John Schert1, Dr. Timothy Townsend2, Dr. Chang-Yu Wu2
Hinkley Center for Solid and Hazardous Waste Management
2Department of Environmental Engineering Sciences

The objectives of this project were to identify potential concerns of using ammoniated fly ash in concrete and to provide recommendations for appropriate limits based on considerations of worker health and safety. A series of laboratory-scale exposure and leaching experiments with fly ash of different ammonium contents added into concrete were carried out to determine the mass transfer rates of ammonia/ammonium release from concrete to water/air. The measured mass transfer rates were applied in the semi-infinite diffusion model to assess maximum potential exposure for typical concrete handling scenarios. In overall consideration of modeling results, industry assessment, and results of previous research, a threshold of ammonium concentration in fly ash of 100 ppm was proposed for normal working conditions. However, the research team also recommended that appropriate safety protocols should be evaluated for some working conditions with poor ventilation.



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