This report summarizes findings of laboratory and construction evaluations of using residue from an atmospheric fluidized bed combustion (AFBC) process as a component in an experimental road base and subbase application. The base mixture contains pulverized fuel ash, AFBC residue, and limestone aggregates used as bulk filler. The subbase mixture contains AFBC residue and pond ash (ponded fly ash and bottom ash). Mixtures containing various proportions of each component were evaluated in the laboratory relative to maximum dry density, optimum moisture content, and compressive strength development.

Two 750-foot test sections of a 22-foot wide roadway, containing the experimental mixtures, were constructed in May and June 1988. Prior to construction, in-place California Bearing Ratio tests, moisture content determinations and Road Rater deflection tests were performed on the prepared subgrade. During construction of the experimental base and subbase layers, relative compaction and moisture contents of the materials were monitored by nuclear devices. Specimens were compacted for subsequent evaluations. Initial post-construction evaluations included compressive strength development, elastic modulus, Road Rater deflection analyses, and monitoring expansion of the experimental mixtures both in the field and in the laboratory.

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names are for identification purposes and are not to be considered as endorsements.