Flawed concrete found on Detroit Metro Airport runway

Editor's note: A previous version of this story incorrectly indicated that deicing chemicals can cause alkali/silica reaction. This version is correct.

The $225-million runway that Detroit Metro Airport added in 2001 was expected to last for 30 years, but cracks and flaws in the concrete that started to show just three years after it opened have posed risks to safety and are forcing a costly reconstruction.

It's just one example of an epidemic of road and other projects with weak concrete failing before its time in Michigan and across the country, posing safety issues on roads and at some airports.

The potential danger from deteriorating concrete is clear, especially on runways, said airport spokesman Michael Conway.

"You don't want any foreign object debris on a runway because foreign object debris can get sucked into jet engines," he said. "We're out there repairing a lot just to make sure that we have a smooth surface and nothing loose floating around out there."

Metro Airport officials say they've stayed ahead of the problem with constant patching but that a larger more permanent fix is now needed.

Airports in Colorado and Nebraska have experienced similar runway issues with the problem known as alkali/silica reaction, or ASR, which causes concrete to expand and crack when exposed to moisture over time. An unknown number of road projects in Michigan and elsewhere in the nation also are affected, according to studies.

The economic toll is unknown, though it appears to be a vastly expensive problem. For taxpayers, the added expense comes from having to patch and rebuild roads, including sections of 8 Mile, Big Beaver and Utica roads. Cars also can experience damage from crumbling roads because of the weaker concrete.

Metro Airport — in the early stages of planning the runway's reconstruction — is applying for a federal grant to pay for part of the cost. The exact price tag is not yet known, but it should come in much cheaper than the original cost because it's not a wholesale replacement, said Jeffrey Warkoski, the Denver-based consultant working on the project. Similar repairs at Denver International Airport have cost $10 million to $30 million per runway, Denver Airport officials told the Free Press in an e-mail.

Road damage from the problem has been widespread in southeast Michigan, according to a 2006 study sponsored by the Michigan Concrete Paving Association. The study found ASR in all 23 core samples taken frmom 12 roads in Wayne, Oakland and Macomb counties. That study noted "issues of concrete durability have arisen with some of the pavements built after 1990."

Daniel DeGraaf, executive director and chief executive officer of the Michigan Concrete Association, said, "We have some projects ... that are not performing like they're supposed to do. ... It's not our proudest moment."

A widespread problem

Experts agree on how ASR forms, but there doesn't seem to be a consensus on why it has been such a major problem in recent years. There have been multiple theories, including new cement manufacturing standards because of new environmental standards, substandard sand used as mixer and widespread use of winter deicers on runways and roads.

The Federal Highway Administration said in one its fact sheets that ASR is a widespread problem and major cause of "concrete deterioration" in the lower 48 states and in other countries.

Fixing the problem after the fact has proved difficult, the industry says.

ASR develops when the crushed stone, sand or other materials that make up concrete react with cement paste that has a high level of alkalinity when moisture is present. The reaction produces a gel, which swells and expands the concrete, leading to cracking and other damage. That damage is compounded as more areas are opened to moisture.

A common way to reduce the alkalinity in the cement is to add fly ash, a byproduct of burning coal. The fly ash "also densitizes the mix so there's less chance for water to get into it," DeGraaf said. "We kind of waterproof the concrete by using the fly ash."

ASR is not a new phenomenon. The issue was first chronicled by Thomas Stanton of the California State Division of Highways in 1940, according to the FHA fact book, which noted that it was later "diagnosed as the cause of abnormal cracking in a number of dams operated by the U.S. Bureau of Reclamation."

ASR also has been blamed as the cause of runway problems at other airports, including at Denver International, which was mentioned by numerous experts the Free Press interviewed.

An airport official at Denver International, which has problems with three runways, said that "pavement rehabilitation" projects can cost $10 million to $30 million for each runway complex. Two runways have already been rehabilitated, and work on a third is scheduled for 2015.

Denver airport, which opened in 1995, has had other issues with its concrete. The paving contractor, a now-defunct California company, was accused of trying to save on cement costs by mixing in extra sand and gravel, according to a 2006 Rocky Mountain News article. The company agreed to pay $430,000 to dismiss a civil complaint and cover whistle-blower attorney fees associated with the work at the airport and at the John Wayne Airport in Santa Ana, Calif., according to a 2000 report to Congress by the Office of Inspector General of the U.S Department of Transportation.

Changes in cement mix

The Michigan Department of Transportation suggests that changes over the past three decades in manufacturing concrete contributed to the problems, especially in the way cement is mixed, the key binding agent in concrete.

"The cement manufacturing industry has increasingly been under pressure to reduce their levels of harmful emissions into the atmosphere," according to an e-mail from MDOT spokesman Jeff Cranson. "This prompted them to modify their manufacturing process to incorporate a portion of the highly alkaline cement kiln dust back into their final product."

