Chemistry can make all the difference in asphalt paving. Not the chemistry of the asphalt mix, but the chemistry of the crew doing the work.
Every company in the industry has access to the same basic tools, yet some paving companies get better-quality pavements out of them. Lindy Paving wasn’t using any miraculous, custom-made machinery (at least none they told me about) to pave 7 miles of I-79, yet the job won Lindy its third Sheldon G. Hayes Award since 2005. The award, presented by the National Asphalt Pavement Association, goes to the top asphalt paving job in the country.
Lindy’s latest award-winning project was sort of a turnaround assignment. The 7-mile stretch was considered the worst interstate pavement in Pennsylvania by the Pennsylvania Department of Transportation (PennDOT). When the reconstruction was finished, PennDOT hailed it the smoothest ride in the state.
“The guys did really well on some of the lower lifts,” Dan Ganoe, operations manager for Lindy Paving, headquartered in New Castle, Pa., told Roads & Bridges. “They realized that also, and that just got everybody that much more focused and excited about it, because they knew they really had the potential to hit some extraordinary numbers.”
The numbers Ganoe referred to are International Roughness Index (IRI) values. Before rehabilitation, the highway had an IRI of 243 in./mile on a scale on which 70 is good. After rehabilitation, the highway had an average IRI of 27.5 in./mile on the northbound lanes and 29.2 in./mile on the southbound lanes.
The IRI of a road is measured along a single wheel path and is a measure of the accumulated vertical suspension movement of a simulated generic vehicle.
Exchanging information on the job is one of the keys to the whole process, according to Joe Conti, quality control manager for Lindy Paving. A ride technician follows behind the pavement compactors with a profilometer to check the smoothness of each course of hot-mix asphalt that goes down.
“Those guys that are operating that paver and the roller operators and everybody involved is interested in seeing those [smoothness] numbers,” Conti told Roads & Bridges, and the company wants the crew to have the numbers as feedback on how they are doing and incentive to do better.
Four courses in all were laid by Lindy over the top of the old concrete pavement after it had been cracked and seated. The old pavement was 10 in. of concrete that was 30 years old and showing its advanced age.
The crack-and-seat procedure uses a guillotine-type hammer to put hairline cracks into the concrete and then a 40-ton rubber-tire proof roller to make sure the cracked concrete pieces are securely grounded. The crack-and-seat part of the job was subcontracted to Antigo Construction Inc., Antigo, Wis.
“The process is you come in and crack the pavement enough to basically remove the rigidity of it, keep it from acting like a slab,” explained Ganoe. “That’s the starting platform for our asphalt pavement structure.”
The mainline asphalt pavement structure consisted of a 10-in. base course with 37.5-mm aggregate and PG 64-22 binder. The base was covered with another 4-in. base course with 25-mm aggregate and PG 64-22 asphalt cement, then a 2.5-in. binder lift with 19-mm aggregate and PG 76-22 and finally a 1-in. wearing course with 9.5-mm aggregate and a PG 76-22 binder.
Lindy laid a total of 308,435 tons of hot-mix asphalt on the roadway, which had two 12-ft lanes in each direction with 10-ft shoulders on the outside and 4-ft shoulders in the median.
The typical paving train consisted of a Caterpillar 1055 paver being fed by a Roadtec Shuttle Buggy to avoid bumping the paving machine with an asphalt delivery truck. The paver was followed by an array of three Sakai high-frequency rollers, usually running at high frequency to stay as close to the paver as possible.
“Something we do that’s sometimes considered unusual is that we pave the 10-ft shoulder first,” Conti said, “and work across to the travel lane, passing lane and 4-ft shoulder. By doing that, the 10-ft shoulder acts as a landing area for our rollers at the end of their passes. When we’re paving in the travel lane, they have somewhere to roll off and end their passes. That eliminates any possibility of there being any displacement under the drum, which could lead to an imperfection or a small bump in the mat.”
The only unsupported edge the technique allows is at the very outside edge of the shoulder.
Ramped up paving
Lindy’s work was only part of a larger project that involved all of the bridges and ramps along that stretch of interstate. Lindy worked with PennDOT to coordinate their work with the work being done on the ramps and bridges.
