Pothole-Proof Roads: Making pavement last - Part 1


SOUTH BEND, Ind.--- For our area this will go in the record books as arguably the 4th worst winter in recorded history, and potholes were what was left behind.

One of the three Super Pave Research sites in the country is in West Lafayette where INDOT and Purdue University work together to try and make our roads better.

Researchers at Super Pave use machines to simulate seven years of interstate traffic in one week. These machines can heat asphalt up to 120 degrees, the hottest point of the year.

Since 1995 the "Super Pave Center" has been testing different asphalt mixtures to see which ones hold up the best. The research has allowed many changes to be made as a means of improving the asphalt used on our roads all across the Midwest.

“One of the biggest areas is in cracking of a pavement,” said Rebecca McDaniel, of the North Central Super Pave Center at Purdue. “By selecting the right asphalt, the glue that holds the pavement together, we can make sure that pavement won't crack, or at least it won't crack because of changes in temperature.”

McDaniel says that one of the weakest points of any road is at the seams where the paving machines lay down the road, and a recently finished study here has shown ways of helping that problem.

“INDOT has implemented a technique where after the pavement is constructed they put a sealer in that area to prevent the intrusion of water and air, and improve the joint performance,” said McDaniel.

At Purdue University, associate professor John Haddock, has been studying asphalt for 25 years. Along with his research, one of the many classes he teaches is pavement design.

“I always tell the students, look, if you really want a pavement to last you have to pay attention to three things and its drainage, drainage, drainage,” said Haddock. “You must get the water out and away from the pavement because water will just destroy it.”

The trouble with constructing roads in Michiana is that we get water, rain and snow all the time. That's along with extreme cold and extreme heat; a tough combination for any road.

“They use very dense hot mix on the sub grade to stop water from moving up, and they have an open-graded layer in there, meaning it has a lot of voids so that any water that gets in there is immediately run out the side into the edge drains,” said Haddock.

So air pockets are important. In just the right amount, they allow good drainage when the temperature is mild; however, not much works when temperatures plunge well below freezing. The water turns to ice and expands cracking the asphalt.

Researchers are now looking for ways to keep this to a minimum.

INDOT finished a project last summer in Elkhart County where they are trying a new pavement that has less air pockets, but still enough to allow for expansion and drainage.

“We would probably recommend trying it in the six districts next year and if they perform the way we think they will perform we can design all of our mixes this way,” said McDaniel.

And as far as fixing pot holes today, and in the immediate future, some proper techniques need to be applied.

But the problem, like we saw late this winter, is there are so many to get to all at one time.

Today was the first day that crews started hot patching potholes, which are a more permanent fix, so things are improving, but potholes will always be with us around here.

What Purdue and INDOT want to do is lengthen the time that a road lasts in the future.

That not only saves taxpayers money, but saves some of our rims and tires as well.


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