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One of the most common maintenance activities performed on bituminous pavements by local governmental agencies relates to crack treatment. Crack treatments include .crack sealing, crack filling, and crack repair. Crack sealing is the method of placing material in a crack to create a water tight barrier, while crack filling involves coating the sides or edges of a crack in an attempt to reduce the rate of deterioration. Crack repair is more extensive than both sealing or filling and can involve fine mix' patching, tight blading, mill and repair, and overlays. Generally, rubberized materials, due to their ductile properties are considered to be crack sealants while asphalt based materials are considered fillers. This report discusses the most commonly used materials and practices used by local engineers in Minnesota to seal and fill cracks on bituminous pavements. The report is based on the results of a survey conducted by the authors in 1991. The report presents the results in several ways and summarizes the findings.

Nine experimental joint sealants were installed in a one-mile long section of Interstate 94 near Sauk Centre, Minnesota. The sealants were evaluated for five years, beginning on 1988, and compared for performance against Dow Corning 888, the only silicone joint sealant currently approved for use on transverse joints by the Minnesota Department of Transportation. The sealants tested included three silicones, one urethane, one polyurethane, one nitrile rubber, one rubberized polypropylene, one polysulfide and one hot-pour asphaltic sealant . An additional section evaluated consisted of several joints sealed with Dow Corning 888 in 1976. Inspections were generally done in the winter and summer. The sealants were evaluated based on adhesion, cohesion and effectiveness of preventing the entry of moisture and incompressibles into the joint. A goal of this research project was to identify products that would provide effective long-term performance, hopefully for up to ten years. This report describes the changes in performance of the sealants during the evaluation period. Also included is a rating procedure for quantitatively evaluating joint sealants.

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

This presentation was created to accompany Report 2016-34A, System Preservation Guide: A Planning Process for Local Government Management of Transportation Networks, published in 2016.

A retrofit scheme to widen and strengthen nail-laminated timber bridges was evaluated in this project. The scheme consists basically of laying a second, transverse layer of timbers above the existing deck, and casting a grout layer between the two wood ones to insure good force transfer. An old wood bridge was evaluated before and after it was retrofitted in order to investigate the effectiveness of the retrofit technique. In addition, three laboratory specimens, representing portions of the retrofitted bridge deck (ungrouted and grouted), were tested to investigate the strength and the effects of fatigue on the retrofitted bridge deck, and to evaluate the transverse load distribution of the original and retrofitted bridge deck. An analytical model of the retrofitted bridge deck was also developed utilizing the finite element method, the deflection and transverse distribution results from the model studies were compared favorably with the laboratory results.

Pre-wetting is an important tool in the toolbox of winter road maintenance (WRM) operations. This research project collected all available and recent information regarding pre-wetting practices through a comprehensive literature review, an online survey of WRM practitioners, interviews and case studies of nine selected agencies, and outreach to six identified equipment manufacturers/distributors. Through the synthesis of current and best practices, the project resulted in preliminary guidelines or recommendations, mainly based on trial-and-error and field experience, instead of systematic and scientific investigations. There have been many success stories of pre-wetting practice by transportation agencies in northern climates. The pre-wetted material stays on the surface longer, has less bounce and scatter, and resists traffic action. The case study agencies also reported that pre-wetting allowed them to achieve the specified level of service more quickly. A pre-wetting rate of 8–12 gal/ton is effective and 8–16 gal/ton is reasonable for increasing the speed and total ice melting capacity of solid salt and reducing the snow-pavement bond. Practitioners have reported that higher pre-wetting rates (than 10 gal/ton) can achieve better operational results, thus reducing the amount of granular salt needed. For trucks equipped with pumps to make salt slurry, a higher pre-wetting rate (30 to 50 gal/ton) can be achieved. A higher application rate should be used when there is a lower pavement temperature or a more severe snow event. All survey respondents reported the use of on-board systems to apply liquids to solids. Agencies may face initial resistance to pre-wetting from operations staff or other stakeholders, but training and information dissemination coupled with effective field trials will gradually mitigate concerns and build rapport. The project also identified knowledge gaps or research needs relevant to pre-wetting practice.

This research brief was created was part of Clear Roads project CR18-04, "Review and Summary of Pre-Wet Methods and Procedures," published May 2021.

Snowplow trucks operate in extreme conditions that take a toll on engines, wiring, controls, sensors, connectors, augers, conveyors, spinners and other parts exposed to extreme cold, wetness and corrosive materials. Consequently, winter road maintenance equipment may break down on the road. Road maintenance agencies have a range of protocols for dealing with equipment breakdown in the field, including troubleshooting via phone or radio, sending out a mechanic, or towing the truck back to the station. Most agencies would benefit from more training for operators and mechanics that would enable them to more effectively address problems that can result in snowplows breaking down on the road. This synthesis sought to identify the best practices agencies use to deal with breakdown of winter road maintenance equipment in the field; the types of experience sought by agencies in their operators and mechanics; and the maintenance and repair areas where operators and mechanics would benefit from additional focused training. A national survey of winter maintenance practitioners at state departments of transportation gathered information about best practices, common equipment failures, responses to failures, and training approaches for operators and mechanics. The results of a literature search supplemented the survey findings.

As part of this research project, a literature review, a survey of practice, field data collection, and an analysis of application rates was conducted. The literature review covered application rates, performance measures, chemical products, environmental impacts, corrosion, impacts on concrete and asphalt, agro-based products, and benefit-cost analyses. A survey of practice was conducted to gather agencies’ winter maintenance practices involving materials, predominant winter conditions, liquid application rates, experience, performance measures, and interest in serving as a study site. Agencies from different geographical regions of the United States were selected for field data collection to provide a wide range of winter conditions, road types, and resources. Data collected consisted of route information and field data in terms of weather, roadway conditions, materials, application rates, and performance measures. Seventeen agencies representing nine states submitted data from 31 routes resulting in field data for 167 storms. Ranges of application rates were identified according to pavement temperature, temperature trend, road surface condition, and materials used. Guidance was developed exclusively from field data and practitioner feedback. Guidance was developed for liquid applications, blends, and “Shake and Bake” for light snow conditions (<1 in/hr., <4” in 24 hrs.). Shake and Bake is a combination of liquid and solid applications. Application rate ranges are provided in tables by material, pavement temperature, temperature trend, and supporting information regarding field data (agencies and number of storms observed).

This research brief was created as part of Clear Roads project CR19-01, "Expanding Application Rate Guidance for Salt Brine Blends for Direct Liquid Application and Anti-icing," published December 2021,