Table 2.

The formulas for particle size parameters.

Particle size parameters	Formula
Median particle size (Mz)	Mz = Ф50
Average particle size (Md)	Md = (Ф16 + Ф50 + Ф84)/3
Standard deviation (σ)	σ = (Ф84 − Ф16)/4 + (Ф95 − Ф5)/6.6
Skewness (SK)	SK = (Ф84 + Ф16 − 2Ф50)/2(Ф84 − Ф16) + (Ф95 + Ф5 − 2Ф50)/2(Ф95 − Ф5)
Kurtosis (KG)	KG = (Ф95 − Ф5)/2.44(Ф75 − Ф25)

Φ = − log 2 D, D is the particle size of the particle, unit: mm.