Performance Evaluation of Warm Mix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement
Performance Evaluation of Warm Mix Asphalt Mixtures Incorporating Reclaimed Asphalt Pavement

Author: Brian Hill

Publisher:

Published: 2011

Total Pages:

ISBN-13:

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Sustainability is a cornerstone of today0́9s engineering world. Warm mix asphalt (WMA) and reclaimed asphalt pavement (RAP) are the most prominent sustainable materials in asphalt concrete pavements. WMA is a not a new concept, however new innovations and increased usage of WMA has been spurred by the increased focus on sustainable infrastructure systems. WMA enables reduced production temperatures through the use of wax, water, or other chemical packages. The effects of reduced production temperatures include fuel use and emissions reductions, improved compaction, and possible RAP concentration increases. RAP is the primary recycled product of the aged asphalt concrete pavements and its use leads to reductions in virgin aggregate and asphalt demand. However, significant performance issues can stem from the individual integration of WMA or RAP materials in asphalt concrete. In particular, WMA technologies can increase moisture and rutting susceptibility while RAP significantly increases the stiffness of the resulting mixture. Consequently, quality performance of sustainable asphalt pavements may require the combined use of WMA and RAP to produce mixtures with sufficient stiffness and moisture and fracture resistance. This study evaluates the potential of WMA technologies and their integration with RAP. Initially, an extensive literature review was completed to understand the advantages, disadvantages, and past field and lab performance of WMA and RAP mixtures. Rotational viscometer and bending beam rheometer tests were then used to evaluate Sasobit, Evotherm M1, and Advera WMA modified and unmodified binders. Finally, virgin and 45% RAP mixtures were designed and tested to examine the rutting, moisture, and fracture resistance of WMA and HMA mixtures. The results of this experiment provided several key observations. First, viscosity reductions may not be the primary cause for the availability of reduced production temperatures for WMA technologies. Second, WMA additive properties have a significant effect upon fracture, moisture, and rutting resistance. Furthermore, the addition of RAP to WMA mixtures improved the rutting and moisture sensitivity performance as characterized in the Hamburg and Tensile Strength Ratio testing procedures.

Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios
Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios

Author: Amy Epps Martin

Publisher:

Published: 2020

Total Pages: 284

ISBN-13: 9780309481045

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"More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS) each year. Cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The TRB National Cooperative Highway Research Program's NCHRP Research Report 927: Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios presents an evaluation of how commercially available recycling agents affect the performance of asphalt mixtures incorporating RAP and RAS at high recycled binder ratios."--

Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content
Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content

Author: Randy Clark West

Publisher: Transportation Research Board

Published: 2013

Total Pages: 162

ISBN-13: 0309259134

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TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.

Evaluation of Warm Mix Asphalt Mixtures Containing RAP Using Accelerated Loading Tests
Evaluation of Warm Mix Asphalt Mixtures Containing RAP Using Accelerated Loading Tests

Author: Munir D. Nazzal

Publisher:

Published: 2011

Total Pages: 8

ISBN-13:

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This paper presents the results of a study that was conducted to evaluate the performance and constructability of warm mix asphalt (WMA) mixtures containing reclaimed asphalt pavement (RAP). Four sections were constructed at the indoor Accelerated Pavement Loading Facility at Ohio University. Aspha-min, Sasobit, and Evotherm WMA mixtures were used in the wearing course layer of the first three sections. In addition, the fourth section had a conventional hot mix asphalt (HMA) mixture, which was used as a control. Temperature was monitored during the production, placement, and compaction of WMA and HMA mixtures. Furthermore, emission tests were conducted at the asphalt plants during the production of each of the evaluated mixtures. Falling weight deflectometer (FWD) and rolling wheel tests were conducted at different temperatures on all evaluated sections. The results of this study showed that emissions were reduced during the production of the Aspha-min and Sasobit WMA mixtures by at least 50 % for volatile organic compounds, 60 % for carbon monoxide, 20 % for nitrogen oxides, and 83 % for sulfur dioxide, when compared to the control HMA mixture. In addition, although WMA mixtures were produced and compacted at much lower temperatures, they achieved better field densities than the control HMA mixture. The FWD test results showed that at 40°F (4°C) test temperature, the control HMA mixture had significantly lower stiffness than that of the WMA mixtures. However, the FWD stiffness measurement of the HMA and the WMA mixtures were statistically indistinguishable at the intermediate and high test temperatures of 70°F (21.1°C) and 104°F (40°C), respectively. Finally, the rolling wheel test results indicated that the three WMA sections, especially the Evotherm section, exhibited more rutting than the control HMA section during the post primary compaction stage. However, the rutting rate of the HMA section was higher than those of the WMA sections in the secondary stage, which suggests that the rutting difference may slowly be mitigated.

