In 2017, Alaska laid steel-fiber rubber concrete panels on Abbott Road; field tests found less rutting than nearby asphalt, while laboratory tests indicated freeze-thaw resistance

Anyone who has driven through a cold northern city at the end of winter knows how quickly a road surface can lose its shape. Wear comes from studded tires, meltwater that seeps into cracks and refreezes overnight and heavy vehicles repeatedly traveling the same wheel paths at intersections. Rutting, the formation of grooves known as ruts in the wheel paths, is a typical problem of asphalt under repeated loads.This issue has always been present in Anchorage and local engineers have been studying for a long time what surface material could withstand the stress at the intersection point and other high-traffic areas. While concrete does not change its shape, it is known for cracking due to changing temperatures. Rubber, used together with concrete, makes it more elastic, but decreases some of its mechanical properties. To compensate for it, the Alaskan researchers introduced short steel fibers. Such material was studied in the laboratory and on the real road and the results of both experiments are presented in this paper.Laboratory and cast-in-place results that preceded the road testThe first study, Use of Steel Fiber-Reinforced Rubberized Concrete in Cold Regions, appears in the U.S. Department of Transportation’s ROSAP repository with a December 24, 2017 date and it describes the research as beginning with laboratory wheel tracker and freeze-thaw testing, followed by a small experimental cast-in-place panel trial. The abstract reports that wheel tracker tests showed much lower rutting for SFRRC than for asphalt and that freeze-thaw testing showed less cracking and strength reduction than for Portland cement concrete. The team ran these laboratory tests at the University of Alaska Anchorage, where an experimental cast-in-place panel then showed little wear under traffic, a result that informed the design of the pre-cast panels for Abbott Road.Precast panel installation on Abbott Road in summer 2017The precast panels for the Abbott Road project were designed, built and installed in summer 2017. The ROSAP study says the Abbott Road installation was meant to test at full scale, on a high-traffic urban arterial road, what the laboratory and campus results had suggested about rutting, freeze-thaw durability, construction process and life cycle cost. The study also says the panels would be monitored to determine whether SFRRC could be used on roadways.Phase II field comparison with hot mix asphalt on the adjacent sectionThe research section of the Alaska Department of Transportation & Public Facilities website hosts this second report, which contains the practical field evaluation of the SFRRC. The Phase II report compared the SFRRC sections with adjoining hot mix asphalt sections. The main findings of the summary were that SFRRC road surfaces had considerable rutting resistance when compared to the adjoining asphalt samples. The freeze-thaw results were stated in the same part, which was also tested against the lab results from the earlier cited test.Planned monitoring from 2017 to 2020 and use at intersectionsThe December 2017 study covers the laboratory and cast-in-place work and the Abbott Road plan; the Phase II report documents the field comparison findings; and the broader program, scheduled to run through December 31, 2020, was set out separately. A project listing at the National Concrete Pavement Technology Center describes an experimental feature evaluation of the SFRRC installed on Abbott Road, sponsored by the Federal Highway Administration and led by researcher Carolyn Morehouse. This listing has a start date of January 1, 2017 and an end date of December 31, 2020. In addition, it states that data will be collected for three years following construction for material wear, operation and pavement conditions, with comparisons from control sites.After this period, a synopsis was to be prepared that would include recommendations on the use of SFRRC in Alaska and it might also address issues that better specification and construction and maintenance practices could have prevented. Phase II evaluated SFRRC on a public road and the research recommended its further use at highway intersections and in test sections on major arterial roads, as described in the 2023 study published in the Journal of Materials in Civil Engineering.You use AI every day. Now get your AI Quotient. Take the AIQ test.