Determination of percent working binder in recycled asphalt pavement materials

Al‐Qadi, Imad L.; Carpenter, S H; Roberts, G.; Özer, Hasan

doi:10.1201/9780203881200.ch47

Cited by 41 publications

(66 citation statements)

References 1 publication

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“…Most of road state agencies and country regulations assume a full blending between the aged and virgin binders [ 2 , 16 , 27 ]. Conversely to this widespread practice, according to several studies, only a portion of the RAP binder is available and can act as a binder in the new formulation [ 28 , 29 ]. The definition of the degree of blending and the diffusion that will occur between the virgin and aged binders represents one of the main obstacles to the design asphalt mixtures with high and very high contents of RAP, as there are no overall well-defined procedures for their determination [ 19 , 28 ].…”

Section: Limits To the Increase Of Rap Content In Hma Mixturesmentioning

confidence: 99%

“…The definition of the degree of blending and the diffusion that will occur between the virgin and aged binders represents one of the main obstacles to the design asphalt mixtures with high and very high contents of RAP, as there are no overall well-defined procedures for their determination [ 19 , 28 ]. Furthermore, increasing the RAP content may require the addition of softening agents and/or rejuvenators to restore the properties of the aged binder [ 29 ]. The introduction of any recycling agent represents an additional variable in the mix design, requiring the selection of a compatible agent and its dosage.…”

Section: Limits To the Increase Of Rap Content In Hma Mixturesmentioning

confidence: 99%

“…From a mechanical point-of-view, the increase of RAP content in new formulations implies a potential increase in the stiffness of the final asphalt mixes [ 16 , 25 ], which is mainly dependent on the stiffness of the RAP binder [ 29 ]. A stiffer asphalt concrete might be less resistant against cracking due to fatigue, thermal shock and cracking reflection, representing the main reason for the reluctance of road agencies to the use of RAP mixtures [ 25 ].…”

Section: Limits To the Increase Of Rap Content In Hma Mixturesmentioning

confidence: 99%

“…How much blending occurs between the RAP binder and added virgin binder is still debated [ 21 , 28 ]. A correct evaluation is fundamental since the assumption of full blending, i.e., the full activation of aged binder, will result in underestimated binder content of the resulting mixture if the RAP aggregates are partially behaving as a black rock [ 29 ], leading to cracking, ravelling and moisture damage of new formulations [ 19 ]. On the other hand, the assumption of black rock behaviour when RAP binder clearly contributes to the mixture performance will lead to a higher final binder content [ 29 ], which can cause plastic deformations of final asphalt concrete [ 19 ].…”

Section: MIX Design Of Mixtures With High and Very High-content Ofmentioning

confidence: 99%

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The Challenges of Using Reclaimed Asphalt Pavement for New Asphalt Mixtures: A Review

2020

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Reclaimed Asphalt Pavement (RAP) material mainly consists of removed asphalt concretes from existing infrastructures and, to a minor extent, of wasted or rejected mixes during the production processes. Being composed of two valuable non-renewable resources, i.e., aggregates and bituminous binder, its conscious use can ensure the sustainability of asphalt pavement construction. Thanks to the use of RAP material in new asphalt products, the USA saved 4.1 million tons of virgin binder and 78 million tons of virgin aggregates in 2018. Therefore, the use of RAP for the production of new asphalt formulations at the top of the recycling hierarchy is preferable instead of being down-cycled in low-value applications. The RAP material represents one of the most re-used construction products worldwide; in 2018, approximately 88% wt. and 72% wt. of RAP were used in USA and Europe, respectively, as aggregates for Hot, Warm and Cold Asphalt Mixtures and for unbound layers. Several studies have revealed positive responses of the recycled asphalt mixtures with high or very high content of RAP. However, the common practices of many countries still limit the RAP content to a 15–20% wt., on average, in the recycled asphalt mixes. The amount of RAP in asphalt concretes can be significantly increased by applying good management practices of the RAP, either processed or not, as well as novel production technologies and advanced mix design approaches. This manuscript aims to summarize the state-of-the-art of use of RAP aggregates in new asphalt mixtures. The economic and environmental benefits are also discussed.

