Solid-particle erosion of a geopolymer containing fly ash and blast-furnace slag

Solid-particle erosion studies were conducted on a geopolymer derived from fly ash and granulated blast-furnace slag. The erodent particles, 390 μm angular Al2O3, impacted at 30, 60, or 90° at a velocity of 50, 70, or 100 m/s. Steady-state erosion rates (ER) were obtained and the material-loss mechanisms were studied by scanning electron microscopy (SEM). The geopolymer responded to normal impact as a classically brittle material. Elastic–plastic indentation events led to formation of brittle lateral cracks that resulted in loss of material; erosion rate was proportional to erodent velocity to the 2.3 power. Impact at 60° produced similar results, with the erosion rates being in general slightly lower. Impact at 30° led to anomalously high erosion rates that were approximately independent of velocity. This response was attributed to presence of microcracks in the matrix and chipping of aggregates through propagation of radial cracks.