Beneficiation of stockpiled fluidized bed coal ash in road base course construction

The presented paper investigates the potential for the utilization of unprocessed, as excavated (i.e. unground), stockpiled coal combustion fluidized bed ash in road base course construction. In addition to functioning as a stabilizer of the fines in the stockpiled material, this ash also permits treating the stockpiled ash agglomerates as an aggregate. Both untreated and cement-treated mix designs were evaluated. The laboratory program included unconfined strength measurements, triaxial, volumetric swell, and moisture susceptibility testing protocols performed on cylindrical specimens compacted at their optimum moisture content. The results have shown that, without breaking down the agglomerates by grinding, the unstabilized stockpiled ash possesses very little residual cementitious activity; whereas, if treated with small amounts of cement (3%), it meets the required strength criteria for cement-treated base courses while minimizing the volumetric swell characteristics. (C) 2010 Elsevier Ltd. All rights reserved.