Researcher creates concrete composite

When construction begins on the Southern Illinois Research Park's first new building this spring, a new kind of concrete developed at SIUC will help it take shape.

Concrete feat - Workers at the Egyptian Concrete Co. in Salem pour concrete made with bottom ash, a type of coal waste, into forms used in making temporary road barriers. SIUC researchers developed the experimental material, which performs as well as conventional concrete.

Bottom ash, part of the waste generated when power plants burn coal, will substitute for some or all of the sand used in conventional concrete. Contractors will use this new mix in the foundation and slab of the one-story, 19,920-square-foot facility as well as in surrounding curbs and their gutters and in sidewalks and driveways.

"This is a waste product that would otherwise go into landfills and ash ponds," said Sanjeev Kumar, SIUC associate professor of civil engineering who, with the help of his students, created the composite.

If, after seeing how well it works at the research park, the building trades adopt this new material, everyone comes out ahead. Construction companies could save as much as 10 percent on concrete costs. Utility companies would save big bucks by not having to pay landfill charges. And the environment would benefit from having one less product in the waste stream.

Right now, the research team is in the lab, tinkering with percentages of cement, sand, gravel, water and bottom ash needed to meet the design team's strength and stiffness specifications. In March, they'll build a test pad out at the construction site to make sure the mix works as it should and do some tweaking if it doesn't. Kumar expects construction to begin in spring.

While this is the first full-scale use of bottom ash in a construction project, Kumar and his team have been working on ways to make it into a building material for about five years. They began with a series of laboratory experiments designed to test concrete made with different amounts of the stuff for strength, stiffness and durability.

Encouraged by the results, the researchers next tried out their altered concrete by building make-believe foundations at the Illinois Coal Development Park in Carterville and testing them under field-loading conditions.

"The performance of the concrete composites was almost as good as and in some cases better than the equivalent conventional concrete, " Kumar said.

Last summer, the Illinois Department of Transportation agreed to give the SIUC concrete composite a whirl in constructing the temporary road barriers used to divert traffic during road repairs.

"We'll know more with the passage of time, but the performance we have seen so far is similar to that of the barriers made with equivalent conventional concrete," Kumar said.

"The work with IDOT lets us test under real-world conditions. This current project (at the research park)takes us a step further because we're using these composites on an actual building."

-- K.C. Jaehnig