CLOSE OVERLAY
Project Details
STATUS

In-Progress

START DATE

07/01/20

END DATE

01/31/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Peter Taylor

Director, CP Tech Center

About the research

As the highway system ages throughout the United States, there is an increasing occurrence of joint associated distress in concrete pavements. This distress can be a result of several factors, including reactive materials, fatigue from vehicle loadings, misaligned dowel bars, poorly drained joint systems, as well as attack from aggressive deicing chemicals. Since the distress occurs primarily near the joints, while the remainder of the slabs are still in serviceable condition, it is often more economical and sustainable to perform joint repairs.

The objective of this project is to produce a short technical brief and webinar containing the best practices for the repair of distressed joints in concrete pavements and overlays, particularly those used in NRRA member states. The techical brief will include causes for the distresses, as well as case histories of successful and non-successful repair methods. A one-hour long webinar will also be developed, delivered, and recorded for future reference.

Project Details
STATUS

In-Progress

START DATE

07/20/20

END DATE

07/31/22

RESEARCH CENTERS InTrans, AMPP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Ashley Buss

Faculty Affiliate

About the research

The overarching purpose of this study is to provide recommendations for keeping the pavement structure as moisture resistant as possible for the least amount of cost. Required minimum asphalt film thickness (AFT) is an important parameter when assessing the long-term durability of an asphalt mixture. Research shows higher film thicknesses create more durable mixtures. Minnesota specifications require a minimum AFT for mixture design acceptance. If the adjusted film thickness is below acceptable limits during production, large payment reductions or orders to remove and replace may result. Pavement preservation treatments are gaining momentum as cost-effective ways of enhancing pavement life. To prevent deterioration of pavements, chip seals are a proven preservation method and have been widely used in Minnesota. A Minnesota study estimated that a chip seal placed at the time of construction will be cost-effective if pavement life is extended by approximately 0.45 years. Typical life extension for chip sealed roads range 5 to 7 years. The value of AFT specifications has been debated within the paving community. This research offers an opportunity to validate current specifications, investigate the role of chip seals in pavement durability, and use lab and field data to perform a cost-benefit analysis of increased AFT and chip seals placed at 1 year. The objective of the research project is to perform a data-driven cost-benefit analysis of applying higher AFT and/or placing chip seals at 1 year of service. Data for the analysis will be collected from both laboratory performance testing and field performance. Pavement projects especially of interest are projects that incurred pay deductions due to low AFT and if/when chip seals were placed to preserve those roadways.

Project Details
STATUS

In-Progress

START DATE

05/16/19

END DATE

09/30/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

Currently, the Minnesota Department of Transportation (MnDOT) is experiencing loose nut problems. To address this issue, MnDOT has funded a research project titled, “Re-tightening the Large Anchor Bolts of Support Structures for Signs and Luminaires,” which ended in June 2018. In this project, the researchers developed guidelines with tables and charts for tightening and re-tightening anchor bolts. MnDOT will implement these guidelines. The objective of this proposed project is to verify the effectiveness of the new tightening methods, and if necessary, make adjustments or modifications to the proposed specifications. This project will also address several issues that were found during the Phase I project.

The researchers will complete the following tasks for the Phase II project:

  1. Interview MnDOT construction/maintenance crews and contractors to get their feedback on the new specifications.
  2. Visit sites where bolts are installed with new and old specifications and inspect their performances.
  3. Continue Phase I research to study the effect of snug tight, grip length, and other details.
  4. Investigate the overstressed condition under snug tight stage for smaller anchor bolts from ¾”φ to 1¼”φ, mostly used for supports for small signs, light poles, and traffic signals. Develop the specifications specifically for snug tight procedures and verifications in stress level for the smaller anchor bolts without damaging or yielding them.
  5. Continue Phase I research to provide a practical method to tighten bolts with a yield strength of 105 ksi. Generate a guideline or specification specifically for MnDOT Spec 3385, Type C anchor bolt tightening procedures.
  6. Continue the fatigue test from Phase I to study the effect of different stress ranges.
  7. Continue to monitor the sign structure at Snelling and TH 36. The researchers started the monitoring in August 2017 and have collected valuable data. Continuous monitoring will provide long-term data that will benefit not only this project, but also others related to wind load.
  8. Finalize the specifications for tightening procedures and the bolt verification form to allow on-site verification of proper installation of bolts by MnDOT construction/maintenance crews and contractors.
  9. Funded by an NCHRP IDEA project, the researchers at Iowa State University have developed a capacitance-based smart installation and monitoring system. The overhead sign structure at Snelling Ave. and T.H.36, which is currently equipped with monitoring system for Phase I research project, can be used to implement this new technology for future applications.
Project Details
STATUS

