Cold Central Plant Recycled Asphalt Pavements in High Traffic Applications

2018 ◽  
Vol 2672 (40) ◽  
pp. 291-303 ◽  
Author(s):  
David H. Timm ◽  
Brian K. Diefenderfer ◽  
Benjamin F. Bowers
Keyword(s):  
High Volume ◽  
Base Layer ◽  
Asphalt Pavements ◽  
Ride Quality ◽  
Recycled Asphalt ◽  
Test Track ◽  
Central Plant ◽  
Perpetual Pavement ◽  
Virginia Department ◽  
Cement Stabilized Base

Cold central plant recycling (CCPR) is gaining wider use in the U.S. for rehabilitating existing asphalt pavements or for new construction. Although it is used widely in lower traffic volume situations, CCPR use in high volume pavements remains an open question when considering its structural capacity and expected performance. A project completed in 2011 on I-81 in Virginia indicated CCPR may be suitable for high-volume traffic applications and was further evaluated with the construction of three CCPR test sections at the National Center for Asphalt Technology Test Track in 2012. These sections are now approaching 20 million equivalent single axle load applications and this paper documents their structural and surface performance thus far. The structural characterization indicates healthy pavements with no significant increases in measured pavement response or decreases in backcalculated moduli over time. Performance has been excellent with no cracking observed on any section, rut depths less than 0.3 inches and ride quality that has remained almost unchanged. Perpetual pavement analyses were also conducted and found that the section with a cement-stabilized base layer supporting the CCPR layer met the criteria and is likely perpetual. The other two sections, without the cement-stabilized base, did not meet the criteria and may develop bottom-up cracking. Data from the I-81 and Test Track sections enabled the Virginia Department of Transport (VDOT) to proceed with a design-build project on I-64 that will feature CCPR with a cement-stabilized base and full-depth reclamation (FDR). It is estimated that nearly 170,000 tons of reclaimed asphalt pavement will be used with over $10 million in savings.

Utilization of Cold Central Plant Recycled Asphalt in Long-Life Flexible Pavements

2021 ◽  
pp. 036119812110237
Author(s):  
David H. Timm ◽  
Brian K. Diefenderfer ◽  
Benjamin F. Bowers ◽  
Gerardo Flintsch
Keyword(s):  
Flexible Pavements ◽  
Fatigue Cracking ◽  
Base Layer ◽  
Optimized Design ◽  
Traffic Classification ◽  
Recycled Asphalt ◽  
Test Track ◽  
Reclaimed Asphalt ◽  
Central Plant ◽  
Long Life

Long-life flexible pavements are well documented and used widely across the U.S. Found in every climate zone and traffic classification, long-life pavements do not experience deep structural distresses such as bottom-up fatigue cracking or substructure rutting. Full-scale test sections, built in 2003 at the National Center for Asphalt Technology (NCAT) Test Track, provided the basis for an optimized design approach that utilizes strain distributions for long-life thickness design. These sections, containing only virgin materials, were subjected to 30 million standard axle loadings with excellent performance in terms of rutting, cracking, and roughness. In 2012, three new sections were built at the Test Track using cold central plant recycled asphalt materials as the base layer. These layers, made from nearly 100% reclaimed asphalt pavement (RAP), supported hot mix asphalt layers that also included RAP with one section featuring in-place stabilization of the existing aggregate base. This paper provides a direct comparison between the sets of sections to compare and contrast their performance histories and structural characterization, and consider their economic and environmental impacts. None of the recycled sections are exhibiting any surface deterioration, despite heavy trafficking, and the section with a stabilized base is exhibiting lower strains than established long-life pavement thresholds. The economic analysis suggested that the recycled sections can deliver similar performance at a lower average structure normalized section cost than the non-recycled sections. Furthermore, the section with the stabilized base and 76% recycled material is likely a long-life pavement and can potentially outperform the sections with no recycled content.

