Coal Flyash Tested As Building Block Material

Researchers at ORNL’s Buildings Technology Center, working with TVA and Babb International of Ringgold, Ga., are testing an autoclaved aerated concrete block weighing as little as one-fifth the weight of an ordinary concrete block. This block is composed of 70 percent recycled flyash produced by TVA’s coal-fired power plants.

Babb International is the largest U.S. manufacturer of autoclaved aerated concrete products.

Plans call for the flyash block wall to be tested for one year at a Habitat for Humanity home to be built in northern Georgia. ORNL researchers hope to install instrumentation while monitoring the energy efficiency and air-tightness of the home. The results will be compared to data obtained from the insulation monitoring of two Habitat homes built more than a year ago in Lenoir City.

Jeff Christian, director of ORNL’s Buildings Technology Center, said that energy production and energy efficiency both can benefit through this project.

"One of the unique aspects of this particular research project is that it helps the supply of energy by utilizing historic waste stream – being flyash from coal-fired power plants – and enhances the country’s efforts to improve energy efficiency by providing an energy efficient construction material," Christian said.

The project will help the Department of Energy reach both of the broad goals underlying the most recent national energy plan – providing energy supply in an environmentally responsible manner and promoting energy conservation.

Testing is taking place at ORNL’s Buildings Technology Center, a DOE national user facility that is the site for conducting research in improving systems that make up roofs, walls and building foundations, as well as the insulating materials these systems contain.

Christian said preliminary tests in the Buildings Technology Center’s whole-wall hot box indicate the walls produce a thermal mass effect that can heat a home at night long after the sun has set.

"The thermal mass benefits of the autoclaved aerated concrete wall can result in a home as energy efficient as a typical home constructed of 2 by 4s in the Knoxville area," Christian said.

This wall test marks the 200th user of the facility, which has provided whole-wall performance evaluations of 67 different wall systems for industry users.

ORNL is a multiprogram science and technology laboratory managed by UT-Battelle for the Department of Energy.