Better Roads Digital Magazine
Issue link: http://read.dmtmag.com/i/165348
Turner-Fairbank Highway Research Center and the Minnesota Department of Transportation's (DOT) Minnesota Road facility were instrumental in validating the use of concrete overlays for highway applications. Concrete overlays also have been used successfully in airport facilities, streets/roadways and industrial facilities. This acceptance and increased use seemed to happen at an almost even pace in all types of applications. Concrete Over Asphalt For a number of reasons, the majority of concrete overlays are placed over existing asphalt roads. Contributing factors include the price volatility of asphaltic oil, which is tied directly to crude oil prices. The cost of asphalt has risen dramatically compared to the cost of concrete, so the competition is much closer these days. Concrete often is selected on a first-cost basis without even considering lifecycle benefits. We also are hearing the increased use of coker equipment at oil refineries is having an effect on the supply of asphaltic oil. As we understand it, the petrochemical companies are producing higher-yield fuels and industrial products, leaving less of the residual materials such as asphalt oil. We believe another factor, which will become even more prevalent, is the growing awareness and demand for sustainable construction. Sustainability research, particularly that which evaluates the pavements' lifecycle, shows concrete pavements require less fossil fuel to place. Given concrete's low- to nomaintenance requirements, those savings are even greater during a period of time because the driving surface does not have to be repaired and maintained continually. There is research to support other sustainability features of concrete, including albedo (light reflectance), reduced motor fuel requirements due to lower rolling resistance, the greater acceptance and increased use of fly-ash and slag as secondary and ternary cementitious materials and other features that favor the use of concrete to meet sustainability requirements. Most of the concrete overlays today, particularly bonded concrete on asphalt, are in the range of 4 to 6 inches. Thicker overlays are also commonplace, and it is not uncommon to see overlays that are 8 inches thick or thicker, particularly in heavy-highway and airport pavement applications. Still, there is growing interest in thinner overlays. One example is a 2-inch, bonded concrete-on-concrete overlay on Interstate 35 at the Interstate 435 interchange at Lenexa, Kansas. When a winter storm hits, your goal is to eliminate snow and ice on roads as quickly as possible. The Hi-Way Xzalt makes your streets safer, sooner, by applying a 70:30 mixture of salt/liquid with precision application technology. Improved Deicing: • Less material bounce and improved road adhesion. • Less influence from wind. • Accelerated melting process. Improved Efficiencies: • Broadcast on one, two, or three lanes. • Higher application speeds and wider spread width. • Reduced material usage and longer routes. • One-person installation or removal in under 5 minutes. 800-363-1771 • www.highwayequipment.com • © 2013 Highway Equipment Company. All rights reserved. Text INFO to 205-289-3789 or visit www.betterroads.com/info Better Roads September 2013 11 HighwayCon_BR0913.indd 11 8/29/13 1:10 PM