WCAT was established through partnership between Washington State Department of Transportation (WSDOT), the Washington Asphalt Paving Association (WAPA), and Washington State University (WSU). The National Science Foundation (NSF) has also contributed by funding the acquisition of a material testing system (NSIT0085081). The collective investment to-date amounts to over $750,000. WCAT is accredited by the American Association of State Highway and Transportation Officials (AASHTO) under the Materials Reference Laboratory (MRL) Program.The WCAT facilities are housed in Sloan Hall, home of the Civil and Environmental Engineering department on the Pullman Campus. They occupy rooms B2, B6, B15, B16,  B17, B19, B20, B21, and B22.

 
Completed Research Project

NCHRP 04-36 Project
Characterization of Cemetitiously Stabilized Layers for Use in Pavement  Design and Analysis

The objective of this research is to recommend performance-related procedures for characterizing cementitiously stabilized pavement layers for use in pavement design and analysis and incorporation in the MEPDG.  This research will deal with material properties and related test methods that can be used to predict pavement performance.  This research is concerned with subgrade, subbase, and/or base materials stabilized with hydraulic cement, fly ash, lime, or combinations thereof and used in flexible and rigid pavements.

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NCHRP Report 789
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Completed Research Project


NCHRP 04-36 Project

Characterization of Cemetitiously Stabilized Layers for Use in Pavement  Design and Analysis


The objective of this research is to recommend performance-related procedures for characterizing cementitiously stabilized pavement layers for use in pavement design and analysis and incorporation in the MEPDG.  This research will deal with material properties and related test methods that can be used to predict pavement performance.  This research is concerned with subgrade, subbase, and/or base materials stabilized with hydraulic cement, fly ash, lime, or combinations thereof and used in flexible and rigid pavements.


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NCHRP Report 789

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Research in Progress

NCHRP 9-49A Project
Performance of WMA Technologies: Stage II--Long-Term Field Performance

The use of warm mix asphalt (WMA) technology offers significant benefits, notably, lower energy demand during production and construction, reduced emissions at the plant and the paver, and increased allowable haul distances. However, it also presents potential engineering challenges. Lower WMA production temperatures and the water injection used with some WMA technologies have raised concerns about possible rutting and moisture susceptibility of WMA pavements. Thus, facilitating the implementation of WMA technologies in the United States requires the collection and analysis of definitive information on the material and engineering properties and long-term performance of WMA pavements constructed with the wide range of WMA technologies now available.

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Research in Progress


NCHRP 9-49A Project

Performance of WMA Technologies: Stage II--Long-Term Field Performance


The use of warm mix asphalt (WMA) technology offers significant benefits, notably, lower energy demand during production and construction, reduced emissions at the plant and the paver, and increased allowable haul distances. However, it also presents potential engineering challenges. Lower WMA production temperatures and the water injection used with some WMA technologies have raised concerns about possible rutting and moisture susceptibility of WMA pavements. Thus, facilitating the implementation of WMA technologies in the United States requires the collection and analysis of definitive information on the material and engineering properties and long-term performance of WMA pavements constructed with the wide range of WMA technologies now available.


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Department of Civil and Environmental Engineering, Washington State University

PO Box 642910 Spokane Street, Sloan Hall 41, Pullman, WA 99164-2910, 509-335-2513

Completed Research Project

WSDOT Project
Optimizing Asphalt Pavement Performance for Climate Zones within Washington State

The pavements in the State of Washington have witnessed great differences in performance, depending on the climatic zones. The climate west of the Cascade Mountains is generally mild with wet winters. The climate in east of the Cascades is drier and sunnier with more extreme temperatures which often drop below freezing during winter. Studded tires are widely used in this area during winter time, creating additional damage (rutting and abrasion) to the asphalt pavements although the lower studded tire use rate in Western Washington is somewhat offset by higher overall traffic levels. The climate within the Cascade Range is generally mild in summer but much more severe in winter with frequent snow and freezing conditions. A study is needed to improve pavement performance for Eastern Washington and Mountain Passes, at a minimum, by making recommendations related to mix design and construction. 


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Completed Research Project


WSDOT Project

Optimizing Asphalt Pavement Performance for Climate Zones within Washington State


The pavements in the State of Washington have witnessed great differences in performance, depending on the climatic zones. The climate west of the Cascade Mountains is generally mild with wet winters. The climate in east of the Cascades is drier and sunnier with more extreme temperatures which often drop below freezing during winter. Studded tires are widely used in this area during winter time, creating additional damage (rutting and abrasion) to the asphalt pavements although the lower studded tire use rate in Western Washington is somewhat offset by higher overall traffic levels. The climate within the Cascade Range is generally mild in summer but much more severe in winter with frequent snow and freezing conditions. A study is needed to improve pavement performance for Eastern Washington and Mountain Passes, at a minimum, by making recommendations related to mix design and construction.



