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Every contractor who owns construction machinery knows it's important to generate as many profitable hours as possible out of any given piece of equipment. So when Lindsey Contractors Inc. of Waco, TX needed to pulverize a stretch of a county road, they decided to use their Roadtec RX-900 cold planer instead of a traditional reclaimer/stabilizer.

The job consisted of 1.5 miles of an old chip seal road just south of Dallas. The road was 24 feet wide, and covered with 4.5 inches of flex base (aggregate) and three different layers of ½-inch chip seal from previous preservation efforts. Lindsey Contractors was looking to use their RX-900 cold planer to pulverize the 1.5-inch layer of the chip seal and work it into the flex base all in one operation. Two simple changes from the regular milling mode were made and the crew was ready to get some profit-generating hours out of the RX-900 that did not involve traditional milling: the front-loading conveyors were turned off and the rear cutter housing door was opened to leave the processed road material on the ground.

Executing the job

Lindsey's milling crew had to experiment with the cold planer to find out how to produce the best gradated material to achieve the desired compaction results.

First, the crew ran the machine in both directions to check the gradation results. The gradation of milled material will be different, depending on whether the drum is up-cutting or down-cutting. The up-cut material graded evenly from dust on top to two inches on the bottom. The down-cut method placed the larger material on top. In this case, the crew liked the gradation achieved when up-cutting. Roadtec's Terry Leber, who was observing the work, says that "as you dug down in the windrow, the material got coarser as you dug deeper." Then the crew adjusted the rear cutter housing door to spread, or screed, the material in the cut.

The machine traveled in the forward direction exactly as if they were cold milling with the conveyors turned off. The rear cutter housing door was opened just enough so that the pulverized material stayed on the ground, and the size of the opening was set to let the material flow under the door and to screed the windrow flat.