scholarly journals A Sustainability Perspective for Unbound Reclaimed Asphalt Pavement (RAP) as a Pavement Base Material

2018 ◽  
Vol 11 (1) ◽  
pp. 78 ◽  
Author(s):  
Christina Plati ◽  
Brad Cliatt
Keyword(s):  
Mechanical Behavior ◽  
Asphalt Pavement ◽  
Constitutive Models ◽  
Base Material ◽  
Pavement Design ◽  
Environmental Benefits ◽  
Systematic Evaluation ◽  
Reclaimed Asphalt Pavement ◽  
Reclaimed Asphalt ◽  
Pavement Base

The present study aims to investigate reclaimed asphalt pavement (RAP) materials for utilization for a pavement base layer material with the goal towards increasing the reutilization of materials and the movement towards increased pavement sustainability. Reduced cost for materials and transportation of materials, overall environmental benefits and many other advantages have led to increased interests in utilizing RAP in pavements including as base materials for highway/roadway construction projects. The potential advantages of utilizing RAP as an unbound base material are known; however, its overall application is still limited partially due to the lack of systematic evaluation studies for the parameterization of RAPs mechanical behavior in pavement design. With this in mind, the current investigation focuses on the resilient modulus (Mr) properties of RAP aggregates in terms of a material’s elastic response. Experimental data from tri-axial stress tests on specimens consisting of RAP, aggregates and a mixture of both materials are investigated. A number of constitutive models for the description of mechanical behavior of RAP materials are investigated. The required procedures for determining the constitutive constants of the constitutive models is outlined for the aforementioned materials. A comparative analysis is applied, and the related results are evaluated. The main conclusion is that RAP materials can be utilized as a base material in the framework of pavement sustainability, as its behavior under loading conditions are similar to virgin aggregate (VA) materials and can be simulated by using appropriate constitutive models for pavement design processes.

scholarly journals Rutting and moisture-induced damage potential of foamed warm mix asphalt (WMA) containing RAP

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Mohammad Ashiqur Rahman ◽  
Rouzbeh Ghabchi ◽  
Musharraf Zaman ◽  
Syed Ashik Ali
Keyword(s):  
Asphalt Pavement ◽  
Warm Mix Asphalt ◽  
Environmental Benefits ◽  
Reclaimed Asphalt Pavement ◽  
Chemical Additives ◽  
Flow Number ◽  
Damage Potential ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Wheel Tracking

AbstractDespite significant economic and environmental benefits, performance of warm mix asphalt (WMA) containing reclaimed asphalt pavement (RAP) remains a matter of concern. Among the current WMA technologies, the plant foaming technique (called “foamed WMA” in this study) has gained the most attention, since it eliminates the need for chemical additives. In the present study, the laboratory performance, namely rutting and moisture-induced damage potential of foamed WMA containing RAP were evaluated and compared with those of similar hot mix asphalt (HMA) containing identical amount of RAP. Dynamic modulus, Hamburg wheel tracking (HWT) and flow number tests were performed to assess the rutting resistance of the mixes. Also, stripping inflection point from HWT tests and tensile strength ratio after AASHTO T 283 and moisture induced sensitivity test (MIST) conditioning were used to evaluate the moisture-induced damage of asphalt mixes. It was found that MIST conditioning effectively simulates the moisture-induced damage and can capture the propensity of asphalt mixes to moisture damage more distinctly compared to AASHTO T 283 method due to application of cyclic loadings. The foamed WMA was found to exhibit higher rutting and moisture-induced damage potential due to lower mixing and compaction temperatures compared to HMA. However, the increase in RAP content was found to reduce rutting and moisture-induced damage potential for WMA. Therefore, the lower stiffness of foamed WMA may be compensated with the addition of stiffer binder from RAP.

Featuring Reclaimed Asphalt Pavement Integration in Warm Mix Asphalt towards Roads Sustainable Development

2013 ◽  
Vol 649 ◽  
pp. 242-245 ◽  
Author(s):  
Alina Mihaela Nicuţă
Keyword(s):  
Sustainable Development ◽  
Energy Saving ◽  
Asphalt Pavement ◽  
Warm Mix Asphalt ◽  
Environmental Benefits ◽  
Transport Infrastructure ◽  
Reclaimed Asphalt Pavement ◽  
Life Cycle Assessment Methodology ◽  
Road Asphalt ◽  
Reclaimed Asphalt

