Technology for using sulfate waste in highway construction. Final report

Mixtures of fly ash, lime and sulfate waste were examined for their potential use in highway construction. During this initial phase of the project, variables such as fly ash source, form of calcium sulfate, lime type, mixture consistency, curing temperature, admixtures and impurities expected in waste sulfates were examined. Also, studies of compound development in selected mixtures were performed. The second phase of the study was designed to obtain strength-compositional relationships for samples prepared with actual waste sulfates. These waste sulfates included neutralized acid mine drainage, titangypsum, hydrofluoric acid by-product, gas scrubber waste and neutralized steel pickling liquor. Results of this phase were used for the selection of mixtures for engineering evaluation. These mixtures were examined for compressive and tensile strength, freeze/thaw resistance, wet/dry stability, California bearing ratio, permeability and leachability.