Real densities (ρreal) of CSP and HS pellets were measured by He gas pycnometer (Micromeritics Accupyc II 1340),using an equilibration pressure of 0.0050 psig min−1 for high precision measurements. Bulk densities (ρbulk) were obtained by the Archimedes method, using ethanol as the liquid medium. The mass of the as-produced sample (md) was first measured. Then the sample was immersed in ethanol for 2 min to fill open pores with the fluid, prior to measuring the mass of thesample in the liquid medium (ml). The sample surface was then gently wiped to remove any excess on the surface and the mass of the sample saturated with liquid (ms) was measured in air.