|
WEST LAFAYETTE, Ind. - Civil engineers at Purdue University and the Indiana Department of Transportation are teaming up on green projects around the state, including work aimed at saving taxpayers $300,000 annually by recycling a waste product from cement manufacturing.
As waste sources are further developed, cement kiln dust could be used to replace 70 percent of the roughly 1 million tons of lime used on projects annually to strengthen soil so that it can support new pavement.
"This represents a significant amount of potential savings for INDOT and may actually be higher," said Barry Partridge, research program director of INDOT's Joint Transportation Research Program. "Based on 2002 production rates, Indiana cement plants conservatively generated about 30,000 tons of cement kiln dust each year. At cost savings of $10 per ton, this generates annual savings of at least $300,000."
Marika Santagata, an associate professor of civil engineering, worked with Partridge and other state transportation officials including Nayyar Zia Siddiki, supervisor of geotechnical operations at INDOT. Early work was aimed at evaluating possible reuse applications for cement kiln dust.
A test section with cement kiln dust was used for repairs to Pendleton Pike at Interstate 465 in Indianapolis in 2008, along with a traditional lime-modified section. The kiln dust showed comparable engineering results at lower cost. Cement kiln dust is being used this year on the U.S. Route 24 "Fort to Port" project east of Fort Wayne.
Research conducted in Santagata's Purdue lab focused on testing cement kiln dust for strength and durability following standards established by the American Society of Testing Materials. The kiln dust was provided by an Indiana cement plant.
The work, conducted through the Purdue-based, INDOT-funded Joint Transportation Research Program, or JTRP, yielded promising results, Santagata said.
"Recycling cement kiln dust and other waste products for highway projects represents a huge untapped green resource," said Santagata, who had several students working on the project. "Cement kiln dust is cheaper and, provided that the chosen source has appropriate chemical and physical properties, can perform just as well as the other materials in soil modification and stabilization."
An economic analysis prepared by JTRP research scientist Bobby McCullouch shows the cost-benefit ratio is 52-to-1, meaning that for every dollar spent on the research the state could realize a return on investment of $52 over a 20-year period.
In practice, INDOT was able to save $90,000 from the use of cement kiln dust on the initial U.S. 24 contract. On a second U.S. 24 contract, INDOT realized a savings of $332,000 when the unit price was reduced by half, from $4 to $2 per square yard. The Fort to Port project, scheduled to open to traffic in late 2012, involves building a four-lane, limited-access highway from I-469 to the Ohio state line.
The research led by Santagata and Siddiki also provided input for new specifications and design procedures for contractors to follow when using cement byproducts. The new specifications will allow the use of cement kiln dust on future INDOT soil modification projects, Partridge said.
The specifications, which will be published in the INDOT Standard Specifications, detail material selection, testing and storage of the cement kiln dust.
"Once the state has specifications in place, cities and counties and towns will likely use cement kiln dust as well," Partridge said. "So the specifications open up that opportunity and market."
Two other states, Michigan and Oklahoma, also have experimented with the cement kiln dust on highway projects. Nationwide, more than 4 million tons of kiln dust from cement manufacturing is available as a lime substitute.
The material is especially cost-effective for contractors near Fort Wayne and in northwest Indiana because it is produced by manufactures in those regions, reducing shipping costs.
Efforts to recycle cement kiln dust dovetail with other INDOT green projects involving Purdue civil engineers, including work to recycle steel slag and fly ash in constructing a new interchange at 109th Street and Interstate 65 in Crown Point; recycling shredded tires to prevent landslides; recycling foundry sand and crushed glass as fill materials for projects; and recycling coal ash from Indiana power plants, 300,000 tons of which was used as embankment fill on the State Route 641 Terre Haute bypass.
Received from Purdue University News Service,
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
|
Indianapolis — A company that recycles expanded polystyrene has a drop-off site that’s open to the public. Createc of Indianapolis densifies the product and sends it to reprocessing plants, which convert it to crystalline polystyrene to be used again by plastics molders. Until recently, expanded polystyrene (Styrofoam is the most familiar trademark) has been the hardest item to recycle. Clean, white EPS, No. 6 plastic can be deposited in bins on the southside of the Createc building, 6835 N. Guion Road, 8:30 a.m. to 4:30 p.m., Monday through Friday.