Construction and Performance of Fly Ash-Stabilized Cold In-Place Recycled Asphalt Pavement in Wisconsin

2000 ◽  
Vol 1730 (1) ◽  
pp. 161-166 ◽  
Author(s):  
James A. Crovetti
Keyword(s):  
Fly Ash ◽  
Base Layer ◽  
Asphalt Pavements ◽  
Ride Quality ◽  
Asphalt Emulsion ◽  
Recycled Asphalt ◽  
Structural Capacity ◽  
Performance Trends ◽  
And Performance ◽  
Aggregate Base

Cold in-place recycling (CIR) is a common rehabilitation practice used in Wisconsin to improve the ride quality and structural capacity of deteriorated asphalt pavements. In recent years, increased emphasis has been placed on incorporating stabilizers into the CIR materials to improve the structural capacity of the CIR base layer. This improvement can serve to increase the performance life of the completed pavement or to allow for a reduced hot-mix asphalt (HMA) surface thickness. The city of Mequon, Wisconsin, included asphalt emulsion and fly ash CIR stabilization over a portion of its CIR projects in 1997. Presented are the findings relating to the constructability of the fly ash–stabilized CIR pavement as well as performance trends for the CIR pavements based on distress and deflection testing results. CIR is a common rehabilitation practice used in Wisconsin to improve the ride quality and structural capacity of deteriorated asphalt pavements. In one type of CIR application, existing HMA layers are pulverized, graded, and compacted, then used as a base layer for a new HMA surface. The pulverization process is completed to provide uniformity of support to the HMA surface and to significantly reduce or eliminate the occurrence of reflection cracking of the HMA surface. In most CIR applications, pulverization is completed through the full thickness of the existing HMA layers, as well as through the top 25 to 50 mm of aggregate base. Penetration into unbound aggregate base materials aids in cooling of the bits on the pulverizer mandrel. After pulverization, graders typically are used to spread the materials to the desired width and shape. Compaction is achieved by using vibrating steel drum and pneumatic-tire rollers. The moisture content of the CIR materials is adjusted, as necessary, by surface spraying from a water tanker truck.

Mitigation of permanent deformation in base layer containing recycled asphalt aggregates

2013 ◽  
Vol 40 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Jean-Pascal Bilodeau ◽  
Guy Doré ◽  
Jonas Depatie
Keyword(s):  
Asphalt Concrete ◽  
Deformation Behaviour ◽  
Permanent Deformation ◽  
Design Procedure ◽  
Base Layer ◽  
Repeated Loading ◽  
Recycled Asphalt ◽  
Thickness Increase ◽  
Permanent Strain ◽  
Pavement Base

The use of recycled asphalt pavement (RAP) aggregates as replacement for new materials in the pavement base weakens the layer in regards to the resistance to permanent deformation under repeated loading. A mechanistic based design procedure is proposed to ensure that base layers containing RAP particles have a similar rutting behaviour to base layers made of virgin aggregates. The design procedure allows calculating an asphalt concrete thickness increase that is based on permanent deformation behaviour of base materials. The calculation approach is based on multistage triaxial permanent deformation tests performed on granular material samples with varied RAP content. The tests allowed proposing an equation that relates permanent strain rate, RAP content, and deviatoric stress, which is the basis of the design procedure. Design charts are proposed to select adequate thickness increase for the asphalt concrete layer according to the expected RAP content in the base layer and asphalt concrete modulus.

scholarly journals Long-Term Performance of Pavement Structures with Cold In-Place Recycled Base Course

2021 ◽  
Vol 16 (2) ◽  
pp. 48-65
Author(s):  
Audrius Vaitkus ◽  
Judita Gražulytė ◽  
Andrius Baltrušaitis ◽  
Jurgita Židanavičiūtė ◽  
Donatas Čygas
Keyword(s):  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Asphalt Pavements ◽  
Recycled Asphalt ◽  
Binding Agents ◽  
Pavement Structure ◽  
Pavement Structures ◽  
Base Course ◽  
Surface Distress ◽  
Foamed Bitumen

Properly designed and maintained asphalt pavements operate for ten to twenty-five years and have to be rehabilitated after that period. Cold in-place recycling has priority over all other rehabilitation methods since it is done without preheating and transportation of reclaimed asphalt pavement. Multiple researches on the performance of cold recycled mixtures have been done; however, it is unclear how the entire pavement structure (cold recycled asphalt pavement overlaid with asphalt mixture) performs depending on binding agents. The main objective of this research was to evaluate the performance of cold in-place recycled asphalt pavements considering binding agents (foamed bitumen in combination with cement or only cement) and figure out which binder leads to the best pavement performance. Three road sections rehabilitated in 2000, 2003, and 2005 were analysed. The performance of the entire pavement structure was evaluated in terms of the International Roughness Index, rut depth, and pavement surface distress in 2013 and 2017.

