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The Chisholm-Hibbing Municipal Airport completed taxiway repairs of deteriorated sawed and sealed joints on August 6-8, 2001. This report documents the construction procedures, techniques, and materials used. A field review of the project was completed on January 24, 2002. This report also documents the initial performance of the repairs. Transverse thermal cracking, followed by the deterioration of the hot mix asphalt at the crack, is a major problem in Minnesota. The pavement between the cracks is often in good condition. The area within one foot of the crack begins to strip and collapse inward/downward. It also can tent up in the winter due to freezing moisture in the crack area. Both situations require repair. Long-lasting, cost-effective repairs at the cracked areas are needed. The hot pour, transverse patch material is a newer material that is fast, economical and durable. This material has the potential to be widely used for transverse crack repair on airports and roads in the state of Minnesota. This report focuses on the hot pour transverse patch material.

This project introduced the use of micro surfacing as a pavement preventive maintenance surface treatment and tested different methods of using micro surfacing to correct or prevent defects in existing pavements. Micro surfacing mixtures include polymer-modified emulsified asphalt cement, a well-graded 100% crushed mineral aggregate, and mineral filler, such as portland cement or hydrated lime, with water and control additives added to control the speed of breaking and workability. Micro surfacing remains semi-liquid during mixing and placing phases and then cures chemically for a very durable asphalt surface treatment. Application and testing revealed that the fast-moving micro surfacing process minimizes the amount of down time for traffic; does an excellent job of reestablishing cross sections; fills ruts; improves ride quality; increases friction numbers; and provides an excellent background for pavement markings. It does not seal reflective cracks, has generated some concerns about increased traffic noise, and does not work favorably for smoothing humps in pavement. Overall, project selection played a key factor in the overall success of micro surfacing. A very thin surface treatment, microsurfacing cannot be expected to fix structural problems in existing pavements. One should avoid using micro surfacing on roadways that are still rutting and repair potholes before placement of micro surfacing.

This report summarizes efforts of using the disk-shaped compact tension (DCT) test to measure thermal fracture properties of asphalt mixtures on five asphalt paving projects in Minnesota during the 2013 construction season. Five construction projects throughout the state were chosen by a team of researchers at the Minnesota Department of Transportation (MnDOT) and University of Minnesota Duluth (UMD) representing differing climatic conditions, construction practices, and asphalt PG binder grades. Contractors from these varying projects provided UMD with mix design and production pills and MnDOT with loose production mix and raw materials for specimen fabrication. Testing was done to verify mixes met the required fracture energy value of 400 J/m2. If DCT results did not meet this requirement, mix adjustment recommendations were made by the research team. When recommendations were accepted, test sections with adjusted mix were paved. DCT testing was conducted on both adjusted and unadjusted production mix. Results of these efforts showed a drop in fracture energy between mix design and production for each project. The cause is not known at this time, but will be investigated in future research. Preliminary distress surveys indicated projects with mill and overlay experienced higher amounts of cracking compared to projects with reclaim or new construction. It should be noted distress surveys were conducted 9 months after initial paving, with the roadways subjected to only one season of freezing conditions. Condition of underlying pavement structure was not investigated before paving began in the cases of mill and overlays

The Minnesota Department of Transportation (Mn/DOT) is currently conducting a research project aimed at reducing longitudinal joint (Ljt) deterioration in hot mixed asphalt (HMA) pavements through improved construction techniques, preventive maintenance practices, and repair treatments. Constructing durable HMA pavements, with adequate Ljt performance, has been well documented and extensively researched, however preventive maintenance and repair treatments specific for Ljt have received little attention in the literature. It is commonly accepted that adequate density is critically important in achieving a durable HMA pavement. Insufficient density, or high air voids, usually results from the difficulty of compacting an unconfined pavement edge, and the localized area of low density creates a density gradient. Pavements with lower densities can have more interconnected air voids, leaving them more susceptible to moisture and environmental deterioration resulting in distresses such as weathering and raveling.

The Minnesota Department of Transportation (MnDOT) is currently conducting a research project aimed at reducing longitudinal joint (L JT) deterioration in hot mixed asphalt (HMA) pavements through improved construction techniques, preventive maintenance practices, and repair treatments. Constructing durable HMA pavements, with adequate (L JT) performance, has been well documented and extensively researched, however preventive maintenance and repair treatments specific for (L JT) have received little attention in the literature. The research work plan seeks to address the deterioration through improved construction, targeted preventive maintenance, and repair methods.

The goal of this research is to investigate each agencies current design method to discover similarities and differences in the way each agency designs and builds roadways for both low and high volume roads. Each agency was given design specific inputs of common climate, traffic, and existing subgrade soil (from MnROAD) and was asked to develop a design based on current design practice/standards. This paper documented the differences in construction, materials, and expectations on performance to provide and will provide a bases for future agency discussion. The initial survey contained more information that could be covered in this paper. Future goals could include the additional information for other research topics, developing possible test sections, and again to provide a common point of discussion for future efforts. This work also builds off of the efforts started with the NVF34/Nord FOU concept at the 2007 Iceland workshop.

Micro-milling provides an innovative way to rehabilitate asphalt pavements. Micro-milling uses a milling drum with more teeth and a tighter lacing pattern to create a smoother surface than the traditional milling process (about 3 times the teeth than regular milling heads). The smoother surface provides a better surface for thin overlays, ultra-thin bonded wearing course (UTBWC), chip seals, and microsurfacing.

Ultra-thin bonded wearing course (UTBWC) pavement treatment was introduced to Minnesota in 1999. This technique, in which hot mix asphalt (HMA) is laid over a heavy asphalt emulsion layer or membrane, can be used as a preventive maintenance option or surface rehabilitation technique. One of the first highways to be overlaid with UTBWC was US-169 near Princeton.

As Portland cement concrete (PCC) pavements age, longitudinal and transverse joints can exhibit signs of distress as a result of traffic loading, climatic variations, materials-related issues, and construction defects. Although only small areas are often involved, the joint distress can substantially disrupt traffic flow and increase pavement roughness, sacrificing consumer ride comfort. When immediate action is required, temporary repairs are often made using readily available materials, such as cold mix or other asphalt materials. These temporary materials are often replaced with more permanent materials to reestablish the integrity and functionality of the concrete pavement. The goal of this project is to provide a guide for agencies to establish an effective joint repair program. The final report reviews the background information explaining why this research was performed, summarizes the findings from previous similar research studies, details how the patches were constructed and how they performed, and provides a Product Matrix that includes installation requirements, equipment needed, along with the life expectancy of the products to compare and guide the reader through product selection.

The National Road Research Alliance (NRRA); a multi-state pooled-fund program; exists to provide strategic implementation of pavement engineering solutions through cooperative research. NRRA is led by an Executive Committee of state DOT partners; and supported by numerous agency and industry partner representatives. Members provide expertise to NRRA; from the selection of research topics; to communication; and implementation. NRRA consists of five project teams: Flexible; Rigid; Geotechnical; Preventive Maintenance; and Technology Transfer. The 2017 construction season at MnROAD saw construction of 35 new and unique pavement test sections. The sections; designed to address NRRA high-priority research topics; were conceived and planned by NRRA project teams. This report details development; design; and construction of each research project and the test sections supporting them. Individual study details are left to future reports generated by the individual research contracts and their respective teams.