ForConstructionPros.com

Much of the almost two million miles of asphalt roadways in the United States are severely distressed and in need of repair or replacement. Over the last few decades increasing traffic demands combined with decreasing funding for repairs, environmental concerns and an emphasis on safe, efficient, transportation systems have stimulated research and field demonstration projects to explore methods to reuse and recycle pavement materials.

In response to this need, the Department of Civil and Environmental Engineering and Geodetic Science at Ohio State University (OSU) has partnered with the two fastest growing counties in Ohio (Delaware and Warren) to construct and monitor two pavement sections in which sections of failing asphalt pavements were recycled in 2006 using Ohio coal-generated fly ash as a cementing agent.

"The value of this technology and demonstration project to the contractor is at a minimum two-fold," says Chris Anspaugh, construction manager, Base Construction. "With the price of cementitious additives continuing to rise in price due to the substantial energy costs involved in producing them it would be of value to the contractor, from a competitive standpoint, to have alternative products available that will achieve the same end results.

"Secondly, the contractor needs testing data available that can be submitted to the owner to assure them that the product will perform as we are claiming," he continues. "This research will go a long way in providing that information." and lime-activated Class F fly ash

On this Full Depth Reclamation (FDR) research preservation project, the complete depth of the flexible pavement section consisting of the asphalt layer, base, subbase and a pre-determined amount of the underlying existing subgrade soil were uniformly pulverized, blended with chemical additives (Class F fly ash in combination with lime or lime kiln dust), and compacted to construct a new stabilized base course.