Tag Archives: infrastructure

How self-healing concrete could fortify America’s crumbling roads

As Congress navigates another last-minute scramble to approve funding for the nation’s highways ahead of a July 31 deadline, engineers far-removed from the Capitol Hill gridlock are hard at work improving the stuff that sustains our nation’s roads and bridges: concrete.

Recent innovations point to stronger and higher-performing highways and bridges in the future. Some products are already on the market; others are a long way off.

It may sound far-fetched, but the technology exists for self-healing concrete. The auto-mending material contains limestone-producing bacteria that activates when wet. The bacteria can lie dormant for up to 200 years, according to the European Patent Office, where the technology is registered.

When a structure made of self-healing concrete develops a crack, water inevitably seeps in, prompting the bacteria to feed on calcium lactate in the concrete. The feeding process breaks down different minerals in the concrete and consumes oxygen from the air. This sets in place a process that converts the calcium lactate, which can be dissolved in water, to limestone, which fills the crack.

“This is kind of ‘The Jetsons’ stuff,” says Georgene Geary, with a laugh. Ms. Geary is principal engineer at GGfGA Engineering in Georgia, and chairs the Task Force on Nanotechnology-Based Concrete Materials at the Transportation Research Board in Washington.

“This is the future,” she says.

Hendrik Jonker, a microbiologist in the Netherlands who owns the patent to the technology, came up with the idea by considering how the human body repairs broken bones through mineral processes. The process for concrete works on a crack of any length, as long as it is no wider than 0.03 inches, according to the European Patent Office.

New technology also opens the door for self-cleaning concrete. Engineers such as Kimberly Kurtis, professor at the Georgia Institute of Technology in Atlanta, are studying ways to use light as a catalyst for cleaning the surface of concrete or binding pollutants in the surrounding air.

Ms. Kurtis’ team has examined the use of a special form of the mineral titanium dioxide, which has been manipulated to make the mineral react to light. When light hits the surface of a concrete structure containing this special type of titanium dioxide, it begins a chain of events that eventually destroys organic material on the surface of the concrete, such as bacteria. Moss and fungi that feed on bacteria are unable to grow without the food source.

“They can also interact with pollutants in the air – things like nitrogen oxides or volatile organic compounds – and bind those to surfaces to essentially clean the air,” Kurtis says.

Kurtis noted that the high cost of self-cleaning concretes make them best suited for smaller scale projects in particularly dirty environments, such as a section of wall facing a street with heavy pollution.

While self-cleaning concrete has been commercially available for the past decade, its use remains limited. Sculptures near the new Interstate 35 bridge across the Mississippi River in Minneapolis – built after the 2007 collapse of an earlier bridge  – use self-cleaning concrete, as does the Jubilee Church in Rome, a building celebrated for its stunning white walls and unique architecture.

If special concretes can kill bacteria, could they also purify water? Researchers at the University of Central Florida are working to develop a cleansing coating for concrete surfaces that will kill bacteria. According to Boo Hyun Nam, assistant professor of civil, environmental, and construction engineering, the idea is to cover the inside walls of pipelines and storage tanks with the coating to purify the water inside and prevent contamination. Mr. Nam would not specify what the coating is made of.

“It’s their secret recipe,” he says.


Published in conjunction with Arkansas Democrat-Gazette Logo

Lew and Foxx urge Congress to fund infrastructure

WASHINGTON — Treasury Secretary Jack Lew and Transportation Secretary Anthony Foxx called on Congress Monday to address the Highway Trust Fund shortfall before money runs out in little over a month’s time.

“It’s time for the country to take some bolda steps forward,” said Foxx, during a panel discussion at Bloomberg Government.

The federal government currently raises money for highway construction and transit programs through the Highway Trust Fund, which collects money from gasoline and diesel fuel taxes and is set to run out of money on May 31.

The gasoline tax and the diesel tax have been stuck at 18.4 cents per gallon and 24.4 cent per gallon, separately, since 1993.

“Businesses are wasting resources because our infrastructure is falling behind,” said Lew, who pointed out the U.S. was ranked 12th in global competitiveness by the World Economic Forum due to insufficient infrastructure investment.

“Look at the things we need to build a stronger future, infrastructure is right at the top of these,” Lew said.

The Transportation Department has unveiled a six-year Grow America Act plan that would spur infrastructure investment by raising the repatriation tax, but Republicans in Congress have not widely embraced the initiative.

“The best way to fund infrastructure for the long term is to tie it to something that is broadly popular,” said Lew. “That’s why we tie it to business tax reform.”

American multinational firms often keep overseas earnings abroad because they would otherwise have to pay as much as 40% in U.S taxes, according to KPMG, the accounting and tax firm.

In the administration’s proposal, firms would pay about 14% in repatriation, with proceeds from the tax going to fund domestic infrastructure projects.

“Democrats and Republicans in Congress want to have a long-term bill,” said lobbyist Cliff Madison, president of Government Relations, Inc. “However, they haven’t agreed on the sources for funding, whether it is going to be an increase on the gas tax or the repatriation of U.S. money from overseas.”

Foxx also said he is willing to listen to other solutions from Congress.


Published in conjunction with MarketWatch Logo