A University of Texas at Arlington civil engineering team recently installed a new mix of lime and fly ash on a section of U.S. 82 as a base to reduce soil sulfate heaving and extend the life of the highway as part of a new Texas Department of Transportation field implementation project.
Anand Puppala, distinguished teaching professor in the Civil Engineering Department and associate dean for research in the College of Engineering, is leading the project, which was installed on part of U.S. 82 near Bells, just east of Sherman. Puppala's post-doctoral student Aravind Pedarla is leading the field research for this two-year $150,000 project. Doctoral candidate Ahmed Gaily is assisting in the fieldwork.
Khosrow Behbehani, dean of the College of Engineering, said the work Puppala is doing for TxDOT could increase the longevity of the state's roads and reduce their deterioration.
"It's an applied project that not only improves the maintenance of Texas' roads but, also it helps motorists' vehicles, since better roads equates to greater longevity of vehicles," Behbehani said.
Much of Texas' soil includes high levels of sulfate or gypsum, Puppala said. The soil when treated with lime or cement will heave or swell under the extreme variance in moisture and temperature and this tends to cause the roads to crack.
"That change in moisture buckles the road," said Puppala, who has had successful results in using the similar mixture of lime in soil at Texas dams that experienced similar heaving. "This mixture greatly slows down the heaving cycle."
Puppala secured a $500,000 grant in 2010 from the U.S. Army Corps of Engineers to study and shore up cracks in Texas dam soil and this project will end in September 2015.
Adding more lime and fly ash, which is a coal power plant product, and allowing that mixture to mellow or age adds to the stability of the road, he said.
The current project tests the lime and fly ash mixture on three strips of U.S. 82. One strip was treated with the new mix of lime and fly ash. The second strip was treated with lime and extended mellowing. The third strip was the control strip.
Soil mellowing introduces cycled wetting and drying to loosen large clods or a compacted layer in the base.
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