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The purpose of this course is to provide training and guidelines for the use of Superpave/Gyratory mix designs by local agencies in Minnesota. Local agencies need to understand what Superpave is and is not; what it is designed to do; how it works, particularly for low volume roads; what impacts it will have on pavement and mixture design, construction, maintenance, performance and cost; and how to implement Superpave/Gyratory mixtures under Mn/DOT's specifications. This course will provide focused, state-specific information on traffic, materials, design, construction, quality management, performance and specification issues. When the term "agency" is used in these guidelines, it should be understood to refer to either a local agency or a consultant performing design work on behalf of that agency. These guidelines frequently refer to the 2004 Mn/DOT 2360 Combined specification. Specifications continually evolve and improve. The reader should be certain to use the appropriate year's specifications for a given contract, preferably the most recent."

In a partnership formed with the Minnesota Department of Natural Resources (DNR), the Local Road Research Board (LRRB) investigation 819, the Minnesota Department of Transportation (Mn/DOT), and other partners, MnROAD test cell 31 was reconstructed with a hot mix asphalt (HMA) that contained 80% (by volume) Mesabi Select Hard Rock aggregate. It marked the first asphalt mix of its kind that utilized Mesabi Select Hard Rock aggregate as both the coarse and fine aggregates of the asphalt mix in the twin cities area. The purpose of this test cell is to demonstrate to the industry that Mesabi Select Hard Rock can be used to produce a HMA mixture meeting Mn/DOT specifications. It also demonstrates that the mixture can be placed like other HMA mixtures, and through instrumentation installed at the MnROAD site, its performance can be documented and quantified.

Mineralogical analyses were performed on the Mesabi Select aggregate taken from a stockpile (-1 inch size) at MnROAD comprised of crushed material obtained from the top 25 feet of the 'Lower Cherty' member, or LC-8 bed (LC-6 bed in NRRI study), of the United Taconite mine near Eveleth. The material was utilized in asphalt (cell 32) and concrete pavement (cell 54) constructed at MnROAD's low volume loop.

“D”-cracking and other forms of aggregate-related freeze-thaw damage have often been associated with concrete pavements in Minnesota. The best approach for preventing these types of distress is to avoid using aggregate sources that are known to be susceptible to freeze-thaw damage in concrete applications. The most widely accepted methods of evaluating aggregate freeze-thaw durability involve the preparation and freeze-thaw testing of concrete beams that contain the aggregate in question. These tests are generally time-consuming, sometimes requiring months to complete, and often require the use of expensive equipment and/or highly skilled operators. Furthermore, the variable nature of many aggregate sources necessitates frequent testing to ensure the adequate freeze-thaw resistance of material being produced at any given point in time. A more rapid test of aggregate freeze-thaw durability was developed under the Strategic Highway Research Program in 1994. This test, called the Washington Hydraulic Fracture test (WHFT), was relatively inexpensive and allowed a single laboratory technician to assess the freeze-thaw durability of several samples of aggregate in as few as seven working days. Broader evaluations of the WHFT revealed several deficiencies, however.

Expansion and maintenance of roadway infrastructure creates a demand for high quality paving aggregates. Taconite industry rock and tailings are a potential source of virgin paving aggregates. Currently there is limited information available for implementing these products in construction design specifications. Preliminary information of product performance within current design constraints is valuable to both state design engineers and to future pooled-fund studies. This information can identify the potential for using these products in surface courses or possibly for use in rich-bottom leveling layers. This study examined the viability of utilizing these products in the Minnesota Department of Transportation (Mn/DOT) Superpave bituminous mixture design specifications. As part of the study 40 laboratory specimens were produced from 11 asphalt mixtures and then evaluated for asphalt content, air voids, and aggregate gradation. This report summarizes the results of the laboratory mixture evaluation.

