Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/440012
goes down quickly in comparison to complete road replacement, which allows the road to be opened to traf- fic much quicker. "As an industry, we're trying to educate agencies and contractors about the benefits of concrete over- lays, as well as make them aware of potential applications," Davenport says. ACPA is working through its staff engineers, affiliated associations and the National Concrete Pave- ment Technology Center to provide information and technical assistance but Davenport says there's still work to be done. One example: the ques- tions raised during a recent ACPA concrete overlay webinar. "They underscored the point that we still need to get the information out there on how to take advantage of concrete overlay technology, where the overlays can be used and the keys to building them right," he says. Stringless technology can play a big part in concrete overlays, mak- ing them easier to construct. A paver can use computerized electronic guidance systems and laser technol- ogy to control overlay thickness and smoothness and make adjust- ments as it moves along. "Stringless technology is taking hold with many contractors, as it makes the work site safer and helps improve final smoothness results when applied correctly," Davenport says. "As we move forward, it is going to increase production and reduce some of the inconvenience to motorists." Roller compacted concrete Although not a new technology, roller compacted concrete (RCC) is still new to many people. It started out as a specialty product placed by specialty contractors, but there has been growing interest in its use in different applications, including turning lanes, low-volume streets and roads, parking lots, and also in limited highway applications such as on shoulders. "Roller compacted concrete is an interesting paving material," says Wayne Adaska, P.E., director of pavements at the Portland Cement Association (PCA). "It competes well with asphalt paving on cost and speed of construction. The zero-slump concrete, which uses no forms or reinforcement, is placed with asphalt-type pavers and then compacted to a high density using vibratory rollers." The key to RCC's speed of con- struction is that it is placed in much thicker layers than asphalt. Where asphalt is placed in multiple layers of 3/4 to 2 inches, RCC is placed in single, thicker layers of up to 9 inch- EquipmentWorld.com | January 2015 57 Roller compacted concrete, which is placed using asphalt-type equipment, competes well with asphalt paving on cost and speed of construction. Though the technology has been around for many years, FDR is still one of the most sustainable paving products in the market place, since it preserves everything in place.