FDOT Testing and Evaluation of a Beneficial Re-Use Base Course Material

The beneficial re-use of by-products produced from the combustion of solid fuels has gained momentum with the growing interest in "Green" initiatives in construction. However, modern environmental controls and the simultaneous tightening of construction material approval specifications continue to provide technical challenges to implementation. Traditional construction markets for ash have now been refined to the point where many by-products may be excluded due to elevated levels of sulfur and other potentially reactive elements. A number of case studies have recently been demonstrated by JEA, in Jacksonville, Florida with the use of hydrated ash from Circulating Fluidized Bed (CFB) boilers in pavement construction applications. A `green" pavement base product consisting of a blend of this hydrated CFB by-product with conventional construction aggregates has been demonstrated to provide excellent performance when compared with traditional Florida base materials. The Florida Department of Transportation (FDOT) has conducted extensive laboratory, large-scale test-pit, and full-scale field testing on this material. The detailed test program conducted by FDOT and the preliminary results of such are documented in this paper.