“When it came to the ramps, we were able to time our work so we came through there at off-peak times,” said Ganoe, “and we could actually close the ramps in order to continue paving straight through and eliminate transverse joints.”
The bridges actually provided a convenient stopping and starting place for Lindy’s mainline paving. The crew could pave from one end of the project to a bridge or from one bridge to another without stopping, once again eliminating transverse joints.
“We set up everything—trucking and plant scheduling and everything—to accommodate that,” said Conti.
In that manner, Lindy could cover 5 miles or more, maybe jumping several bridges, in a shift, and the company at times ran a day shift and a night shift to stay on schedule.
The hot-mix material was supplied by Lindy’s stationary Gencor 600-ton/hr plant at Neville Island, which is near Pittsburgh and only 5 or 6 miles away from one end of the jobsite, so no extraordinary measures had to be taken to make sure the mix arrived at the jobsite in good condition.
The Neville Island plant has the advantage of “quick-draw” silos, which can make three simultaneous drops into the front, rear and middle of a truck without having to move the truck.
“By doing so, you avoid making a large conical pile,” said Conti, “which reduces the chance of segregation in the truck.”
As each lift was laid and compacted, a K.J. Law profilometer measured its smoothness, and the result was relayed to the paving crew.
The final ride smoothness numbers were “tremendous,” according to Ganoe.
“Making it a little more notable, I guess, would be the fact that we attained those numbers over two separate seasons,” said Ganoe. “Not only did we get those numbers once, we came back the second season and were able to attain those again.
“With the amount of work on the job, there was just no way to physically complete northbound and southbound in a single paving season,” he added. “Our paving season in Pennsylvania goes basically from April through mid-October. So we have a relatively short window that we’re allowed to place material.”
Lindy paved the northbound lanes in 2007 and the southbound lanes in 2008.
A technician measured the density achieved with each lift using a Troxler 3440 nuclear gauge. Lindy also was required to send samples of loose hot mix and core samples of the compacted asphalt to PennDOT for acceptance. The crew reached 94% of theoretical maximum density, right in the middle of PennDOT’s 92-97% specification.
PennDOT paid Lindy 92% of the possible bonus for the job, and some of it went to the crewmembers who did the work. About 20% of the ride bonus money Lindy earns is distributed to all of the company’s employees, said Ganoe. “It helps keep the thought process and your attention on quality and trying to do the best possible job you can.
Lindy sends their crews to class occasionally, but Ganoe thinks the best training is hands-on: “I think that the best form of training we have is the day-to-day engaging yourself on the performance that you’re doing that day and making the corrections. As Joe said, the communication is key. With that communication going back and forth daily, each day these guys are making themselves better.”
“When these guys are out in the field, they’re actually cross-training,” added Conti. “Our mechanics are teaching our nuclear-gauge technicians, who are teaching our roller people, who are teaching our crewmen. They’re all sharing information and cross-training in a way that I think is pretty unique.”
Winners of this year’s Quality in Construction Awards include C.W. Matthews of Marietta, Ga.; LoJac Inc. of Hermitage, Tenn.; and C.W. Roberts Contracting Inc. of Tallahassee, Fla.
C.W. Matthews’s outstanding project was the reconstruction of S.R. 400 in Dawson and Lumpkin counties. Work included 8.8 miles of milling, resurfacing and shoulder reconstruction. Some of the asphalt used for the project included 15% recycled materials.
LoJac milled and overlaid 20 miles of I-65 in Robertson County. The company worked at night, which took careful coordination of milling and paving operations, especially since the company’s asphalt plant was located 22 miles from the work site.
C.W. Roberts won for the construction, mill and overlay of I-10 in Tallahassee.
Winners of the Quality in Construction (QIC) Award are determined by numerical scores given by pavement engineers at the National Center for Asphalt Technology on the basis of how well the contractor met the specifications and achieved density on the pavement. All the pavements that meet a benchmark figure are given the QIC Award. The year after a project wins a QIC Award, it may be considered for the Sheldon G. Hayes Award. The top-ranked projects are tested for smoothness, then visually inspected by an independent pavement consultant with many years of experience in the industry.