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Completed Research Project

Performance Evaluation of Hot Mix Asphalt Containing Recycled Asphalt Shingles In Washington State
Due to the increasing cost of asphalt binder and also due to environmental considerations, recycled asphalt shingles (RAS) are now being allowed to be added into hot mix asphalt (HMA). Recycled asphalt shingles (RAS) have been incorporated into hot mix asphalt (HMA) with the intent to achieve the potential benefits of cost-effectiveness and environmental sustainability without compromising the performance of the HMA. This study investigates the performance of HMA with and without RAS based on the evaluation of field cores drilled from four experimental pavement sections that were constructed in 2009 in King County of Washington State. The performance of the asphalt mixtures and the recovered asphalt binders are evaluated with respect to rutting, fatigue and thermal cracking resistance via laboratory experiments. The test results show that the rutting resistance of the mixtures as well as the recovered binders is improved by the addition of RAS. However, the fatigue and thermal cracking resistance of the mixtures is not significantly affected by the addition of RAS. The field performance survey indicates excellent conditions for all test sections after three years of service.
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Performance Evaluation of Hot Mix Asphalt Containing Recycled Asphalt Shingles In Washington State.pdf
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Completed Research Project


Performance Evaluation of Hot Mix Asphalt Containing Recycled Asphalt Shingles In Washington State

Due to the increasing cost of asphalt binder and also due to environmental considerations, recycled asphalt shingles (RAS) are now being allowed to be added into hot mix asphalt (HMA). Recycled asphalt shingles (RAS) have been incorporated into hot mix asphalt (HMA) with the intent to achieve the potential benefits of cost-effectiveness and environmental sustainability without compromising the performance of the HMA. This study investigates the performance of HMA with and without RAS based on the evaluation of field cores drilled from four experimental pavement sections that were constructed in 2009 in King County of Washington State. The performance of the asphalt mixtures and the recovered asphalt binders are evaluated with respect to rutting, fatigue and thermal cracking resistance via laboratory experiments. The test results show that the rutting resistance of the mixtures as well as the recovered binders is improved by the addition of RAS. However, the fatigue and thermal cracking resistance of the mixtures is not significantly affected by the addition of RAS. The field performance survey indicates excellent conditions for all test sections after three years of service.

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Performance Evaluation of Hot Mix Asphalt Containing Recycled Asphalt Shingles In Washington State.pdf

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Research in Progress

Novel Development of Bio-based Binder for Sustainable Construction
In the United States, 96% of roads are surfaced with asphaltic materials. Hot mix asphalt (HMA) consists of aggregate particles (coarse and fine) that are bonded together by asphalt binder at elevated temperatures. Traditional asphalt binder is residue obtained during the crude petroleum refining process. Increased environmental regulations for new drilling, dwindling existing resources, modifications to the refining process that maximize the fuel quantity while minimizing asphalt residue have increased the cost of asphalt in recent years. Petroleum-based asphalt is widely used in road and other infrastructure construction, about 30 million tons each year. High oil price and tight asphalt supply have doubled the asphalt price in the past few years in the U.S. To address these challenging problems, industries are seeking an alternative binder to replace or reduce the petroleum-based asphalt used in HMA. Because of concerns over dependence on foreign oil, high energy consumption, and climate change, non- petroleum based bioasphalt would be a plausible solution.

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Research in Progress


Novel Development of Bio-based Binder for Sustainable Construction

In the United States, 96% of roads are surfaced with asphaltic materials. Hot mix asphalt (HMA) consists of aggregate particles (coarse and fine) that are bonded together by asphalt binder at elevated temperatures. Traditional asphalt binder is residue obtained during the crude petroleum refining process. Increased environmental regulations for new drilling, dwindling existing resources, modifications to the refining process that maximize the fuel quantity while minimizing asphalt residue have increased the cost of asphalt in recent years. Petroleum-based asphalt is widely used in road and other infrastructure construction, about 30 million tons each year. High oil price and tight asphalt supply have doubled the asphalt price in the past few years in the U.S. To address these challenging problems, industries are seeking an alternative binder to replace or reduce the petroleum-based asphalt used in HMA. Because of concerns over dependence on foreign oil, high energy consumption, and climate change, non- petroleum based bioasphalt would be a plausible solution.


