increased, the asphalt binder became more brittle.To further investigate the effect of wax on the molecular conformation and packing in aged asphalt binder, a molecular simulation was performed on a system of wax and oxidized asphaltene. The results of molecular simulations showed a reduction in formation of oxidized asphaltene nano-aggregates as the amount of wax increased in the wax-doped oxidized asphaltene matrix at room temperature, which was also confirmed by size exclusion chromatography. Furthermore, the radial distribution function results showed a less packed structure of oxidized asphaltene molecules in presence of wax molecules. Increasing the wax content also increased the diffusion coefficient of wax into the oxidized asphaltene matrix within a solvent medium. It was also showed that interaction energy of a dimer of oxidized asphaltene is at a lower energy state in presence of wax molecules, which suggests that wax molecules can promote dimerization of oxidized asphaltene molecules while suppressing nano-aggregates formation.

Research on the aging and rejuvenation mechanisms of asphalt using atomic force microscopy

To investigate the mechanism of aging and rejuvenation of asphalt, traditional laboratory and atomic force microscopy (AFM) tests were conducted for asphalt specimens, respectively. Experimental results indicated that the penetration and ductility of virgin asphalt significantly decreased after aging. These results could not satisfy the technical requirements of the specification. The softening point and viscosity of virgin asphalt increased due to aging process. Rejuvenator had a significant impact on the performance of aged asphalt binders. The penetration of aged asphalt binders conspicuously increased with an increase in the rejuvenator content. The softening point and viscosity of aged asphalt binders obviously decreased with the rejuvenator content increasing, and the optimum rejuvenator content was about 12% by mass in this study. Through comparing virgin and aged asphalt binders via AFM test, it confirmed that light components contents of asphalt binders greatly decreased during the aging process. The aging effect of asphalt binder was a sluggish process, and the content and microstructure of its internal components would vary with the altering of aging degree. The rejuvenator did not recompose the composition of aged asphalt binders. The results showed that the rejuvenation process of rejuvenator was a physical interaction, and the kinds and contents of rejuvenator would not alter the microstructure of recycled asphalt binders.

Effect of curing conditions on properties of cement asphalt emulsion mixture

The properties of cement asphalt emulsion mixture (CAEM) are influenced by curing conditions. In this paper, the strength properties of CAEM are investigated at different curing humidities and periods. Then, the moisture susceptibility test and rutting resistance test are performed to evaluate the effect of typical curing procedures on the emulsion-based mixtures. In order to understand the diversity of different curing procedures, the chemical composition and microstructure of cement asphalt mastic (CAM) are analyzed by Fourier transform infrared (FTIR) spectrometer, X-ray diffraction (XRD) analyzer, and environmental scanning electron microscope (ESEM). The results indicate that the effect of curing humidity on strength development depends on the cement content and curing period. It is recommended to cure all mixtures with lower humidity. The higher temperature accelerated curing for several days can stimulate a normal temperature curing for several months. The equivalent relationships between accelerated curing and normal temperature curing are developed based on the strength and performance analysis. By comparing FTIR results at different curing regimes, it can be found that no obvious asphalt binder aging appears in CAM with the typical accelerated curing procedure. XRD analysis founds that the accelerated curing improves the content of some hydration products content, while leads to the more cement particles encapsulated by asphalt film. Considering results of FTIR and XRD, it is testified that the microstructure characteristics of hydration products in CAM with two curing regimes are obviously different, which can explain the performance variations of CAEM with these curing procedures.

Displacement Investigation of KNN‐Bitumen‐Based Piezoceramics in Asphalt Concrete

Piezoelectric material has excellent characteristics of electromechanical coupling so that it could be widely applied in structural health monitoring field. Nondestructive testing of piezoelectric technique becomes a research focus on piezoelectric field. Asphalt concrete produces cumulative damage under the multiple repeated vehicle load and natural situation, so it is suited material and structure for nondestructive application. In this study, a test system was established by driving power of piezoceramic, laser displacement sensor, computer, and piezo‐embedded asphalt concrete. Displacement, hysteresis, creeps, and dynamic behavior of KNN piezoceramic element embedded in asphalt concrete were tested. The results indicate that displacement output attained 0.4 μm to 0.7 μm when the loads were from 0 N to 150 N. The hysteresis was not obvious when the load was from 0 N to 100 N, aside from higher loads. The creep phenomenon can be divided into two parts: uptrend and balance. The more serious the asphalt binder ageing is, the larger the displacement is, when piezo‐asphalt concrete has already been in serious ageing.

Retarding aging of asphalt binders using antioxidant additives and copolymers

The rheological properties of asphalt binders change with aging. Aging is accelerated at elevated temperatures due to binder oxidation, leading to fatigue cracking and eventually pavement failure under heavy and repeated traffic loading. This study examined the effect of various antioxidant additives and copolymers with antioxidant agents on retarding the aging of asphalt binders. The performance of antioxidants was evaluated at the binder and mastic levels. Two unmodified binders were tested and fine asphalt mixtures made with these binders and three different aggregates were prepared and evaluated. Fatigue characteristics of asphalt binders and fine portion of asphalt mixtures (FAM) were determined before and after aging and an aging index was defined to evaluate the effect of antioxidants and copolymers on aging. The results showed that certain antioxidants and copolymers such as Redicote AP, Solprene and Calprene may retard the aging and improve the rheological properties of the asphalt binders. In addition, the results of FAM testing confirmed the favourable effect of certain antioxidants on improving the resistance to fatigue. In addition, the type of aggregate was found to influence the rate of aging of asphalt mixtures.

Determination of oxygen diffusion coefficients of compacted asphalt mixtures

The oxidative aging of asphalt binder in asphalt mixture is a key factor that affects the long-term durability of asphalt pavement. The aging susceptibility of an asphalt mixture is dependent on oxygen transport and consumption in the mixture. In this study, an apparatus was developed to measure oxygen diffusion and consumption in compacted asphalt mixtures, and methods to compute oxygen diffusion and possible consumption of asphalt mixtures were evaluated and compared. Oxygen diffusion coefficients of samples prepared with different asphalt mixture designs and air void contents were determined, and correlations between the diffusion coefficients and samples’ volumetric characteristics were examined. The oxygen environment exposed by asphalt binders in pavements and its implication on pavement durability were also discussed based on simulated oxygen concentration profiles with time. The developed apparatus and test procedure were found to be suitable to measure the oxygen diffusion coefficients of compacted asphalt mixtures. It was also found that oxygen consumption during the diffusion test at room temperature is negligible, and both numerical and analytical methods perform equally well in calculating oxygen diffusion coefficients. The oxygen diffusion coefficients of the tested asphalt samples vary in orders of magnitude, dependent not only on air void contents but also on other volumetric characteristics. The traditional models to predict the oxygen diffusion coefficients of dry porous media are not fit for compacted asphalt mixtures. The oxygen diffusion coefficients of asphalt mixtures have significant implications on oxygen level exposed by asphalt binders inside of the pavements; therefore, they may be used as an indicator in asphalt mixture design and construction quality control.