Many state, county, and municipal highway agencies have experienced the formation of bumps when placing single-lift overlays or the first lift of a multiple lift overlay. These bumps are produced at the location of a previously-existing crack, and even then almost exclusively when the crack has been sealed prior to the overlay. When such bumps are not covered with a subsequent lift, what remains is often a rough ride on a newly-overlaid roadway.
This paper describes the effects of crack sealant material type and the geometry (shape) of the routed cracks in the existing surface on the formation of bumps in bituminous overlays. A matrix of four sealant type treatments and six geometries was designed, and implemented in a test section in Jackson County, Minnesota. The overlay on the test section was constructed in September 2007.
The results of this investigation indicate that cooler pavement surface temperatures, no overband, hot-poured crumb rubber and hot-poured elastic sealants provided the best resistance to the formation of bumps in overlays.
Content Note: This is the author’s version of a work that was accepted for publication in the Transportation Research Record: Journal of the Transportation Research Board, Issue Number: 2108, Publisher: Transportation Research Board ISSN: 0361-1981. The final version can be found at https://doi.org/10.3141/2108-08.
St. Louis County performed two HMA reconstructions on portions of County State Aid Highways during 2004 and 2005; CSAH 4 south of Biwabik, and CSAH 16 east of US Highway 53. The county saw differences in initial cracking performance and identified the two roads as potential research sections in 2005. Both projects were HMA reconstructions consisting of two 12-ft driving lanes with 6-ft shoulders. 24 in. of select granular modified (less than 7 percent passing the #200 sieve) was placed above the natural soil, followed by 6 in. of class 5 base material, and 5.5 in. of bituminous pavement. The bituminous pavement was constructed as 2.5 in. base lift, 1.5 in. binder lift, and 1.5 in. wear course lift. The recycled Asphalt Pavement (RAP) for the two projects all came from CSAH 16 millings. Bituminous mixtures were designed using Marshall MV criteria.
This study is a continuation of Report 2009-15, "Best Practices for RAP Use Based on Field Performance."
This is a project summary of the research that went into Report 2013-15, " Recycled Asphalt Pavement: Study of High-RAP Asphalt Mixtures on Minnesota County Roads."
This project evaluated the field and laboratory performance of Recycled Asphalt Pavement (RAP) and Fractionated Recycled Asphalt Pavement (FRAP) test cells at the Minnesota Road Research project (MnROAD) between 2008 and 2012. Project scope included: developing specifications, construction of FRAP and RAP test cells at MnROAD, field performance evaluations, and laboratory testing of binders and mixtures on 11 test cells.
The final report was published as Report 2012-39, " MnROAD Study of RAP and Fractionated RAP."
In Minnesota the transition from winter to spring is normally accompanied by the formation of potholes and other distresses as streets and highways weaken and adjust to warmer conditions. At times the extent of this seasonal deterioration can be so vast that maintenance crews are required to give full-time attention to the problem. Patching often continues, or is repeated, as the seasons pass from spring to fall.
During winter and early spring agencies often use “cold mix” asphalt for patching, and eventually return to “hot mix” as soon as bituminous plants can be activated. The
effectiveness of these standard materials depends largely on the level of effort that patching crews can devote to site preparation and material placement.
In the spring of 2011, the cities of Bloomington and Minnetonka, Minnesota collaborated on a field investigation of the installation and field performance, of two “mastic” patching materials along with standard patches that were applied at the same time. The investigation was funded by the OPERA program and normal maintenance budgets. Mn/DOT Road Research assisted in documenting the installation and conducting autumn performance evaluations.
An Otta seal is an asphalt surface treatment constructed by placing a graded aggregate on top of a thick application of relatively soft bituminous binding agent. Minnesota has used emulsified asphalt exclusively (HFMS-2s). The binder works its way into the aggregate with rolling and traffic. In comparison to other surface treatments, material and construction specifications are not as strict. Local aggregates that would not meet the requirements for high quality paving aggregate are often used in Otta seals.
This report documents study of the field performance of an inlay type thermoplastic pavement marking material along with the two-year-old bituminous pavement to which it was applied. Evaluation included physical performance of the product and the effect on overall durability of the pavement surface. The installation was performed in May, 2006 on a bituminous test cell at MnROAD’s Low Volume Road. 524 square feet of inlaid thermoplastic pavement marking material were installed on a surface of 4 in. Superpave hot mix asphalt, including one segment installed along 100 ft of left wheel path of a lane that received standard truck load configurations, and two crosswalks that received load configurations that varied by lane. During the period between May 16, 2006 and August 1, 2007 Cell 26 received 6,809 and 2,003 repetitions of the standard 80K and overloaded 102K truck configurations respectively. The installation was a decorative treatment, not a retrofit of longitudinal lines on the existing pavement.
This paper was submitted to the Transportation Research Board for the 2009 Annual Meeting.
The two primary types of crack sealing methods commonly used in Minnesota include: ROUT AND SEAL and CLEAN AND SEAL. The ROUT AND SEAL method is preferred on transverse cracks less than ¾” wide. The clean and seal method is recommended for longitudinal cracks, or if the cracks are too numerous or too large for the route and seal method. Crack Sealing is intended to prevent moisture from entering the base and subgrade, which can weaken the pavement’s subsurface structural layer and contribute to pavement deterioration. Sealing the pavement cracks and preventing the intrusion of moisture can be expected to extend the pavements’ service life and slow the rate of deterioration.
