Intelligent Compactor Exceeds Expectations

Colorado is a state that covers more than 100,000 square miles of land, much larger than England and many other European Countries. Yet, only two major interstates dissect this large state – I-70 from east to west and I-25 from north to south. The state’s only other major artery, I-26, enters the state from the northeast but ends in Denver.

There are only a few thousand lane-miles of interstate, reaching predominantly the northern and eastern territories, for Colorado’s roughly 4.5 million citizens. When sections of these multi-lane expressways are closed, as were the I-70 westbound lanes for several days in August due to rock slides, traffic is left to find alternate routes to get from point A to point B.

Many of Colorado’s drivers rely on its vast network of two-lane highways, winding throughout the Rocky Mountains. These roads are the only means to get to small, out-of-the-way towns like Gunnison and Ouray. In order to move commercial and commuter traffic safely, these roadways must be well maintained.

Deteriorating highway

This is exactly why a 24-mile stretch of Highways 141 and 145 in southwest Colorado is receiving some much needed upgrades. Performing this work is the United Companies, a division of Old Castle, based in Grand Junction, CO. The sand and gravel, ready mix concrete and asphalt contractor is charged with paving 48 lane-miles of Highways 141 and 145 with a fresh two-inch overlay of asphalt. The project required nearly 50,000 tons of a SX75 mix with a 1/2-inch top aggregate size and PG58-28 binder.

Some of the more deteriorated sections of Highway 145 around the city of Norwood were treated with a hot-in-place recycling method in order to increase the new mat’s longevity. “Through this process we are improving the road’s old surface and eliminating the chance for any reflective cracking to show through the overlay,” says Ken Dobey, paving superintendent for United.

Mixed by United’s portable asphalt plant strategically located in the middle of the 24-mile project, the hot asphalt was delivered to the paving train by 10 belly-dump trucks and laid in a windrow. “There is a shortage of trucks in western Colorado, and the belly-dumps reduce the number of trucks we need to deliver the asphalt,” says Dobey. “We would need 20 to 25 tandem axles to keep the same production.”

The windrows offer the side benefit of allowing the paving crew to develop a continuous paving process, so they can lay a higher quality mat. It helps United to achieve the density and smoothness specs required by the end-result contract.

Smoothness requirements fell under the Colorado Department of Transportation (CDOT) Category 2 standards of 8-16 inches per mile. The tough density specs demanded that the contractor achieve 93 to 96 percent compaction across the mat and 88 to 92 percent at the joints. To aid in achieving these specifications, United rented a new “smarter” roller that has the power and intelligence to quickly meet density specs without over-compacting.