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

Elwardany, Michael D.; Rad, Farhad Yousefi; Castorena, Cassie; Kim, Y. Richard

doi:10.12783/aapt2018/33815

Cited by 10 publications

(25 citation statements)

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“…In addition, binders were extracted and recovered at various depths from a select group of field cores obtained from in-service pavements. The AIPs of the field-aged binders were measured and compared with laboratory-aged oxidation rates to determine the laboratory aging durations that matched the target field AIPs for specific projects (11,12). The AIP measurements that were taken from binders extracted and recovered from laboratory-aged loose mixtures were also used to develop and verify the rigorous rheology-based oxidation kinetics model given in Equations 1 through 3 (11,12).…”

Section: Background Of Development Of Original Caimentioning

confidence: 99%

“…The AIPs of the field-aged binders were measured and compared with laboratory-aged oxidation rates to determine the laboratory aging durations that matched the target field AIPs for specific projects (11,12). The AIP measurements that were taken from binders extracted and recovered from laboratory-aged loose mixtures were also used to develop and verify the rigorous rheology-based oxidation kinetics model given in Equations 1 through 3 (11,12). This kinetics model was adapted from the model proposed by Glaser et al by using the logarithm of the dynamic shear modulus, log G*, at 64°C and 10 rad/s as an AIP rather than carbonyl plus sulfoxide absorbance peaks (16).…”

Section: Background Of Development Of Original Caimentioning

confidence: 99%

“…Moreover, Elwardany et al verified that long-term aged loose mixtures can be compacted at the specified compaction temperature ( 7 ). The original NCHRP 09-54 project developed a set of laboratory aging conditions to represent the long-term aged state of asphalt mixtures in a pavement as a function of climate and depth using loose mixture oven aged at 95°C ( 11 , 12 ). The aging temperature of 95°C was selected based on a comparison between the properties of loose mixtures aged at 95°C and 135°C.…”

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confidence: 99%

“…These chemical changes can affect cracking performance, and thus long-term aging at 135°C for performance testing should be avoided to best reflect field aging ( 13 ). The duration of laboratory aging that is specified in the NCHRP 09-54 procedure varies as a function of hourly pavement temperature history and depth and is based on a kinetics-derived and field-calibrated climatic aging index (CAI) ( 11 ). In other words, CAI is a regression equation that is derived from the rigorous kinetics model.…”

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confidence: 99%

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

Braswell¹,

Saleh

Elwardany

et al. 2020

Transportation Research Record: Journal of the Transportation R

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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 found with regard to the laboratory aging durations for WMA materials compared with HMA materials, but there were differences between the RAP and non-RAP mixtures. In some instances, the short-term aged RAP mixtures that were prepared according to AASHTO R 30 exceeded the aging level of 4-year-old field cores, suggesting that refinement of this standard short-term aging procedure may be necessary. Approximately half of the PMA sections evaluated exhibited outlier behavior that could have been caused by the unrealistically harsh thermal history of the field projects from which the cores were acquired.

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Section: Background Of Development Of Original Caimentioning

confidence: 99%

Section: Background Of Development Of Original Caimentioning

confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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

Braswell¹,

Saleh

Elwardany

et al. 2020

Transportation Research Record: Journal of the Transportation R

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“…The recent NCHRP 09-54 project established an alternative pavement aging model based on rigorous oxidation kinetics modeling that can be used to predict the change in |G*| as a result of aging at 64°C and 10 rad/s as a function of hourly pavement temperature history data and depth below the pavement surface (7,(15)(16)(17). This model is shown in Equations 1, 2, and 3. log G* field predicted = log G* o, field j j The NCHRP 09-54 pavement aging model requires hourly pavement temperature data from the Enhanced Integrated Climate Model (EICM), the materialdependent parameter M, and log |G*| at the STA condition as inputs.…”

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Predictive Framework for Modeling Changes in Asphalt Mixture Moduli with Oxidative Aging

Saleh

Mocelin

Rad

et al. 2020

Transportation Research Record: Journal of the Transportation R

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This paper presents a predictive framework for asphalt mixture moduli as a function of aging time with two levels of sophistication. This work is built on the method currently implemented in Pavement mechanistic-empirical (ME) that uses an effective time/frequency concept based on time-aging superposition to model the effect of aging on a mixture’s modulus. Time-aging superposition implies that an asphalt mixture’s modulus mastercurves, corresponding to different aging levels, coincide when they are shifted horizontally on the log-frequency axis. This study improves the accuracy of the existing model by decoupling the time-temperature and time-aging shifts. The new framework also uses the binder dynamic shear modulus | G*| as an aging index instead of the viscosity, which is used in Pavement ME. The | G*| aging index is used to calculate an effective frequency at short-term aging (STA), which is then used in the asphalt mixture sigmoidal model to calculate the corresponding asphalt mixture modulus with aging. The pavement aging model introduced by NCHRP 09-54 predicts log | G*| at 64°C and 10 rad/s for a specific field-aged condition and pavement depth. The proposed framework can use the predicted log | G*| to predict the mixture’s corresponding dynamic modulus (| E*|) at that aging level and pavement depth. Level 1 of this framework requires characterizing the | G*| at STA and calibrating the NCHRP 09-54 pavement aging model as well as measuring the mixture | E*| at STA. Level 2 does not require any binder testing, providing relatively less accurate predictions but relieving some testing requirements.

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Combined Effects of Oxidation, Moisture, and Freeze–Thaw on Asphalt Mixtures

Bazuhair

Howard

Middleton³

et al. 2020

Transportation Research Record: Journal of the Transportation R

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This article demonstrates the need to laboratory condition asphalt mixtures to simulate combined environmental effects and then to test unconditioned and conditioned specimens in a manner that damage from these environmental effects can be accumulated. The current state-of-the-art for evaluating asphalt mixtures for use on projects relies on either single-mechanism laboratory conditioning such as oxidation in AASHTO R30, or test methods that cannot accumulate combined effects such as indirect tensile strength in AASHTO T283. This article evaluated hundreds of laboratory-conditioned and field-aged specimens in a hot and no-freeze climate to demonstrate a laboratory conditioning protocol that was able to simulate at least 4 years of field aging, whereas conventional single-mechanism protocols were not. Temperature and moisture conditions within asphalt mixtures were measured over time and used as part of the assessment. The conditioning protocol that showed the most promise consisted of combined exposure to oxidation, moisture, and freeze–thaw mechanisms. The specific combined-effects conditioning protocol used here was 5 days of oxidation at 85°C, 14 days of moisture while submerged in 64°C water, and one freeze–thaw cycle. Other combined-effects protocols could be more suitable for other environments or situations; the main point of this article is that inclusion of oxidation, moisture, and freeze–thaw conditioning into one protocol is promising. The environmental conditions and mechanical property test data presented here suggest the asphalt industry needs to be harsher on mixes during laboratory evaluations, and that combined environmental effects conditioning should be given implementation consideration.

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

Cited by 10 publications

References 2 publications

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

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

Predictive Framework for Modeling Changes in Asphalt Mixture Moduli with Oxidative Aging

Combined Effects of Oxidation, Moisture, and Freeze–Thaw on Asphalt Mixtures

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