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This report presents the results of a research project to investigate the design and performance of thin and ultra-thin whitetopping. To learn more about whitetopping, the Minnesota Department of Transportation (Mn/DOT) constructed a whitetopping project consisting of six test sections on I-94 at a research facility and three test sections at intersections on US-169 at Elk River. This report includes a brief description of Mn/DOT history with whitetopping and a detailed description of the construction of the heavily instrumented whitetopping test sections on I-94 and US-169. All concrete mixes contained either polypropylene or polyolefin fibers. The compressive strength, flexural strength, Poisson's ratio, and elastic modulus were measured for these mixes, and the results are provided.

This presentation pertains to report 2014RIC14, Integrated Tools for Pavement Design and Management.

Cracking of the concrete decks on newly constructed bridges in Minnesota has become a significant concern. Since 2005 MnDOT has been collecting bridge deck construction and early age cracking information on a "Bridge Deck Placement Data Form." The information collected has been entered into a database, along with early age crack surveys, concrete mix design information and concrete testing information. There currently is information on over 120 bridges stored in the database. Crack surveys were performed on 20 of the bridges contained in the database. A statistical analysis of the data, including the updated crack surveys, was performed to determine if there were any relationships between variables collected on the forms and crack frequency, type, or time of development. The analysis showed that, in general, the data collected was not sufficiently consistent to draw significant conclusions. A relationship for temperature restraint cracking for bridges with integral abutments was developed for lineal feet of cracking as a function of bridge deck age, water/cementitious material ratio, and total cementitious content. Recommendations were made for modifications to current construction practices and improving the uniformity of the data collected on the "Bridge Deck Placement Data Form" in the future, so that additional analysis could be performed with more consistent data.

Eighteen chip-sealed roadways in eight cities and counties in Minnesota were evaluated both in the field (for condition surveys and density tests) and in the laboratory (for permeability; stripping; tensile-strength ratio; asphalt film thickness; and mix properties) to evaluate factors associated with stripping in asphalt pavements under chip-seal treatments. Analysis of the test data did not support an earlier MnDOT finding that high air voids were a cause of stripping under chip seals. For those locations that did exhibit stripping; the test data did not support a direct relationship between asphalt pavement density and stripping. In addition; the research did not determine a direct relationship between incidence of stripping and site/supplier data (e.g.; bituminous mixture; contractor; geographic location; or year of construction). This observation agreed with observations made by Minnesota city/county engineers. An additional outcome of the research is the large amount of testing data developed; which is documented fully in appendices to the final report.

In 1993, two hot-mix asphalt and four whitetopping overlay test sections were constructed on low volume TH 30 in southern Minnesota. A study was undertaken to examine the performance and costs associated with the test sections after nine years of service. The field testing and evaluation are described, and the costs incurred through 2001 are tabulated. The hot-mix asphalt overlay test sections are performing up to their design expectations. Both hot-mix asphalt test sections have had routine preventative maintenance applied to them, adding to their long-term cost of operation and ownership. The whitetopping test sections are performing very well at the midpoint of their design life of 20 years. Most distresses to date are related to poor construction and materials, rather than inherent design features. Some random longitudinal cracking has occurred in areas of the whitetopping control section. The doweled test section has numerous distressed transverse joints caused by dowels near the surface of the slabs. There is virtually no faulting of the transverse joints, and the ride quality has stabilized. No maintenance has been performed on the whitetopping sections through 2001. As of 2002, the most economical overlay design in this study is a 6 inch thick bonded whitetopping. Based on recent observations, it appears whitetopping is a good performing and economical rehabilitation option for low volume roads in Minnesota.

This National Road Research Alliance (NRRA) study of MnROAD cold central-plant recycling (CCPR) sections investigated various design options for cold central plant recycling (CCPR) in low-volume road applications, where local engineers or contractors may rely on a stockpiled, single-source recycled asphalt pavement (RAP) as a quality cold-recycled layer for a paving project. Both the laboratory and field testing strove to characterize the cold-recycled (CR) layers as they performed in-situ. The field sections at MnROAD were intended to simulate low-volume road applications; therefore, the project endeavored to limit the preparation demands and characterization needs of the RAP stockpile. The laboratory tests determined that the MnROAD CCPR mixtures performed comparably to cold- recycled mixtures that were tested in other studies. Field study and observation determined that that chip-sealed CCPR lifts risk early rutting, whereas CCPR sections overlaid with 1.5" hot-mix asphalt (HMA) did not develop rutting.