When replacement of concrete pavement panels is necessary in congested, urban areas, speedy construction that quickly opens the roadway to traffic is paramount. This project focuses on evaluating potential materials, mixture proportions, and placement techniques for rapid concrete panel repair in Washington state. The research team will evaluate the key technical characteristics that govern rapid and durable repairs for concrete pavement panels through both a comprehensive laboratory-based program and a field component. On the basis of the findings, they will provide recommendations on the most efficient, economical, and durable rapid concrete repair materials and methodologies, and they will develop specifications and training materials for WSDOT. The results should allow WSDOT to maximize the lifespan of its concrete pavements while limiting construction costs and traffic impacts by avoiding full-lane rehabilitation.

Principal Investigators:
Fred Aguayo, Construction Management, UW
Travis Thonstad, Civil and Environmental Engineering, UW

Sponsor: WSDOT
WSDOT Technical Monitor: Karen Carlie
WSDOT Project Manager: Mustafa Mohamedali
Scheduled completion:  September 2025

The 2022 FHWA Climate Challenge included a call for state departments of transportation and other public sector stakeholders to explore the use of life cycle assessment (LCA) and environmental product declarations (EPDs) as a standard practice to inform more sustainable pavement material and design selection and to quantify the emissions and impacts of those practices. EPDs are transparent, objective reports that communicate what a product is made of and the life cycle environmental impacts of that product. LCA and EPDs are needed to credibly inventory carbon and determine greenhouse gas emissions. In response to the Climate Challenge, and in collaboration with the Minnesota DOT and Michigan Technological University, this study is working to meet three research objectives: 1) train WSDOT and industry personnel about carbon emissions measurement and reduction, 2) collect life cycle assessment data on WSDOT paving projects, and 3) enable WSDOT to include EPDs in project procurement processes and specifications. Integrating these into WSDOT standard practices will be a critical step in decreasing the carbon footprint of its transportation infrastructure.

Principal Investigators:
Steve Muench, Civil and Environmental Engineering, UW
Kim Schofield, WSDOT
Curt Turgeon, Minnesota DOT
Zhanping You, Michigan Technological University

Subcontractors:
Headlight Inc.
WAP Sustainability Consulting

Sponsors:
FHWA
WSDOT

WSDOT Technical Monitor: Karen Strauss
WSDOT Project Manager: Jon Peterson
Scheduled completion: December 2024

Previous WSDOT studies have indicated that a majority of asphalt pavements fail as a result of cracking first. This is especially concerning with the increased use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS), both of which can become severely oxidized and brittle, which can lead to accelerated pavement cracking. WSDOT plans to implement a cracking performance test as a part of hot mix asphalt (HMA) design to improve the cracking performance of asphalt pavement and has selected the IDEAL-CT test. However, before a cracking test can be conducted on an HMA mixture, the HMA samples must be appropriately aged. One of the goals of this project is to develop an aging protocol that will accurately mimic the aging of pavement in the field at the time that cracking occurs—in Washington, typically between three and five years after overlay construction. The researchers also intend to develop a mix design procedure that will improve the cracking resistance of mixes with high percentages of RAP, RAS, and reclaimed asphalt materials. Each year WSDOT spends more than $100 million on asphalt roadways. The results of this study should increase the service lives of asphalt pavements, thereby reducing life cycle costs and also the frequency of traffic disruption during repair.

Principal Investigator: Haifang Wen, Civil and Environmental Engineering, WSU
Sponsor: WSDOT
WSDOT Technical Monitor: Steve Davis
WSDOT Project Manager: Mustafa Mohamedali
Scheduled completion: June 2023

Chip seals, used for pavement surfacing, rehabilitation, maintenance, and preservation, cover over 7,000 miles of roadway in Washington state. Chip seals (or bituminous surface treatments) involve the application of emulsified asphalt, followed by the spreading of chips and choke stone, compaction, sweeping, and application of a fog seal. The cost of a chip seal project per lane mile is far less than that of hot mix asphalt. However, an inability to accurately measure and control the percentage of chip embedment contributes to unpredictable variation in the performance of chip seal projects. A laser scanner could be used to determine the percentage of chip embedment both quickly and accurately. The device is portable and smaller than a nuclear gauge. However, even though laser scanners have shown great potential, no one has systematically evaluated this tool for use in chip seal construction. In addition, a specification for the required percentage of chip embedment and a test protocol for the laser scanner are needed.  This project will draft a specification for the appropriate percentage of chip embedment and will develop a test protocol for the use of a laser scanner in chip seal construction. The results should help prevent premature failure of chip seals and lower pavement life cycle costs.

Principal Investigator: Haifang Wen, Civil and Environmental Engineering, WSU
Sponsor: WSDOT

WSDOT Technical Monitors:
Kevin Littleton 
Kim Schofield

WSDOT Project Manager: Jon Peterson
Scheduled completion: December 2023

Although cementitious stabilization of soils offers great advantages, such as the beneficial use of on-site inferior materials and waste by-products (fly ash, kiln dust), the approach also causes material shrinkage and subsequent cracking, which limit its widespread use. This study is investigating an innovative approach that combines the self-healing effects of bacterial spores with a method of mixing the material that involves sequential hydration. The use of bacterial microcapsules has been shown to encourage self-healing of cracking in cementitious materials. Sequential hydration is an approach in which less than optimal moisture is first added to a mix for partial hydration. The partially hydrated mixture develops initial strength but exhibits low shrinkage and cracking. With a second addition of moisture, the mixture develops higher strength but also less final shrinkage strain and stress. Mixes containing bacterial microcapsules that enhance self-healing are expected to benefit immensely from sequential hydration, and that combination may produce a novel process for developing cementitious stabilization of soils with high strength and low shrinkage cracking.

Principal Investigator: Balasingam Muhunthan, Civil and Environmental Engineering, WSU
Sponsors: TriDurLE and WSDOT
Scheduled completion: September 2023

Concerns with the performance of hot mix asphalt (HMA) that contains recycled materials have recently become the focal point of the asphalt industry. Recycled materials used in HMA in Washington may include reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAS), and recycled engine oil bottoms (REOB). In the late 2000’s recycled materials use increased as the economy crashed, market competition increased and margins decreased, and virgin asphalt binder cost increased significantly. However, the impacts of that increased usage are beginning to be better understood, and transportation agencies are determining that the durability of HMA may have been compromised as a result. The primary objective of this project is to increase the understanding of the effects of recycled materials on HMA performance and durability to enhance WSDOT’s HMA materials selection, mix design process, and standard specifications. The results are intended to help WSDOT modify its overall recycled materials strategy so that it is informed by current national best practices, takes into account observable local issues and test results, and leads to more durable HMA pavements.

Principal Investigator: Steve Muench, Civil and Environmental Engineering, UW
Sponsor: WSDOT
WSDOT Technical Monitor: Joe DeVol
WSDOT Project Manager: Jon Peterson
Scheduled Completion: March 2021