Review From Multiple Perspectives for the State of the Practice on the Use of Recycled Asphalt Materials and Recycling Agents in Asphalt Concrete Surface Mixtures

2021 ◽  
pp. 036119812110611
Author(s):  
Jhony Habbouche ◽  
Ilker Boz ◽  
Benjamin Shane Underwood ◽  
Cassie Castorena ◽  
Saqib Gulzar ◽  
...  
Keyword(s):  
Quality Control ◽  
Asphalt Concrete ◽  
Asphalt Binder ◽  
Concrete Surface ◽  
Lessons Learned ◽  
Multiple Perspectives ◽  
Recycled Asphalt ◽  
Recycled Materials ◽  
Continuous Quality ◽  
Virginia Department

The objective of this paper is to provide information from multiple perspectives on the current state of the practice with regard to using recycled materials and recycling agents (RAs) in asphalt concrete mixtures. This information was collected through a survey of U.S. transportation agencies and RA suppliers combined with a search of RA-related specifications and pilot projects previously constructed. Moreover, a case study describing the Virginia Department of Transportation’s experience with RAs provides a tangible example of how at least one agency is approaching the potential implementation of these technologies. This practice review was achieved by documenting the experience, lessons learned, and best practices of multiple asphalt experienced contractors and asphalt binder suppliers in the Virginia area. This paper follows a similar survey conducted in 2014 as part of NCHRP 09-58 and provides a second look at the use of RAs across North America. Not all state departments of transportation have experience with using RAs. Factors preventing the use of RAs included specification limitations, lack of expertise in processing recycled materials, supporting data, and negative prior experiences. Developing a performance-based testing framework is mandatory for the successful use of RAs. In general, good and frequent communication with the RA supplier is critical and necessary during the planning stages, the production of mixtures, and the continuous quality control by the supplier to resolve issues when they arise. Finally, a strong quality control and quality assurance-testing program should be implemented to ensure that materials meet the properties needed to produce a good-performing mixture.

Behaviour of recycled asphalt pavements at low temperatures

1991 ◽  
Vol 18 (3) ◽  
pp. 428-435 ◽  
Author(s):  
M. Sargious ◽  
N. Mushule
Keyword(s):  
Finite Element ◽  
Low Temperature ◽  
Thermal Stresses ◽  
Asphalt Pavements ◽  
Recycled Asphalt ◽  
Expected Performance ◽  
Different Types ◽  
Low Temperature Cracking ◽  
Proper Comparison ◽  
Better Than

This paper summarizes the results of a study conducted to evaluate the behaviour of recycled asphalt pavements with respect to low-temperature cracking. For this purpose, a recycled mix consisting of 45.2% reclaimed materials and 54.8% virgin materials as well as a virgin control mix were used in the research program. In the design of both mixes, their initial properties were kept as close as possible to each other to allow for a proper comparison between recycled and virgin asphalt pavements. Using mix properties that were determined experimentally in the laboratory, thermal stresses resulted from drop in temperature and the expected cracking temperatures were determined for both mixes. An experimental analysis based on laboratory tests that consider the pavement properties only as well as a more complete theoretical analysis based on a finite element computer program known as FETAB were included in this study. The program incorporates subgrade parameters, as well as pavement properties and thickness. Using these variables as inputs to the program, the expected performance of recycled and virgin asphalt pavements of various thicknesses and resting on different types of subgrade, with respect to low-temperature cracking, was studied. The results of the study indicated that recycled asphalt pavements would perform better than virgin asphalt pavements of similar initial properties. Key words: asphalt, finite element, low-temperature cracking, reclaimed, recycled, thermal stresses.

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