granulometry

Granulometry is the measurement of the size distribution of granular materials, including soils, powders, sediments, and crushed rock. It characterizes the proportion of particles across a range of size classes, often summarized as a particle size distribution (PSD) curve or as statistics such as D10, D50, and D90. The term covers both the process of separating particles by size and the resulting data used to describe material textures and behavior.

Common methods include sieve analysis for coarse fractions, hydrometer or sedimentation methods for fines, and modern techniques such as laser diffraction, dynamic light scattering, or imaging-based approaches. Dry sieve methods apply to larger particles; sedimentation-based methods rely on settling rates; laser diffraction can span submicron to millimeter scales. PSD data are often plotted as differential or cumulative distributions and used to compute statistics such as mean grain size, sorting, and skewness.

Applications include geotechnical engineering and construction, where granulometry informs soil strength, compaction, and drainage; ceramics, pharmaceuticals, and food processing for quality control; sedimentology and environmental science to interpret transport and deposition; and mining and aggregates to specify material characteristics.

Limitations include dependence on sample preparation and dispersion, particle shape and aggregation, and the measurement range of a given method. No single technique yields perfect accuracy across all sizes, so multiple methods are often used to obtain a complete PSD.