Research

Evaluating the Performance of a Typical New England Asphalt Mixture Designed Using Asphalt Binders Modified with Re-refined Engine Oil Bottoms (REOB)

NETC 13-2:HMA Mixtures Containing Recycled Asphalt Shingles (RAS): Low Temperature and Fatigue Performance of Plant-Produced Mixtures

NETC 10-3:Low Temperature and Moisture Susceptibility of RAP Mixtures with Warm Mix Technology

Evaluation of the Effect of Reduced Gyratory Compaction Level on Massachusetts Superpave Mixtures

NETC 06-4:Preventive Maintenance and Timing of Applications

Using “Green” Technology to Provide a Crack Resistant Thin Overlay for Rhode Island

Field Monitoring of Experimental Hot Mix Asphalt Projects Placed in Massachusetts

Determination of the Virgin Binder Grade for RAP-HMA Mixes Utilizing High Percentages of RAP

TPF-5(146) Evaluation of Modified Performance Grade Binders in Thin Lift Maintenance Mixes, Surface Mix, and a Reflective Crack Relief Layer Mix

Evaluation of Specialized Hot Mix Asphalt Mixes for Massachusetts

Evaluating the Performance of a Typical New England Asphalt Mixture Designed Using Asphalt Binders Modified with Re-refined Engine Oil Bottoms (REOB)

Sponsor: Massachusetts Department of Transportation (MassDOT)

Performance Period: 2015-2016

Description

Re-refined Engine Oil Bottoms (REOB) is the residue from re-refining used engine oil. REOB has been used to modify a base asphalt binder in order to meet a specific target low temperature performance grade. However, the New England States have several concerns that are associated with the use of REOB in asphalt binders and asphalt mixtures.

To address these concerns, the UMass Highway Sustainability Research Center (HSRC) will conduct a two phase study. Phase I will investigate the effect of REOB obtained from two sources on the physical and rheological properties of asphalt binders obtained from two refineries. The physical and rheological properties will be measured after AASHTO specified short term and long-term aging and after extended long-term aging. In Phase II, the effect of the two REOB modified binders on the performance of asphalt mixtures after AASHTO specified short and long-term aging will be evaluated.>


NETC 13-2:HMA Mixtures Containing Recycled Asphalt Shingles (RAS): Low Temperature and Fatigue Performance of Plant-Produced Mixtures

Sponsor: New England Transportation Consortium

Performance Period: 2014-2016

Description

The goal of this research is to evaluate plant-produced HMA mixtures that contain Recycled Asphalt Shingles (RAS) to identify the critical material properties and plant operations that are needed to produce RAS mixtures with fatigue and low temperature cracking properties equivalent (or better than) typical mixtures that are produced.

The effect of plant production parameters (plant type, production temperature, mixing time, silo storage time, transportation aging, etc.) on the fatigue and low temperature cracking performance will be evaluated. Additionally, the blending of the virgin and aged RAS (and RAP) binders will be evaluated.


NETC 10-3:Low Temperature and Moisture Susceptibility of RAP Mixtures with Warm Mix Technology

Sponsor: New England Transportation Consortium

Performance Period: 2013-2016

Description

The research project presented herein will evaluate the moisture susceptibility and low temperature cracking properties of RAP mixtures produced with WMA technologies. Plant mixtures produced with varying RAP contents and warm mix technologies will be sampled. Laboratory testing will include an evaluation of mixtures susceptibility to moisture damage using one or more of the following tests: (1) AASHTO T324 “Hamburg Wheel-Track Testing of Compacted Hot Mix Asphalt (HMA)”, (2) AASHTO T-283 “Resistance of Compacted Hot Mix Asphalt (HMA) to Moisture-Induced Damage”, and (3) ratio of wet to dry dynamic modulus measured at 20ºC. Also, the low temperature cracking susceptibility will be evaluated using the following two tests: (1) AASHTO TP10-93 “Standard Test Method for Thermal Stress Restrained Specimen Tensile Strength (TSRST)” and (2) AASHTO T322 “Standard Method of Test for Determining the Creep Compliance and Strength of Hot Mix Asphalt (HMA) Using the Indirect Tensile Test Device.” Additional testing will include evaluating the effect of the different WMA technologies on the workability of the mixtures and evaluating the degree of blending between the RAP binder and the virgin binder using a procedure developed by Bonaquist.


Evaluation of the Effect of Reduced Gyratory Compaction Level on Massachusetts Superpave Mixtures

Sponsor: Massachusetts Department of Transportation (MassDOT)

Performance Period: 2013-2016

Description

In Massachusetts, Superpave mixtures have been designed following the recommended gyration levels outlined in AASHTO R35 “Superpave Volumetric Design for Hot Mix Asphalt (HMA).” This specification relates specific gyrations levels to anticipated traffic level (ESALs). In recent years, Contractors have asked MassDOT to consider reducing the level of gyrations for mixtures designed to Ndesign of 100 gyrations (ESALs 3 to <30 million). Based on discussions with Contractors, their rationale for the reduction in gyrations is related to being able to obtain density in the field with less compactive effort. MassDOT has already made changes to their specification that will assist the Contractors in meeting the field density. Specifically, MassDOT has increased the Voids in Mineral Aggregate (VMA) requirement for Superpave mixtures by 1% over what is recommended in AASHTO M323 “Superpave Volumetric Mix Design.” Increasing the VMA requirement assures a greater volume of binder in the mixture. This larger volume of binder should aid in the compaction of the mixture. However, even with this change to the VMA requirement, the current Ndesign 100 gyration mixtures (ESALs 3 to <30 million) continue to present challenges in achieving the specified in-place target density. This project will investigate the effect of reducing Ndesign on performance of typical Superpave mixtures produced in Massachusetts.