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Research in Progress

Evaluation of Fiber-Reinforced Asphalt Pavements

The overall goal of this project is to determine the effectiveness of using fibers in HMA to improve cracking and rutting resistance. In addition to comparing the laboratory performance of the fiber mixes, this research will investigate the mixture properties needed as inputs to the mechanistic-empirical pavement design software. In the second phase of this project, the field performance of Fiber-Reinforced Asphalt Pavements will be analyzed.

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Research in Progress


Evaluation of Fiber-Reinforced Asphalt Pavements


The overall goal of this project is to determine the effectiveness of using fibers in HMA to improve cracking and rutting resistance. In addition to comparing the laboratory performance of the fiber mixes, this research will investigate the mixture properties needed as inputs to the mechanistic-empirical pavement design software. In the second phase of this project, the field performance of Fiber-Reinforced Asphalt Pavements will be analyzed.


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Coming Project

Development of Library of Indirect Tensile Creep Compliance and Strength for ITD Pavement ME Calibration
Dynamic modulus, indirect tensile (IDT) creep compliance and strength are the three primary mechanistic properties of asphalt mix for the asphalt pavement in the AASHTOWare Pavement ME. Thermal cracking is one of dominant distresses in Northern States in the U.S. Based the NCHRP 01-40, the thermal cracking prediction by the Pavement ME is very sensitive (highest category) to the IDT creep compliance and IDT strength. Similar to the case of dynamic modulus of asphalt mix, a material library and a calibration of prediction models of IDT creep compliance and strength need to be completed before a meaningful calibration of Pavement ME can be conducted based on local materials.

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Coming Project


Development of Library of Indirect Tensile Creep Compliance and Strength for ITD Pavement ME Calibration

Dynamic modulus, indirect tensile (IDT) creep compliance and strength are the three primary mechanistic properties of asphalt mix for the asphalt pavement in the AASHTOWare Pavement ME. Thermal cracking is one of dominant distresses in Northern States in the U.S. Based the NCHRP 01-40, the thermal cracking prediction by the Pavement ME is very sensitive (highest category) to the IDT creep compliance and IDT strength. Similar to the case of dynamic modulus of asphalt mix, a material library and a calibration of prediction models of IDT creep compliance and strength need to be completed before a meaningful calibration of Pavement ME can be conducted based on local materials.


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Completed Research Project

Evaluation of Steel Slag as Hot Mix Asphalt Aggregate

Steel slag is a  co-product of the steel industry and can be used potentially as a sustainable construction material in hot mix asphalt (HMA) with proper design management. This study evaluates the performance of HMA that contains steel slag aggregate (SSA). The physical properties of SSA were assessed to determine its use in HMA. Four percentages (0%, 20%, 40% and 60%) of SSA were used, and the proposed mix design for HMA was conducted in accordance with Superpave mix design. The performance of the mixes was evaluated comprehensively in terms of studded tire wear, dynamic modulus, flow number, fracture properties at intermediate and low temperatures, and Hamburg wheel-tracking device testing. The results indicate that the addition of steel slag increases studded tire wear resistance, dynamic modulus values, thermal cracking resistance, and rutting resistance. In addition, the inclusion of SSA has insignificant effect on top-down fatigue cracking resistance, and moisture susceptibility. Based on these laboratory test results, SSA mix could be especially beneficial in the Northwest region of the United States as a surface material where studded snow tires which scour the pavement and reduce the service life of the pavement, are used. 

Report Download

Evaluation of Steel Slag as Hot Mix Asphalt Aggregate

More...

Completed Research Project


Evaluation of Steel Slag as Hot Mix Asphalt Aggregate


Steel slag is a  co-product of the steel industry and can be used potentially as a sustainable construction material in hot mix asphalt (HMA) with proper design management. This study evaluates the performance of HMA that contains steel slag aggregate (SSA). The physical properties of SSA were assessed to determine its use in HMA. Four percentages (0%, 20%, 40% and 60%) of SSA were used, and the proposed mix design for HMA was conducted in accordance with Superpave mix design. The performance of the mixes was evaluated comprehensively in terms of studded tire wear, dynamic modulus, flow number, fracture properties at intermediate and low temperatures, and Hamburg wheel-tracking device testing. The results indicate that the addition of steel slag increases studded tire wear resistance, dynamic modulus values, thermal cracking resistance, and rutting resistance. In addition, the inclusion of SSA has insignificant effect on top-down fatigue cracking resistance, and moisture susceptibility. Based on these laboratory test results, SSA mix could be especially beneficial in the Northwest region of the United States as a surface material where studded snow tires which scour the pavement and reduce the service life of the pavement, are used.


Report Download


Evaluation of Steel Slag as Hot Mix Asphalt Aggregate


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