DeGraaf, of the Michigan Concrete Association, noted that when concrete and other materials are modified, even when the intent is to improve them, they can change in unexpected ways.

Larry Sutter, director of MDOT's Transportation Materials Research Center at Michigan Technological University in Houghton, where he is also a professor, said manufacturing changes to make the environment cleaner do not come without a cost, but he cautioned that those changes would represent only one part of the equation.

"There's no one overwhelming factor that causes pavement deterioration," he said.

Testing and inspections

Sutter said he believes ASR is less of a problem than inadequate funding for road maintenance in Michigan and the damage caused by freezing and thawing of pavement.

He said transportation agency policies demanded by the traveling public to keep roads cleared add to the problem because the methods used to clear ice and snow can keep roads saturated with moisture.

He disagreed that ASR damage is as widespread as the 2006 study on southeast Michigan roads suggests, noting that there are thousands of road miles that are "pristine."

Others acknowledge ASR is a significant issue but insist methods to preemptively test for it, along with certification and inspection programs through agencies such as MDOT, ensure the problem can now be managed.

"Presumably ASR has always been an issue … but it hadn't been tracked to the extent it has been in the last 30 years or so," said Warkoski of Denver-based RS&H, the firm handling the preliminary design of the Metro runway project. He noted that road and other agencies began tracking the phenomenon when they realized they were spending more money than they thought they should on fixing problems from weak cement.

Experts insisted that ASR's emergence in the last couple of decades was a surprise.

"When this stuff started popping up in the early 2000s, people were ready to slit their wrists and jump off cliffs," said DeGraaf, who noted that it was "baffling" because those involved in the concrete industry were essentially operating as they had been before.

Still, he suggested that some sand used in concrete at the time probably should not have been used for anything other than backfill, but before ASR garnered renewed attention in the 2000s, there was no way to know.

The 2006 study was a direct reaction to the situation. Additional research led to the development of tests and guidelines that now inform the industry, helping ferret out problem concrete before it is used in projects, DeGraaf said.

"We test our mixes now and actually prove that they work before they're used in these projects," DeGraaf said. "We are very, very confident that we're making good material that will not be subject to the same kind of a problem in the future."

Is there a warranty?

Conway acknowledged that the runway replacement is a big project, in part because of the quantity of material in a runway, which in nearly 3¹/₂ feet thick. The structure is built in three layers — 17 inches of concrete, 9 inches of asphalt and 16 inches of crushed stone.

When asked whether a warranty would cover any of the replacement or whether legal action is possible to recover any costs, Conway replied that "the Airport Authority continues to review and analyze the issue," but he noted that "our current understanding is the concrete was installed in accordance with the project specifications."

The contractor on the original project is listed as "Dan's Excavating, Inc./Ajax Paving Industries, Inc. a joint venture."

A person who declined to give his name but called himself a representative of Dan's Excavating said during a phone call that Dan's is the contractor of record on the project. But he said his company does not handle the concrete and said the project is 14 years old (the runway actually opened just more than 13 years ago). He declined further comment.

Officials at Ajax Paving in Troy did not return calls seeking comment.

The rapid deterioration of the runway stands in contrast to a runway at Willow Run Airport, which is also operated by the Wayne County Airport Authority. That runway reopened in October at Willow Run after a $45-million reconstruction of the 75-year-old runway that was originally built to launch B24 bombers, according to the airport authority.

That runway, which had been repaired many times and did not experience the same volume of heavy traffic as the Metro Airport runway, was installed by Henry Ford.

Safety concerns

Warkoski said concrete with ASR eventually fails, but before that, the top layer sheers off, and small chunks come loose, a particular safety hazard at airports.

ASR was confirmed in some core samples taken from the runway.

The process to rebuild Runway 4L-22R, one of four parallel runways and among six at Metro, is just beginning. Officials held an open house in November for the public to learn about the project, although Conway says only two members of the public attended.

There is no cost estimate for the new runway, but Warkoski said he expects it to cost less, adjusted for inflation, than the original 10,000-foot-long runway because the work would be a replacement of an existing structure. Conway said the Airport Authority intends to apply for a Federal Aviation Administration grant and fund the remainder through general airport revenue bonds.

The exact time frame for construction is unclear — the FAA needs to weigh in, for instance — but airport officials would like to begin in 2016 and complete the project in 180 days in order to minimize disruptions.

"Basically, what we're doing is building a runway right on top of an existing runway," Conway said. "We're not lengthening it, we're not shortening it, we're not moving it, we're rebuilding it in place."

Contact Eric D. Lawrence: elawrence@freepress.com. Follow him on Twitter: @_ericdlawrence

Concrete or cement?

"Concrete is basically a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and cement. ... Cement is manufactured by heating lime, silica, alumina, iron and other materials at high temperature. The resulting substance is a marble-like ball called clinker that is ground, mixed with limestone and gypsum, and used to create concrete."

Source: Portland Cement Association (Portland is a generic term for cement)