NETC 06-4:Preventive Maintenance and Timing of Applications

Sponsor: New England Transportation Consortium

Performance Period: 2013-2016

Description

The purpose of this project is to research existing best practices for pavement preventative maintenance strategies and adapt them to the unique variety of road conditions in New England (different traffic volumes, pavement materials, and northern climates). Additionally this research will attempt to outline pavement maintenance techniques and the inter-relationship with the timing of their application in New England.


Using “Green” Technology to Provide a Crack Resistant Thin Overlay for Rhode Island

Sponsor: Rhode Island Department of Transportation (RIDOT)

Performance Period: 2012-2015

Description

The objective of this project is to design and evaluate the performance of a Warm Mix Asphalt (WMA) mixture with crumb rubber as a modifier. The mixture will be used as a pavement preservation/ rehabilitation strategy that can provide a crack resistant thin overlay for Rhode Island roads.

Two mesh sizes of rubber will be used, a 40 mesh and an 80 mesh. Based on the results of the binder testing, a percentage of rubber and a mesh size will be selected to perform a mixture design using Superpave as well as performance testing for the mixture.


Field Monitoring of Experimental Hot Mix Asphalt Projects Placed in Massachusetts

Sponsor: Massachusetts Department of Transportation (MassDOT)

Performance Period: 2012-2017

Description

Massachusetts has been involved with numerous field trials of experimental Hot Mix Asphalt (HMA) mixes. In recent years, these types of mixes have included, but are not limited to: Superpave, Warm Mix Asphalt (WMA), Asphalt Rubber (AR), and Reflective Crack Relief Layers (RCRL) mixes.

Each of these experimental projects has been placed to evaluate a specific technology or design methodology. These evaluations cannot be made over a short period of time. Hence, the goal of this project is to monitor the performance of these experimental HMA mixes, and new experimental mixtures that will be placed, over a three year period in order to fully evaluate their performance in the field.


Determination of the Virgin Binder Grade for RAP-HMA Mixes Utilizing High Percentages of RAP

Sponsor: Massachusetts Department of Transportation (MassDOT)

Performance Period: 2012-2015

Description

This study was undertaken to better understand the effects of incorporating more RAP on the performance of a 9.5 mm Superpave surface course mixture. The performance and workability characteristics of the mixtures were evaluated when using two different Warm Mix Asphalt (WMA) technologies and a softer virgin binder grade. The WMA technologies used were organic and chemical based.


TPF-5(146) Evaluation of Modified Performance Grade Binders in Thin Lift Maintenance Mixes, Surface Mix, and a Reflective Crack Relief Layer Mix

Sponsor: MassDOT, NYSDOT, ConnDOT, NJDOT, NHDOT, RIDOT

Performance Period: 2006-2013

Description

A polymer modified binder is required in a high performance thin asphalt overlay mixture because it has the ability of making the thin lift more elastic under traffic and less sensitive to temperature fluctuations. These thin mixtures typically have a thickness of one inch or less and are used in applications requiring higher levels of rutting and fatigue resistance.

A total of six asphalt binders were evaluated in this study. The binders were selected by a panel of members from the state agencies participating in the study. The binders were a PG64-28 with no modification, a PG64-28 with Polyphosphoric Acid (PPA) modification, a PG64-34 modified with Styrene Butadiene Styrene (SBS), a PG76-22 modified with SBS, a PG64-22 modified with 12% Ground Tire Rubber (GTR) and a PG64-28 modified with 2.0% latex. A Superpave 9.5mm mixture was designed using each of the six binders for this study and two sources of aggregates (crushed stone and gravel).

For the majority of the binder and mixture tests, the data showed that the modified binders performed better than the non-modified binders in terms of elastic recovery and mixture performance. The majority of the analyses identified the PG64-34 SBS as the most elastic binder and most fatigue resistance mixture. Furthermore, each binder was tested to determine its low temperature cracking resistance using the Asphalt Binder Cracking Device (ABCD). Each mixture was then tested for low temperature cracking resistance using the Asphalt Concrete Cracking Device (ACCD). Mastics corresponding to each mixture were tested for low temperature cracking resistance using the ABCD. Analysis of the results showed that the AASHTO critical cracking temperature had a strong correlation with the ABCD binder and mastics results, but did not correlate well with the mixture tests. Mastic testing generally did not correlate well with the mixture test results.


Evaluation of Specialized Hot Mix Asphalt Mixes for Massachusetts

Sponsor: Massachusetts Department of Transportation (MassDOT)

Performance Period: 2008-2012

Description

Many state transportation agencies have begun exploring and implementing the use of specialized types of hot mix asphalt paving mixtures for their potential economic, performance or environmental benefits. The specialized mixtures needed for the Commonwealth of Massachusetts were identified as expanded and increased use of technologies (Warm Mix Asphalt), increased use of recycled materials (Reclaimed Asphalt Pavement [RAP], Manufactured Asphalt Shingles [MAS] and Ground Tire Rubber [GTR]), increased use of technologies and recycled materials in combination, and thin lifts for pavement preservation.

Previous research has suggested that warm mix asphalt WMA may increase mixture moisture susceptibility. Additionally, high amounts of recycled materials may adversely impact mixture stiffness and reduce mixture workability. In this study, these types of mixtures were developed and evaluated in terms of stiffness, cracking resistance, moisture susceptibility, and rutting.

Testing of 9.5 mm WMA mixtures suggested that aging time and temperature had a significant impact on moisture susceptibility performance. Development and evaluation of a 12.5 mm gap graded mixture (incorporating up to 40% RAP, GTR and WMA) and 9.5 mm pavement preservation thin lift mixtures (incorporating up to 40% RAP, 5% MAS and WMA) indicated acceptable mixture performance in terms of moisture susceptibility and rutting but decreased cracking performance.

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