Date: Jan 29, 2017 Author: Ted Griggs Source: (
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A Louisiana startup believes a newly developed smart polymer will sharply reduce maintenance costs for concrete roads by adding years to the life of the sealants that prevent damage to the slabs.
Louisiana Multi-Functional Materials Group's two-way shape memory polymer behaves thermally opposite to concrete, said Chief Chemist Lu Lu. The polymer shrinks when heated and expands when cooled.
"Our design ... will solve the biggest problem of the concrete maintenance and installation job," Lu said.
In traditional concrete pavement, cuts in the slabs are made at regular intervals. This ensures that cracking occurs at the cuts, or joints. Sealants are placed inside to prevent water, rocks and other materials from getting into the joints.
Because concrete and the sealants expand during the summer, the sealant materials -- asphalt is commonly used because it's the cheapest -- often get squeezed out onto the road, Lu said. In the winter, both the concrete and sealants shrink, which can lead to gaps that allow water and rocks to get in.
When the slabs expand, the rocks can cause cracks. Water can corrode the steel rods inside the concrete that make it stronger. All those things lead to a less than uniform road surface, which can lead to potholes.
"That's why when you drive a car it's not a smooth ride," Lu said.
It's also why Louisiana and other states, as well as the federal government, need to spend lots of money each year on maintenance, Lu said.
For example, the Louisiana Department of Transportation and Development spends about $3 million a year on its preventive maintenance bridge program, which includes bridge joint rehabilitation, spokesman Rodney Mallett said. If the department had additional funds, more would be spent in all areas of bridge and road maintenance.
The U.S. Department of Transportation's Federal Highway Administration budgeted more than $3 billion during the 2015 fiscal year on restoration and rehabilitation work.
Louisiana Multi-Functional Materials Group's research showed the global market for sealants and adhesives used in the building, construction, automotive and transportation markets totaled $3.42 billion in 2014 and will grow to $5.68 billion by 2024.
The harsher the weather conditions, the more frequently the concrete slab sealants must be replaced and the cracks patched, Lu said.
The company's two-way shape memory polymer will contract and expand continuously, she said. The startup's up's goal is to create a material that lasts 10 years, can expand and contract by 30 percent to 70 percent and perform in temperatures ranging from minus 22 to 158 degrees.
The idea is to make something that can work anywhere in the United States, Lu said.
Although the polymer would be more expensive to install initially, maintenance costs would be much lower, and overall costs would be reduced, Lu said. That's because the sealant material isn't the biggest cost, the labor to install it is.
William F. Carroll Jr., an adjunct professor at Indiana University and a board member of the American Chemical Society, said it's difficult to estimate the size of the market for two-way shape memory polymers.
"These are not common materials. The reason they're remarkable is because they're counterintuitive," Carroll said. "Usually when you think about heating something up, you think about it expanding."
A balloon that's outside in cold weather gets bigger when it's brought inside into warmer temperatures, he said. These materials act the opposite of that, and the fact that the polymers are not common suggests the market for them isn't well-defined.
If Louisiana Multi-Functional Materials Group can get customers to use its polymer in building or repairing a lot of roads, the potential market could be large, Carroll said. But there are a number of factors still to be determined, such as how easily the polymer can be applied, how well it adheres to the road surface and the cost of the polymer.
Lu said the new polymer builds on earlier research that the company's founders have done in shape memory polymers. Li,a mechanical engineering professor at LSU, has 20 years of research experience in this area.
The startup recently received a $225,000 Phase I, Small Business Innovation Research grant from the National Science Foundation through the Louisiana Business & Technology Center at LSU. The Phase I grants are used to establish the technical merit, feasibility and commercial potential of the proposed research and to determine the grant recipients' quality of performance before providing more support through a Phase II grant, according to the National Science Foundation.
Louisiana Multi-Functional Materials plans to have the material synthesized, tested and tuned for real-road conditions by March or April, well before the Phase I grant period ends on Aug. 31, Lu said. By the end of May, Lu and the other company founders, Pengfei Zhang and Guoqiang Li, want to have test results in hand and begin writing their Phase II grant proposal.
Phase II grants are based in part on the Phase I results and the commercial potential of the products, according to the National Science Foundation. The Phase II grants are normally $1 million or less over two years.
The startup plans more real-road tests during Phase II, Lu said. Louisiana Multi-Functional Materials hopes to convince a construction company or DOTD to use the product commercially.
