Discussion of "Geotechnical Properties of Fly and Bottom Ash Mixtures for Use in Highway Embankments" by Bumjoo Kim, Monica Prezzi, and Rodrigo Salgado.

The authors talk about a study involving the compaction, hydraulic conductivity, and one-dimensional and drained triaxial compression tests of fly- and bottom-ash mixtures. They comment on research on high-pressure isotropic compression tests performed on burning coal ash specimens obtained from a thermal power station in Charqueadas in southern Brazil. They state that the Unified Soil Classification System rates Charqueadas coal ash to be a nonplastic silty sand. They comment that Charqueadas ash has a high internal porosity of the grains and that the particles are more crushable. They mention that leaching tests have been performed on fly ash and found they were potentially hazardous because of heavy metal contaminants.