Iroquois County
June, 2008

Challenge

The existing 3.5 miles of 14-foot oil and chip surface had a minimal aggregate base and was insufficient width for vehicle to pass without pulling onto shoulder. The strength of the road was insufficient for regular traffic and truck traffic from a nearby gravel pit.

County budget constraints and keeping the road open to local traffic added to the complexity.

Solution

A cross section of the road was widened to allow addition of three lanes of pavement on either side of the existing roadway. (This was completed by county work force in fall 2007).

Four inches of crushed aggregate was added on either side of the existing roadway after ditches were relocated. (This was completed by county work force in fall 2007).

Pulverized and blended aggregate material was added to the existing oil and chip surface. The blended material was stabilized with 10 percent fly ash to a depth of 12 inches and width of 20 feet.

The road was graded and compacted and a bitumenous cure coat applied. The roadway was trimmed with a full lane rotomill using a 30-foot averaging ski with a 2 percent cross slope was established. The material from trimming was placed as aggregate shoulders. An A-2 bituminous surface treatment was applied.

Construction Phasing

Phase 1: Pulverize and blend existing oil and chip with added base materials—2 days

Phase 2: Incorporate fly ash, grade and compact—3 days

Phase 3: Curing—7 days

Phase 4: Apply A-2 surface treatment—2 days

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