Overview
ISO 20977:2018 - Liming materials - Determination of size distribution by dry and wet sieving - specifies two standardized sieving methods to determine the particle size distribution of liming materials. It defines when to use the dry sieving method (Method A) and the wet sieving method (Method B), outlines sampling and test‑portion requirements, required apparatus, procedural steps and reporting. Results are expressed on a dry matter basis to ensure comparability.
Key topics and technical requirements
- Scope & applicability
- Method A (dry sieving): applicable to most liming materials except wet or paste‑like products; not suitable if drying causes blinding, caking, electrostatic agglomeration.
- Method B (wet sieving): for materials prone to blinding/caking after drying and for determining primary particle size of granules; not applicable to burnt lime or liming materials containing water‑soluble constituents.
- Sampling & test portion
- Follow ISO 14820‑1 for sampling. Minimum test portion size is 100 g; divide laboratory sample into equal test portions.
- Apparatus
- Test sieves conforming to ISO 3310‑1/ISO 565, mechanical shaker (or hand sieving), balance (0.01 g), oven (105 ± 2 °C), soft brush, stopwatch.
- Procedure highlights
- Perform at least two single determinations from the same laboratory sample.
- Use up to seven sieves covering expected size range; assemble in ascending aperture order.
- Dry sieving: shake for exactly 10 minutes on mechanical shaker; brush mesh to recover retained particles.
- Wet sieving: disperse material in tap water (pH > 6.4), continuous spraying during sieving, dry retained fractions before weighing.
- Dry samples in oven per EN 12048 when required; express masses as dry matter.
- Safety
- When testing burnt or hydrated lime, use fume hood and gloves to avoid inhalation and skin contact.
- Precision & reporting
- The standard includes repeatability/reproducibility guidance and test report requirements to ensure comparable results.
Practical applications and users
ISO 20977:2018 is used by:
- Fertilizer and soil conditioner manufacturers for product specification and quality control.
- Analytical laboratories performing particle size analysis of liming materials.
- Agricultural suppliers, regulators and certification bodies requiring standardized particle size data for product labeling, performance assessment and compliance.
- Ensures consistent assessment of fineness affecting reactivity, spreadability and agronomic performance.
Related standards
Keywords: ISO 20977:2018, liming materials, particle size distribution, dry sieving, wet sieving, sieve analysis, test sieves, fertilizer quality.