Evaluation of Nevada's Warm Mix Asphalt Mixtures with Recycled Asphalt Pavements
Evaluation of Nevada's Warm Mix Asphalt Mixtures with Recycled Asphalt Pavements

Author: Balasekaram Jayaprakas

Publisher:

Published: 2016

Total Pages: 71

ISBN-13:

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The purpose of this study is to evaluate warm mix asphalts (WMA) with recycled asphalt pavement (RAP) from Nevada. For this study, four different warm mix technologies and four different aggregate sources with two different percentages of recycled asphalt binder ratios were used. Aggregates from Lone Mountain, North Tenaya, Spanish Springs and Lockwood were used with appropriate binders for the particular climate conditions in those areas. All the aggregates were lime-marinated, as per requirement of the Nevada Department of Transportation. Advera, Evotherm 3G, Sonnewax and waterfoam were the warm mix technologies evaluated. All four WMA mixtures satisfied all the criteria for resistance to moisture damage with or without RAP for all the aggregate sources used. In terms of fatigue, the WMA mixtures showed better results than the HMA mixture. But for the rutting resistance all of the WMA mixtures showed lower values than the HMA mixtures. This was expected, even though the WMA's rutting resistance improved when RAP was added.

Mix Design Practices for Warm Mix Asphalt
Mix Design Practices for Warm Mix Asphalt

Author: Ramon Francis Bonaquist

Publisher: Transportation Research Board

Published: 2011

Total Pages: 111

ISBN-13: 0309155592

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TRB's National Cooperative Highway Research Program (NCHRP) Report 691: Mix Design Practices for Warm-Mix Asphalt explores a mix design method tailored to the unique material properties of warm mix asphalt technologies. Warm mix asphalt (WMA) refers to asphalt concrete mixtures that are produced at temperatures approximately 50°F (28°C) or more cooler than typically used in the production of hot mix asphalt (HMA). The goal of WMA is to produce mixtures with similar strength, durability, and performance characteristics as HMA using substantially reduced production temperatures. There are important environmental and health benefits associated with reduced production temperatures including lower greenhouse gas emissions, lower fuel consumption, and reduced exposure of workers to asphalt fumes. Lower production temperatures can also potentially improve pavement performance by reducing binder aging, providing added time for mixture compaction, and allowing improved compaction during cold weather paving. Appendices to NCHRP Report 691 include the following. Appendices A, B, and D are included in the printed and PDF version of the report. Appendices C and E are available only online.

Performance Evaluation of Foamed Warm Mix Asphalt Produced by Water Injection
Performance Evaluation of Foamed Warm Mix Asphalt Produced by Water Injection

Author: Ayman Ali

Publisher:

Published: 2013

Total Pages: 201

ISBN-13:

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In recent years, a new group of technologies has been introduced in the United States that allow producing asphalt mixtures at temperatures 30 to 100oF lower than what is used in traditional hot mix asphalt (HMA). These technologies are commonly referred to as Warm Mix Asphalt (WMA). From among these technologies, foamed WMA produced by water injection has gained increased attention from the asphalt paving industry in Ohio since it does not require the use of costly additives. This type of asphalt mixtures is advertised as an environmentally friendly alternative to traditional HMA and promoted to have better workability and compactability. In spite of these advantages, several concerns have been raised regarding the performance of foamed WMA because of the reduced production temperature and its impact on aggregate drying and asphalt binder aging. Main concerns include increased propensity for moisture-induced damage (durability) and increased susceptibility to permanent deformation (rutting). Other concerns include insufficient coating of coarse aggregates, and applicability of HMA mix design procedures to foamed WMA mixtures. This dissertation presents the results of a comprehensive study conducted to evaluate the laboratory performance of foamed WMA mixtures with regard to permanent deformation, moisture-induced damage, fatigue cracking, and low-temperature (thermal) cracking; and compare it to traditional HMA. In addition, the workability of foamed WMA and HMA mixtures was evaluated using a new device that was designed and fabricated at the University of Akron, and the compactability of both mixtures was examined by analyzing compaction data collected using the Superpave gyratory compactor. The effect of the temperature reduction, foaming water content, and aggregate moisture content on the performance of foamed WMA was also investigated. Furthermore, the rutting performance of plant-produced foamed WMA and HMA mixtures was evaluated in the Accelerated Pavement Load Facility (APLF) at Ohio University, and the long-term performance of pavement structures constructed using foamed WMA and HMA surface and intermediate courses was analyzed using the Mechanistic-Empirical Pavement Design Guide (MEPDG). Based on the experimental test results and the subsequent analyses findings, the following are the main conclusions made: In general, comparable laboratory test results were obtained for foamed WMA and HMA mixtures prepared using 30°F (16.7°C) temperature reduction, 1.8% foaming water content, and fully dried aggregates. Therefore, the performance of the resulting foamed WMA is expected to be similar to that of the HMA. Surface foamed WMA mixtures had comparable rutting performance in the APLF to that of the HMA mixtures. This was also the case for intermediate foamed WMA and HMA mixtures. These results indicate the field performance of the foamed WMA mixtures is similar to that of the HMA mixtures.

Evaluation of Warm Mix Asphalt Technologies and Recycled Asphalt Pavements in Truckee Meadows, Nevada
Evaluation of Warm Mix Asphalt Technologies and Recycled Asphalt Pavements in Truckee Meadows, Nevada

Author: Cristian Diaz Montecino

Publisher:

Published: 2013

Total Pages: 110

ISBN-13:

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This study evaluated the properties and laboratory performance of hot mix asphalt and warm mix asphalt mixtures with different levels of recycled asphalt pavements content. The rheological properties were evaluated for virgin and recovered recycled asphalt binders. The mixtures were evaluated for their resistance to moisture damage and permanent deformation.