The evaluation of energy savings in the area of transport infrastructure entails a complex characterization of factors, attitudes and consequences. In the frame of energy saving approach, must be identified sustainable alternatives and solutions for road asphalt pavements production and exploitation. Finding innovative materials is one major objective in this process. In the present paper has been carried out an evaluation of the energetically and environmental benefits of warm mix asphalt (WMA) compositions that incorporate reclaimed asphalt pavement (RAP) and their contribution to roads sustainable development. For a proper analysis and reliable results, have been used the Life Cycle Assessment methodology and asPECT software. WMA integrating RAP are known as energy – saving and environmentally friendly asphalt roads pavements. Analyzed in a comparative perspective with hot mix asphalt (HMA) incorporating RAP, WMA would gain in results due to the decrease in mixing and compaction temperature, energy consumption and emissions but also to the increase in durability, quality and performance. The results of this comparison intended to point out an alternative that would provide an increase in the sustainability of the transport infrastructure sector.

Production, Construction, Properties, and Performance of a Test Road with High Reclaimed Asphalt Pavement Content

2017 ◽  
Vol 2633 (1) ◽  
pp. 37-45
Author(s):  
Jian-Shiuh Chen ◽  
Han-Chang Ho ◽  
Yen-Yu Lin
Keyword(s):  
Asphalt Pavement ◽  
Asphalt Mixtures ◽  
Environmental Benefits ◽  
Engineering Properties ◽  
Asphalt Pavements ◽  
Pavement Performance ◽  
Reclaimed Asphalt Pavement ◽  
Reclaimed Asphalt ◽  
Test Road ◽  
And Performance

The two primary factors that drive the use of reclaimed asphalt pavement (RAP) are economic savings and environmental benefits. However, highway agencies are concerned about the use of a high percentage of RAP in asphalt pavements. This study addressed issues related to the production, construction, properties, and performance of asphalt pavements that contain high percentages of RAP. Mixtures that contained up to 40% RAP were successfully designed, produced, and constructed after proper procedures were followed and attention to detail was paid during design, production, and construction. A separate drum for drying and heating RAP, called a parallel heating system, was used to produce high RAP content asphalt mixtures in a batch plant. Rejuvenating agents were mixed directly in a surge bin to allow the rejuvenator enough time to diffuse into aged RAP binder. Comprehensive laboratory tests were performed to evaluate the air voids, the resilient modulus, the rut depth, and the Cantabro weight loss of asphalt mixtures with high RAP content. A test road was constructed in 2014 to monitor how high RAP asphalt pavements would perform under real traffic and environmental conditions. An in-depth investigation was conducted of pavement performance, including cracking, friction, and rutting. The engineering properties of plant-produced mixtures and field cores were well correlated with the pavement performance of the test road. Test results indicated that high RAP content asphalt mixtures could perform as satisfactorily as those produced with virgin materials to meet in-service requirements.

Influence of Reclaimed Asphalt Pavement on Performance-Related Properties of Gap-Graded Rubberized Hot-Mix Asphalt

2017 ◽  
Vol 2633 (1) ◽  
pp. 80-89 ◽  
Author(s):  
Shawn S. Hung ◽  
Mohammad Zia Alavi ◽  
David Jones ◽  
John T. Harvey
Keyword(s):  
Performance Test ◽  
Hot Mix Asphalt ◽  
Asphalt Pavement ◽  
Environmental Benefits ◽  
Reclaimed Asphalt Pavement ◽  
Fine Aggregate ◽  
Reflective Cracking ◽  
Cracking Resistance ◽  
California Department ◽  
Reclaimed Asphalt

Rubberized hot-mix asphalt (RHMA) has been widely used in construction projects by the California Department of Transportation (Caltrans) for the environmental benefits of its recycled waste tires and for its improved fatigue and reflective cracking resistance. Currently, Caltrans does not permit the use of reclaimed asphalt pavement (RAP) in any gap- or open-graded rubberized asphalt mixes. However, given the cost and environmental benefits of RAP to replace portions of required virgin binder and aggregates in conventional mixes, interest is growing in the addition of some RAP to RHMA mixes as well. This study investigated concerns about this proposed practice. Three phases of laboratory testing (i.e., asphalt binder testing, fine aggregate matrix mix testing, and full-graded mix testing) were conducted to evaluate the effects of the addition of RAP into new RHMA mixes. The results indicated that the gap-graded aggregate structure of RHMA might limit the amount of RAP that could be used in the mix. Only 10% RAP by binder replacement could be achieved for the mix tested in this study, but the other specified volumetric requirements were still met. Replacement of a portion of asphalt rubber binder with age-hardened RAP binder increased the binder stiffness at low and high temperatures, which indicated enhanced rutting performance but diminished low-temperature cracking performance. Test results from full-graded mixes indicated similar trends, with improved rutting performance with the addition of RAP but also with significantly poorer fatigue and reflective cracking resistance.

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