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This brochure accompanies Report 2010-31; Predicting the Occurrence of Bumps in Overlays.

The development of small bumps in the surface of hot-mix asphalt overlays has been a problem for state and local highway agencies for many years. Sometimes these bumps are small and are not large enough to be felt by drivers. Under many conditions, however, they can be large enough to cause ride-related problems at normal operating speeds. Under this project, a survey was conducted of local and state engineers in Minnesota responsible for highway construction and maintenance to compile corrective actions that they have used avoid these bumps and to mitigate their effects if they occur. Instrumentation sites were incorporated into this project to determine the magnitudes and profiles of temperature in the existing asphalt layer when a new layer of hot asphalt is placed on top of it. The instrumentation sites were also used to gain further information on the common practices of highway construction personnel in reducing the probability of bumps, and mitigation efforts if bumps occur. This report describes the survey, site visits, construction instrumentation, laboratory studies, and evaluation conducted by the project team. It also presents a draft booklet compiling the common practices for avoiding and mitigating bumps gathered throughout the project.

This report presents a summary of pavement preservation activities and recommended uses, expected longevity, and expected pavement life extension. It also includes some basic information intended to be used by those less familiar with pavement preservation, pavement management, life cycle cost analysis, cost estimating, contracting methods and others to help inform and educate in this important aspect of pavement engineering. Tools and techniques are presented to assist local agency engineers in evaluating costs, benefits, timing, longevity, and the decision-making process for developing an effective pavement preservation program on an individual pavement segment or over an entire network. The report includes examples using real pavement engineering data from several cities and counties in Minnesota to demonstrate topics such as activity timing and the benefits of a preventive maintenance plan rather than a reactive one. A set of guidelines was developed as part of the associated project intended to serve as reference material and as a training program.

This report presents the results of two field evaluations in rural Minnesota counties to investigate the development of bumps in asphalt overlays. The primary objective was to identify crack sealant types, reservoir geometries, and construction methods that provide a higher probability of avoiding the occurrence of bumps in an asphalt overlay. One field site evaluated various crack sealant methods and materials while holding construction methods constant, and the other site evaluated different construction practiced intended to prevent bumps while utilizing constant crack sealant methods and materials, as well as other overlay preparation methods. The results of this research indicate that there are specific types of sealant materials and methods (type of sealant, reservoir geometry) as well as specific construction activities (rolling pattern, roller type, mat temperature at rolling) that can have great impact on the formation (and prevention) of bumps in asphalt overlays.

An extensive field and laboratory project was undertaken to evaluate the applicability of the concrete maturity method to predict opening to traffic criteria for portland cement concrete paving operations in Minnesota. The field study included visits to18 paving projects in the state over a three-year period. At these projects, different sensor types were evaluated. In the laboratory study, two-inch mortar cubes were tested to develop sensitivity analyses related to the proportions of cementitious materials, water-cementitious materials ratio, and other mix components. The study also evaluated different mathematical models and their ability to predict concrete strength relative to the computed maturity. In addition, a database of concrete mixes and their associated maturity curves were developed, as well as a spreadsheet for viewing maturity curves and entering new information into the database. A draft laboratory manual and a construction specification for creating and using maturity curves were developed. The results of this project include recommendations for maturity equipment, the method and ages for testing flexural beams when developing and validating maturity curves, the use of the exponential model for maturity curves, and suggestions for a construction specification and a laboratory manual. Further data collection and evaluation should be conducted by MnDOT as the method is implemented into standard practice. Appropriate modifications should then be made to ensure the method's ability to predict traffic opening and to enhance the effectiveness of paving operations.