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Section: Limits To the Increase Of Rap Content In Hma Mixturesmentioning

confidence: 99%

Section: Limits To the Increase Of Rap Content In Hma Mixturesmentioning

confidence: 99%

Section: Limits To the Increase Of Rap Content In Hma Mixturesmentioning

confidence: 99%

Section: MIX Design Of Mixtures With High and Very High-content Ofmentioning

confidence: 99%

See 2 more Smart Citations

The Challenges of Using Reclaimed Asphalt Pavement for New Asphalt Mixtures: A Review

2020

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“…The role of recycled asphalt pavement (RAP) is remarkable and being enhanced with time, as it not only fulfils the requirements but is also cost and environment efficient. There are various methods for asphalt recycling where binder and aggregate are main materials which are reused to build pavement [ 1 , 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

Investigation on Hamburg Wheel-Tracking Device Stripping Performance Properties of Recycled Hot-Mix Asphalt Mixtures

et al. 2020

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Moisture damage in hot mix asphalt pavements is a periodic but persistent problem nowadays, even though laboratory testing is performed to identify different moisture-susceptible mixtures. In this study, a Hamburg Wheel Tracking device (HWTD) was used for rutting tests which were conducted on control and a high percentage of recycled asphalt pavement (RAP), i.e., 30%, 50% and 100% of virgin mixtures, under air dry and water-immersed conditions. Similarly, the extracted bitumen from RAP was tested for binder physical properties. Results showed that the asphalt mixtures containing RAP have less rut depth as compared to the control mix both in air dry and immersion conditions and hence showed better anti-rutting properties and moisture stability. Stripping performance of control and RAP containing mixtures was also checked, concluding that the RAP mixture was greatly dependent on the interaction between the binder (virgin plus aged) and aggregates.

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Quantitative evaluation of asphalt blending characteristics in epoxy‐modified hot recycled asphalt mixtures based on 3D confocal fluorescence technology

Zhang,

Cheng,

et al. 2023

J of Applied Polymer Sci

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This study proposes a novel method to quantitatively evaluate the blending effect between aged asphalt and epoxy asphalt in epoxy asphalt‐modified hot recycled asphalt mixture, based on three‐dimensional confocal fluorescence microscopy technology. Samples of epoxy asphalt‐modified hot recycled asphalt mixtures were prepared in a laboratory using new aggregates, epoxy asphalt, and reclaimed asphalt pavement materials that were simulated in the laboratory by subjecting new asphalt mixtures to a short‐term and long‐term aging process. Cube‐shaped stone aggregates were designed to distinguish between new aggregates and reclaimed aggregates. The distribution of epoxy resin in the epoxy asphalt‐modified hot recycled mixtures was tracked using a laser scanning confocal microscope. To address the depth attenuation issue caused by light absorption and scattering, as well as the overall intensity differences resulting from field depth differences and attenuation morphology, a depth compensation function and a feature weight allocation method were proposed. Results from the above method indicated that the degree of blending (DoB) ranged from 65% to 75% on the surface of new aggregates but from 45% to 70% on the surface of reclaimed aggregates. Most of the old asphalt still adhered to the surface of reclaimed aggregates after migration. The proportion of epoxy asphalt in the outer layer of asphalt film on new aggregates is higher than that on reclaimed aggregates. The DoB between the asphalt binders significantly decreased as the aging degree increased. Increasing the epoxy content reduced the viscosity of the epoxy asphalt and effectively improved the DoB between the new and old asphalt binders.

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Determination of percent working binder in recycled asphalt pavement materials

Cited by 41 publications

References 1 publication

The Challenges of Using Reclaimed Asphalt Pavement for New Asphalt Mixtures: A Review

The Challenges of Using Reclaimed Asphalt Pavement for New Asphalt Mixtures: A Review

Investigation on Hamburg Wheel-Tracking Device Stripping Performance Properties of Recycled Hot-Mix Asphalt Mixtures

Quantitative evaluation of asphalt blending characteristics in epoxy‐modified hot recycled asphalt mixtures based on 3D confocal fluorescence technology

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