Enhancing the chemical performance of phosphogypsum as a road base material by blending with common aggregates

Interest in reuse of phosphogypsum (PG) road base materials has resurged as alterative disposal to stacking, but is limited due to regulatory constraints surrounding chemical composition and mobility. Prior to implementation of a waste product, direct exposure and leaching-to-groundwater risk should be determined, however the chemical behavior of PG blended with other base materials has not been thoroughly investigated. The total and leachable concentrations of trace metals, anions, and radionuclides from several PG sources, common base aggregates, and PG-aggregate blends were assessed. Between PG samples, older PG leach lower As, Sr, Mo, and fluoride than newer from the same facility. Blending PG with aggregates reduced total and leachable concentrations of interest for at least one blend, attributed to decreased PG content, change in pH, or addition of binding minerals. Blending PG with limerock or recycled concrete aggregate reduces direct exposure and leaching-to groundwater risk, expanding opportunities for PG reuse.