Short- and Longer-Term Effects of Short-Term Aging on Asphalt Mixture Properties

Smith, Braden T.; Howard, Isaac L.

doi:10.1061/(asce)mt.1943-5533.0002170

Cited by 12 publications

(8 citation statements)

References 11 publications

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“…Smith and Howard reported Cantabro testing simulated 4-5 years of field aging of mixes M14 to M16 (39), which is consistent with the values from mixes M17 to M20. Several findings from mixes M14 to M16 have already been published (38,39,44) and the trends in those publications agree that Cantabro testing and the combinedeffects laboratory conditioning protocol are promising.…”

Section: Normalized Mechanical Property Trendsmentioning

confidence: 72%

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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Section: Normalized Mechanical Property Trendsmentioning

confidence: 72%

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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“…As such, the conclusions drawn for this test section are not necessarily applicable to all climate regions, but it would be well suited to couple with data from other climate regions. Second, many factors relative to the construction approach for this test section were considered in Smith and Howard ( 29 ) in which the same test section was considered from a mixture perspective. Findings in Smith and Howard ( 29 ) suggested that haul time effects between the strips considered in this paper were secondary effects.…”

Section: Analysis Of Resultsmentioning

confidence: 99%

“…Second, many factors relative to the construction approach for this test section were considered in Smith and Howard ( 29 ) in which the same test section was considered from a mixture perspective. Findings in Smith and Howard ( 29 ) suggested that haul time effects between the strips considered in this paper were secondary effects. Thus, construction effects were considered on a mix basis and haul time effects were not considered directly.…”

Section: Analysis Of Resultsmentioning

confidence: 99%

“…Surface materials had an R 2 of 0.06 and p -value of 0.63, and non-surface materials had an R 2 of 0.00 with a p -value of 0.92. Although air void effects were likely for this dataset, interaction of the factors described in Smith and Howard ( 29 ) prevented the authors from considering air voids directly.…”

Section: Discussionmentioning

confidence: 99%

“…PAV rates also varied when comparing rates from test strip to test strip. However, there were multiple variables that could have affected the rates between test strips (e.g., air voids, mixing temperature, and haul time) ( 29 ). Regression analysis between Table 7 PAV rates and average air void levels from Table 1 indicated that there was no significant relationship between air voids and the amount of PAVi necessary to simulate field aging for the test section considered.…”

Section: Discussionmentioning

confidence: 99%

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Comparing Pressure Aging Vessel Time to Field Aging of Binder as a Function of Pavement Depth and Time

Smith¹,

Howard

Jordan³

et al. 2018

Transportation Research Record: Journal of the Transportation R

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The AASHTO R28 pressure aging vessel (PAV) binder conditioning protocol has been heavily used for over two decades as part of purchasing specifications. Many paving industry changes have occurred since PAV was implemented in the early 1990s. This paper provides discussion with respect to a controlled test section in which the exact binders from construction were subjected to multiple PAV times and compared with properties observed after 2 or 4 years of field aging. The data suggests that 2 and 4 years of field aging were best simulated by 21 h and 45 h of PAV time for binders extracted from the top 1.3 cm of the pavement surface. For binders extracted from 5.0 to 6.3 cm below the pavement surface (i.e., at depth), 2 and 4 years of field aging were best simulated by 3 and 14 h of PAV conditioning, respectively. These results indicate that a PAV rate of 11 h per year of simulation seemed adequate for binders aged on the pavement surface, and a PAV rate of 3 h per year of simulation seemed most reasonable for binders aged at depth. Considering these rates, the current 20-h protocol in R28 seems to simulate roughly 2 years of aging at the pavement surface and about 6.5 years at depth. The amount of field aging simulation at depth is within the range of 5 to 10 years of aging suggested by R28.

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