When working the mainline, even small deviations to plan can result in significant additional expenses for the paving contractor. Nowhere is this more evident than when preparing the base and sub-base for interstate concrete paving. Deviating as little as 0.5 in. from planned grade in some areas translates into higher material yields.
“If you think about it, even a 1% higher yield on a 100,000-cu-yd job means you’ll need an additional 1,000 yd of concrete,” explained Steve Friess, general superintendent for Anthony Allega Cement Contractor Inc. With Allega paying $70.00 per yd of concrete, that’s a $70,000 overrun that can be avoided.
For the past three seasons, Allega’s crews have been working on large interstate projects around the Youngstown, Ohio, area. On these projects, the same 1% higher yield would result in two to three times more overrun than the 100,000-cu-yd example.
In 2004 and 2005, the Valley View, Ohio-based concrete contractor worked on a nearly $20 million, 3.8-mile total reconstruction job of I-76 in Mahoning County. The seven-year warranty project called for 13 in. of concrete, totaling 220,000 cu yd. Therefore, a 1% higher-than-projected material yield on this project would cost the company more than $150,000.
To keep material yield to a minimum, Allega relied on two Terex CMI 4503 Trimmer/Reclaimers from Terex Roadbuilding. The three-track design of the 4503 concentrates the mass of the machine’s weight over the cutter drum, resulting in a grade with very few deviations and more stable operation than two-track machines.
“At 425 hp, the 4503 has plenty of power to excavate up to 9 in. of base and accurately trim the hardest of stabilized base material,” said Leon “Red” Lampkin, district sales manager for Terex Roadbuilding concrete mobile equipment. “The balanced design of the machine allows it to hold grade.”
Standard grade control on the trimmer/reclaimer is handled by the field-proven Hydramation. With a simple and reliable hydraulic design, Hydramation delivers 0.125-in. precision for elevation, steering and cross slope. It is the only control system industry wide with a five-year warranty. Allega’s 4503s often work on projects with multiple lane widths. On the I-76 project, the crews worked the two trimmers in tandem and did not want to run main and intermediate lane stringlines for the trimming phase of the project. Therefore, Allega opted for a stringless way to precisely trim the material.
Both machines were equipped with the Trimble BladePro 3D. It provides automatic control of the trimmer’s elevation in three dimensions (XYZ). The system allows grading of complex designs such as vertical curves, transitions, superelevations and curves without stringlines. “We were able to get between 0.125- and 0.25-in. accuracy from the system,” Friess said.
Allega excavated between 4 and 8 in. of base and bedrock material with the two trimmer/reclaimers. Working in tandem, one 4503 cut at a 12-ft width, while the other trimmed a 16-ft grade. The two machines were also used to trim the stabilized sub-base.
The two Terex CMI 4503s delivered phenomenal results, allowing Allega to keep its concrete yield to within 3% and stone yield to within 5%. “These were the best yields that I have ever seen,” Friess acknowledged. “The trimmers allowed us to save up to 4% concrete yield of what was bid.” At $70 per yd of concrete, this yield savings added hundreds of thousands of dollars to Allega’s bottom line for the job. “I tell our customers that our trimmer/reclaimers pay for themselves through the yield savings,” Lampkin added.
300,000 Square Yards
During the 2006 paving season, Allega moved its equipment a few miles down the road to tackle an even larger reconstruction project on I-80. The three-year, $87.9 million project will require approximately 300,000 cu yd of concrete paving and 800,000 yd of dirt.
With work already under way, Friess said that this year the company will, once again, rely heavily on the trimmers to lower concrete and stone yields. With the positive results achieved on I-76, the 4503s should have no problem adding more profit to Allega’s bottom line.