Overview
ISO 18985:2025 - Recycled aggregates for concrete - provides a unified framework and minimum requirements for using recycled aggregates produced from construction and demolition waste (primarily waste concrete and demolished masonry). The standard is intended to accelerate the safe, consistent uptake of recycled concrete aggregate (RCA) and recycled fine aggregate (RFA) in concrete production while complementing ISO 19595 (natural aggregates for concrete).
Key topics and technical requirements
ISO 18985 defines principles and technical topics that govern the production, testing and use of recycled aggregates for concrete. Major topics include:
- Scope and definitions: Key terms such as adhered mortar, recycled coarse aggregate (RCA), recycled fine aggregate (RFA), recycled mix aggregate and waste concrete.
- Types and classes: Classification framework for types and classes of recycled aggregates to match intended concrete applications (see Clause 5).
- Geometric requirements: Grading, particle shape, fines content and other size/shape criteria (Clause 6).
- Physical properties: Oven-dry density, water absorption, resistance to fragmentation (LA abrasion) and impurity limits (Clause 7).
- Chemical requirements: Limits and test approaches for chlorides, sulfates and other chemical risks relevant to durability (Clause 8).
- Durability considerations: Soundness, freeze–thaw performance and alkali–silica reactivity evaluation (Clause 9 and Annex C).
- Logistics and QA: Guidance on transportation, storage, sampling, test methods, inspection, marking, labeling and reporting (Clauses 10–14).
- Normative & informative annexes: Annex A (test method for impurity contents), Annex B (application to concrete), Annex C (freezing and thawing tests).
Practical applications and users
ISO 18985 is directly useful for:
- Aggregate producers converting construction and demolition waste into RCA/RFA
- Concrete manufacturers and ready-mix suppliers specifying recycled content and ensuring mix performance
- Contractors, specifiers and design engineers selecting appropriate recycled aggregates for structural and non-structural concrete
- Testing laboratories and quality managers implementing sampling, physical/chemical tests and inspection plans
- Regulators and sustainability programs setting procurement or circular-economy targets to reduce landfill and preserve natural aggregates
Benefits include standardized quality controls, clearer acceptance criteria for recycled materials, improved durability risk management, and facilitation of sustainable concrete use.
Related standards
ISO 18985 complements and references other standards for test methods and sampling, including:
- ISO 19595 (natural aggregates for concrete)
- ISO 20290 series (aggregate test methods)
- ISO 24684-2 (soluble sulfate determination)
- ISO 2859-2 (sampling procedures)
- ASTM C88/88M, EN test methods for aggregate properties
For implementation, consult the full ISO 18985:2025 text and your national standards body for local adoption and conformity requirements.