In-Progress

START DATE

12/16/19

END DATE

01/31/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE, PROSPER
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

About the research

Base stabilization additives are used to increase the strength and stiffness of road foundations in weak and susceptible soils. Numerous additives exist for improving performance of aggregate base layers, however, most independent studies have focused on non-proprietary additives. Additives are being used to stabilize base/subbase/subgrade layers, but engineering methods for pavement thickness design need to be better defined. In particular, determining granular equivalency (GE) factors for various proprietary geomaterial stabilizers will benefit the Minnesota Department of Transportation (MnDOT) and county engineers by establishing design parameter values and a means for comparing additive effectiveness and cost.

The research has three main goals: (1) evaluate the performance of selected proprietary additives by conducting laboratory and field tests; (2) prepare pavement designs and construction specifications based on the test results; and (3) analyze the benefits of additives in terms of pavement construction cost savings and long-term service life. The laboratory study will be based on ASTM/AASHTO/MnDOT test standards and designed to determine the relationships between strength, stiffness, moisture content, gradation, freeze-thaw durability, and leaching. The field testing will involve full-scale testbed construction using the most promising mix designs. Field testing will incorporate accelerated loading testing to evaluate performance of each test bed. The primary goals of this project will be to determine reliable GE factors for a variety of conditions and document performance, cost benefits, and life-cycle cost analysis. The outcome of this research will provide guidance for the selection of proprietary additives and optimized design for base stabilization of roads.

Project Details
STATUS

In-Progress

START DATE

08/20/19

END DATE

07/31/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Vern Schaefer

Interim Director, CEER

About the research

The Minnesota Department of Transportation (MnDOT) issued a tech memo in 2015 assigning a granular equivalent (GE) factor of 2.0 to multi-axial geogrids. Due to the advance of geogrid materials, this GE value may underestimate the performance benefit of geogrids, resulting in overdesigning the thickness of aggregate base layers. The mechanistic-empirical flexible pavement design program, MnPave, does not currently contain a geogrid design module. City engineers in Mankato have used geogrid manufacturer’s design methods (e.g., Tensar’s SpectraPave4-PRO) as an alternative to analyze and design such pavement structures. However, this causes an inconsistency of standards and methodologies in pavement structure designs and difficulties in quality control and quality assurance (QA/QC) testing of roads systems. The cost analysis shows that in some projects, the geogrids can reduce the thickness of aggregate base and asphalt top to make it a more cost-effective solution. A good example is Madison Avenue between Victory Drive and Trunk Highway 22 in Mankato that the city constructed around 2012.

The objective of this project is to evaluate the performance benefit and cost effectiveness of geogrid in road systems by addressing five questions: (1) What strength enhancement is offered by the use of geogrids? (2) In which layer in a pavement structure is geogrid most effective? (3) How should geogrids be in the MnPave software application? (4) How would it be possible to evaluate the effectiveness and reliability of proprietary geogrid design? (5) How would it be possible to evaluate cost versus benefits of geogrids in different soil conditions?

Project Details
STATUS

In-Progress

START DATE

08/07/19

END DATE

06/30/22

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Chris Rehmann

Assistant Professor

About the research

The research (field study) will assess persistence of KAc in soil and water, effects on biochemical oxygen demand (BOD) and dissolved (DO), and toxicity to flora and fauna.

Project Details
STATUS

In-Progress

START DATE

04/15/19

END DATE

10/31/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Başak Aldemir Bektaş

Associate Scientist, CTRE

Co-Principal Investigator
Katelyn Freeseman

Associate Director, BEC

About the research

White-Nose Syndrome (WNS) is estimated to have killed more than 5.7 million bats in eastern North America since it was identified in New York in 2006. Due to WNS and increased disturbance of habitats used by bats for roosting and foraging, there has been a growing concern about the bat population in the United States in the last decade. Due to the steep decline in bat population, the U.S. Fish and Wildlife Service (USFWS) listed the northern long-eared bat (Myotis septentrionalis) as threatened under the federal Endangered Species Act in 2015. Additional bat species are anticipated to be listed in the coming years.

