Motorists will have a much smoother ride on Interstate 20 when the Southern Roadbuilders Division of APAC-Georgia Inc. completes a $15.3-million reconditioning project in Columbia and McDuffie counties.
“Interstate 20 was built in the early 1960s, and the highway had begun to show signs of significant wear,” said Brian Hall, project manager of APAC-Georgia. “As water seeped into the subgrade through the years, the subgrade had softened up, causing the concrete roadway surface to crack under the weight of traffic.”
The Georgia Department of Transportation (GDOT) had repaired several sections of the roadway through the years. But as water kept seeping through new cracks that continued to form, the deterioration finally reached the point where a more comprehensive solution was required.
GDOT awarded APAC-Georgia the contract for this extensive reconditioning project on July 27, 2001, and work began in October. The construction zone extends from mile marker 172 to mile marker 181.
“We began by establishing a clear zone 50 ft. from the center line of the outer lanes and 30 ft. from the center line on the median,” Hall noted. “To handle this work, we utilized two Komatsu 220 excavators with appropriate attachments.
“We then moved on to the paving portion of the project,” he added. “Basically, we did that work in four stages, moving from the inside out on both the eastbound and westbound sides of the highway.”
APAC-Georgia began by bringing in PP&S as its subcontractor to mill the inside shoulder of the roadway. PP&S relied on a Roadtec milling machine to complete this portion of the project.
The base crew from APAC-Georgia then spread GAB stone, obtained from Rinker Materials, to bring the subgrade up to the proper thickness. The base crew utilized a Blaw-Knox widening spreader to distribute the material, and two Caterpillar CS431C vibratory rollers to compact it to the desired 10-in. (25 cm) thickness. In the process, workers also widened the inside shoulder from 4 to 6 ft. (1.2 to 1.8 m).
As the base crew completed its work, the APAC-Georgia paving crew began building up the new shoulder surface. Workers began by putting a 4-in. (10 cm) layer of A-base asphalt atop the subgrade, then topped it off with a 2-in. (5 cm) layer of .5-in. (1.25 cm) surface mix. GDOT mandated a polymer mix asphalt for the surface of the inside shoulder because plans called for shifting traffic to that shoulder during subsequent phases of the project. To apply the asphalt, with materials provided by Martin Marietta, paving crews utilized a Roadtec RP 180-10, two Ingersoll-Rand DD90 drum rollers and an Ingersoll-Rand pneumatic roller. APAC-Georgia also equipped each crew with a Broce broom or a Lay-Mor sweeper to assist with clean-up chores.
“After completing work on the inside shoulder, we did select rehabilitation work on the inside traffic lane,” Hall said. “We worked closely with GDOT’s Project Engineer Michael Taylor and other department officials to determine which slabs we needed to replace.”
APAC-Georgia utilized its Komatsu 220 excavators and four John Deere 644 loaders equipped with forks to remove the slabs and load them into dump trucks supplied by Jeffrey Harris Trucking of North Augusta, SC, and Dwight Tucker Trucking of Gibson, GA. To supply replacement concrete, APAC-Georgia set up a REX Model S concrete plant on Highway 150, just off I-20.
After completing work on the inside lanes, APAC-Georgia turned its attention to the outside traffic lane. Again, workers removed concrete slabs with Komatsu 220 excavators and John Deere 644 loaders. By the time they had finished, workers had moved more than 150,000 sq. yds. (125,419 sq m) of concrete slabs.
In some places, APAC-Georgia also had to undercut the existing subgrade and bring it back up to the required 9-in. (23 cm) thickness. To facilitate the process, workers removed guardrails in these areas and ran side dump trucks filled with new base material along the shoulders of the road. APAC-Georgia then utilized a Caterpillar 12H motorgrader to level the new base material and compacted it with Caterpillar CS431C vibratory rollers in accordance with GDOT specifications.
When all this work was completed, a crew of 24 people moved in to set mesh and dial bars in advance of the concrete paving crews.
“Keeping the prep crew ahead of the paving crew represented a major challenge,” Hall explained. “The paving crew moved at a fairly rapid pace, covering an average of 1,800 yds. each day. In all, the project will require nearly 40,000 cu. yds. of high-strength concrete.”
Workers utilized a Gomaco 2800 concrete paver and a CMI TC420 curing compound machine to complete the new concrete traffic lanes. “We kept nine to 12 concrete trucks running all the time,” Hall said. “Because of traffic backups, we initially had concerns that delays might allow the concrete to set up in our trucks. But we succeeded in limiting the concrete’s travel time by setting up temporary acceleration and deceleration lanes and using the medians as a turnaround point.”
After completing the outside traffic lanes, APAC-Georgia began milling the outside emergency lanes and preparing the subgrade there for paving. The company will utilize standard Superpave mix for that portion of the project. The paving crews will rely on the same equipment to create the new surface for the outside emergency lanes that it used on the inside emergency lanes. In all, the new emergency lane surfaces will require approximately 40,000 tons (36,287 t) of asphalt.
In addition to the challenges of dealing with normal traffic on I-20, APAC-Georgia had to cope with some unique scheduling requirements imposed by GDOT. Because of the construction zone’s proximity to Augusta, GDOT required the company to have all traffic lanes open for two weeks in April to accommodate the Master’s Golf Tournament. Similarly, the department required APAC-Georgia to keep all lanes open during the week of July 4.
“If we could have continued work during those weeks, we certainly could have completed the job faster,” Hall noted. “But as it is, we still expect to finish well ahead of schedule.”
The last phase of the project will come later this summer, when Peek Paving and Marking arrives to put new lines on the interstate. It will utilize a new reflective tape manufactured by 3M Company and mandated by GDOT for the new highway markings.
