31.2.3. Particle size distribution
To determine the particle size of calcium sources, a set of sieves (Endocott, London, UK) sized 2, 1, 0.5, 0.212, 0.106and 0.075 and a sieve shaker were used as described by Baker and Herman (2002). The samples were passed through thesieve stack on shakers for 10 min. The amount of sample retained on each sieve was determined and, the geometric meandiameter (GMD) and geometric standard deviation (GSD) were calculated for each sample. These calculations were basedon the assumption that the weight distribution of the samples is logarithmically normal.