This report describes an extensive data collection effort, spanning five years, and the subsequent data analysis to evaluate the performance of surface characteristics on portland cement concrete pavements that have been diamond ground with various grinding configurations. The data collected were analyzed and evaluated to observe the longterm performance of the surface characteristics of noise, friction, texture, and ride quality. In addition to the basic analysis and comparison of the performance with respect to the control cell, several other studies were performed such as the correction of noise data with ambient air temperatures at the individual third-octave frequencies and evaluation of trends in the data using various statistical analysis methods. In addition, other surface characteristics were measured to provide a baseline for comparison with potential future measurements, including rolling resistance and advanced texture characteristics. The surface characteristics evaluated indicated immediate changes were effected due to the grinding activity, and that over time (and due to the application of repetitive traffic) these immediate effects were diminished somewhat, in most cases. Based on the immediate and long-term performance of the various grinding configurations, recommendations are made in the report regarding the use of the configurations and areas suggested for further research.

The Minnesota Department of Transportation and Minnesota State University, Mankato, contracted with the Technical University of Gdansk, in Poland, for a second time to conduct rolling resistance at the MnROAD facility near Albertville, Minnesota. Rolling resistance testing was conducted on most of the cells of the MnROAD mainline and the low-volume road. A relative ranking of rolling resistance among the difference surfaces at MnROAD was developed. The research team from Poland conducted the testing for a week in early May 2014. The rolling resistance data collected were analyzed and are presented in this report. Additional analyses that were conducted include a relative comparison of fuel consumption predicted with the different rolling resistance coefficients measured at MnROAD, with standard concrete and asphalt pavements as references.

This report documents the development of an analysis procedure and an associated computation tool to estimate the impact of heavy vehicles on local agency pavements. The heavy vehicles of interest are those which were not anticipated at the time the pavement structure was designed, but which cause additional damage and thus create the need for rehabilitation or reconstruction sooner than expected. These unexpected heavy vehicles could be generated by new industrial facilities, mining activities, changes in urban waste collection patterns, temporary heavy construction in a limited geographical area, or for other reasons. The tool described in this report implements the procedure, and provides users with the ability to analyze a single roadway segment (for detailed impacts estimates) or an agency's entire network (for summary statistics over the system). The tool provides estimates of the percent of originally intended life that may be used by the unanticipated vehicles, the additional pavement structure that would have been required at construction to accommodate the additional vehicles, and the additional damage that they cause. The tool is contained in a macro-enabled Microsoft Excel spreadsheet and does not need additional files or external functionality to conduct an analysis.

The Minnesota Department of Transportation and Minnesota State University, Mankato, contracted with the Technical University of Gdánsk, in Poland, to conduct rolling resistance at the MnROAD facility near Albertville, Minnesota. While the rolling resistance testing was conducted on all cells of the MnROAD mainline, the primary objective relative to this project was to obtain the rolling resistance data for Cells 7, 8, and 9 - the Portland cement concrete pavement cells with conventional and two innovative diamond grinding applications. The research team from Poland conducted the testing for a week in the middle of September, 2011. All cells on the MnROAD mainline were tested, as well as one off-site location (US 212 near Shakopee, Minnesota). The collected rolling resistance data were analyzed and are presented in this report. Additional analyses that were conducted include a comparison of the rolling resistance data to surface texture, friction, and noise. Some of the comparisons are not consistent with those measured on other pavement surfaces (in Europe), but the authors present some possible reasons for the differences.

The need to consider sustainability in design dictates that materials should be recycled and reused whenever possible. The Minnesota Department of Transportation (MnDOT) is quite progressive in allowing the use of recycled aggregates in new construction. While the use of recycled concrete aggregate (RCA) in the base course of new pavements is quite common in Minnesota and many other states; it is rarely used in the concrete pavement itself. In fact; Minnesota was one of the few states to build multiple trial projects and has one of the largest number of concrete pavements constructed using the RCA in the concrete itself. The performance of those pavements; most of which are still in service; has never been formally evaluated against similar conventional concrete pavements. This prompted the current research study. Additional objectives were to assess the current state of practice across the nation; conduct experimental investigations using RCA in concrete; assess the sustainability and in particular the economics of using RCA in concrete; and finally to provide some recommendations for guidelines on using RCA in concrete. It has been shown by the authors and other researchers that it is possible to create strong and durable concrete mixtures using RCA as coarse aggregate in volume replacement levels of natural coarse aggregate up to 100%.