During the summer months, bat species may utilize bridges as day-time roosting habitat, and may also use them as places to form maternity colonies where they give birth and raise their young. Bridge repair and replacement projects are required to follow additional regulatory requirements to avoid and minimize impacts to the bats, when protected bat species are present on bridges. Some of these requirements (e.g., timing restrictions) are challenging to implement given Minnesota’s short construction season. This project seeks to evaluate the feasibility and efficacy of deploying non-lethal ultrasonic acoustic devices in the field to temporarily deter bats from roosting on bridges ahead of construction or maintenance activities, while minimizing harm to bats and non-target species. Test sites will be located in Minnesota or areas with similar bat species and habitats.

Project Details
STATUS

In-Progress

START DATE

10/11/18

END DATE

06/30/20

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Co-Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

About the research

MnDOT is experiencing problems with loose nuts at the anchor bolts of various transportation structures including signs and luminaires. To address this issue, MnDOT funded a research project, which ended in June 2018. In this project, Iowa State University researchers developed specifications (including tables and charts) for tightening and re-tightening of anchor bolts. MnDOT will begin to implement these specifications in a project set to occur from October 2018 to December 2019.

With the to-be-obtained field performance data, this Phase II project will refine the specifications, along with completing other needed research to complete the specifications with regard to snug tight conditions, alternative bolt materials and sizes, grip lengths, continuing fatigue tests, collecting monitoring data, etc. All results will help to complete bolt tightening and re-tightening procedures and specifications that will eliminate or minimize problems associated with loose anchor bolt nuts in MnDOT structures, which will save construction and maintenance costs while simultaneously improving the safety of the traveling public.

The findings from this project will be proposed to the AASHTO T-12 Committee to change the bolt tightening procedures.

Project Details
STATUS

In-Progress

START DATE

06/14/16

END DATE

04/30/19

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

About the research

Diamond grinding of portland cement concrete (PCC) highway surfaces, a maintenance operation carried out to extend the pavement service life, generates a high-pH and high alkalinity slurry (water, concrete, and aggregate residue), referred to as concrete grinding residue (CGR). The long-term impact of CGR slurry on soil properties (pH and infiltration) and vegetation needs to be investigated.

There is a potential for a number of ongoing/forthcoming Minnesota Department of Transportation (MnDOT) construction projects to place CGR slurries along Minnesota roadsides with potential environmental and economic implications. For instance, disposal of slurry along the “sensitive” areas of Marcoux corner (near Crookston, MN) can not only lead to reduced density of vegetation resulting in erosion problems, but can also increase the chance of invasion by exotic plant species that prefer open, well-drained soils, all of which have the potential to increase maintenance costs.

A better understanding of the potential soil chemistry impacts resulting from the application of CGR slurry may indicate preemptive soil amendments. Some previous studies have focused on investigating the influence of CGR slurry on soil pH and soil water infiltration rates in lab settings.

The objective of the proposed research is to gain a stronger understanding of the CGR effects on soil, water infiltration, and vegetation through an in-situ, statistically rigorous study that will analyze inslope and/or backslope soil samples and assess soil and vegetation properties before and after placement of the CGR.

Project Details
STATUS

In-Progress

START DATE

12/21/17

END DATE

02/28/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Peter Taylor

Director, CP Tech Center

About the research

Mixture proportioning generally uses a recipe based on a previously produced concrete, rather than adjusting the proportions based on the needs of the mixture and the locally available materials. As budgets grow tighter and environmental regulations increase, an emphasis on lowering the carbon footprint, is focusing attention on making mixtures that are more efficient in their usage of materials yet do not compromise engineering performance. A means of reducing environmental impact is to reduce the amount of binder in the mixture.

MnROAD is planning to construct several cells using reduced cementitious content mixtures, with the aim of monitoring the constructability and longevity of the concrete. The proposed work has been designed to identify the behavior and performance of concrete paving mixes with low cementitious content, i.e., between 475 to 500 lb/CY, and lower cementitious content, i.e., 430 to 470 lb/CY.

The objectives of this study include:

  • Investigate the early-age characteristics (i.e., placement issues, slow strength gain) of concrete paving mixes containing low and lower cementitious content
  • Assess causes of, or potential for, durability issues with very low cementitious content
  • Identify effect of reduced cementitious content on long term serviceability and economics of concrete pavements (i.e., benefits of reduced shrinkage)
  • Develop recommended specifications, mixing, and placement practices for the use of very low cementitious content concrete paving mixes
TOP