ISO 3262-8:2023 PDF

Overview

ISO 3262-8:2023 - Extenders: Specifications and methods of test - Part 8: Natural clay specifies requirements and corresponding test methods for naturally occurring hydrated aluminium silicates (primarily kaolinite) used as extenders. This second edition updates test references and presents the Andreasen method as the referee procedure for particle-size distribution. The standard covers composition limits, physical fractions, sampling and detailed laboratory procedures needed to demonstrate conformity.

Key topics and requirements

• Scope and definitions - Natural clay defined as hydrated aluminium silicates with lamellar crystal structure (predominantly kaolinite).
• Grades and essential requirements (Table 1) - Typical requirements by grade include:
  • Kaolinite content: Grade A ≥ 90%; Grade B ≥ 85%; Grade C ≥ 70%; Grade D ≥ 50% (by X‑ray diffraction or agreed method).
  • Residue on 45 µm sieve: max 0.02–0.5% depending on grade (ISO 787-7).
  • Particle-size distribution (Andreasen method) - percentage