In a partnership agreement with Minnesota Department of Transportation (Mn/DOT) the Aggregate Ready Mix Association of Minnesota (ARM) constructed a Pervious Concrete sidewalk at the MnRoad facility. In this cooperation, Mn/DOT provided the location, equipment and expertise to instrument and monitors the performance of the sidewalk. ARM provided the materials needed to construct approximately 1200 square feet of sidewalk. Construction of the pervious concrete sidewalk took place on September 13 & 18, 2006. This sidewalk was constructed with three different types of pervious concretes, a colored pervious concrete (gray) mix with 3/8" minus granite aggregate (mix #1), a pervious concrete mix with 3/8" minus gravel aggregate and 5% sand (mix #2) and a pervious concrete mix with Kraemer limestone aggregate, polypropylene fibers and 5% sand (Mix #3). This last mix has been placed successfully in Iowa with mix design specifications supplied by Iowa State University. This project will help fulfill and answer the following objectives: • Demonstrate use of different Minnesota available aggregates in pervious concrete mixes • Demonstrate use of an Iowa pervious mix using sand and fibers as part of the aggregate fraction • Will wet hard, wet freeze prevent water from draining through the pervious concrete? • Will freeze thaw cycles result in pavement deterioration or frost heaving? • Will winter sanding operations be needed? If needed, will sanding prevent pervious concrete from draining? Mn/DOT will monitor sanding and salting applications. • Can a pervious concrete section handle normal sidewalk traffic and maintenance? • Evaluation of several potential quality control measures for pervious concrete including density, permeability, and compressive and flexural strength.

The objective of this project was to provide a better understanding of how various virgin aggregate and recycled asphalt pavement (RAP) mixtures for surface layers affect the performance of gravel or crushed rock roads and; with further analysis; to determine the optimal RAP content for Minnesota gravel roads. This project included a literature review; preliminary laboratory testing; economic and feasibility analysis; and two field studies. Several studies regarding the use of RAP materials for road surfaces were reviewed. Then; laboratory tests on various RAP materials; one virgin aggregate; and mixtures of RAP materials and virgin aggregate were conducted to observe the effect of RAP on the index properties of the materials and the engineering properties of the mixtures. Initially; six test sections were constructed with various surface aggregates in two locations. Virgin RAP-aggregate blends having 15% to 60% RAP contents were placed as surface aggregate. Then; three more test sections were constructed using RAP-aggregate blends having 50%; 70%; and 80% RAP contents. Several field tests; including lightweight deflectometer; dynamic cone penetrometer; scrape; and dustometer tests; were performed to evaluate the test sections. This report provides insights regarding the effect of using RAP material on surface layers to reduce the use of virgin aggregates. It was concluded that the optimal RAP content for unpaved road surfaces changes according to the properties of the materials used; testing methods; and site conditions.

Report 2019RIC04 is a course on Lightly Surfaced Roads (LSR) with the stated objectives of: -Understand Lightly Surface Road (LSR) concept -Understand the advantages and disadvantages of LSR’s -Know the LSR applications -Understand keys to a successful LSR -Be familiar with some LSR failures and ways to avoid them -Understand the LSR treatment options -Be familiar with some online selection tools

More than 50 percent of U.S. roadways are gravel roads, making them a vital part of our transportation system. One of the drawbacks and biggest complaints about gravel roads is the dust they produce when vehicles drive over them. Residents that live on gravel roads deal with the dust that settles on their homes, yards, and parked cars, potentially reducing their quality of life. Dust can also have adverse effects on air quality and the environment and reduce the safety for drivers due to impaired vision. To control the dust on gravel roads, local agencies apply various dust suppressants on their roadways, mainly calcium chloride and magnesium chloride. However, many other dust suppressant options exist. The Minnesota LRRB has developed this document, Dust Control of Aggregate Roads, A Brief Synthesis of Current Practices, to provide local agencies with a summary of research that has been completed on various dust suppressants, their effectiveness, and impacts. Results from two surveys that document dust suppressants that local agencies (within Minnesota and Iowa) use is included as well.

Representing more than half of U.S. roadways, gravel roads are a major part of the country’s road network. Dust produced by cars as they drive on unpaved roads is a major and growing complaint nationwide and among Minnesota landowners near these roads. This dust can negatively affect air quality, crop yields, quality of life and even driver safety through impaired vision.