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Issue link: http://airportbusiness.epubxp.com/i/813534
RUNWAY REPAIRS April 2017 airportbusiness 15 (FHWA) said in one of its fact sheets that ASR is a widespread problem and major cause of concrete deterioration in the lower 48 states and in other countries. ASR happens when the crushed stone, sand or other materials that make up concrete react with cement paste that has a high level of alka- linity, when moisture is present. The reaction produces a gel, which swells and expands the concrete, leading to cracking and other dam- age. That damage is compounded as more areas are opened to moisture. After years of maintenance on the runway, the Wayne County Airport Authority decided it was necessary for a partial runway recon- struction of Runway 4L/22R and associated taxiways. The project called for replacement of the top layer of concrete and a small portion of HMA base under the concrete. The nearly 3½-foot thick structure is built in three layers — 17 inches of concrete, 9 inches of asphalt and 16 inches of crushed stone. The runway is substantial because it is 10,000 feet long and it is where the jumbo jets, such as the Boeing 747 wide-body commercial jet airliner and cargo aircraft land. The airport authority had allotted a tight 180-day schedule in order to minimize the dis- ruption. DTW is a major international airport in the U.S. and one of the largest air transpor- tation hubs in the country. In terms of aircraft operations Detroit Metro is one of the 10 busiest airfields in North America. Runway 4L-22R is one of four parallel runways and among six total runways at Detroit Metro. To say the Wayne County Airport Authority was nervous about taking a major runway out of service for six months would probably be an understatement. The complete runway reconstruction project included the asphalt shoulders and Taxiways A and Q. The reconstruction of the associat- ed taxiway system is designed to provide a safe connection for aircraft from the runway to the passenger terminals at the Detroit Metro Airport. In total, the project encompasses 6.5 miles of airfield pavement. "Basically, what we're doing is building a runway on the same footprint as the existing runway," said DTW spokesperson Michael Conway. "We're not lengthening it, we're not shortening it, we're not moving it, we're rebuild- ing it in place." Ajax Paving Industries Inc., of Troy, Mich.