Overview
ISO 12439:2010 - Mixing water for concrete defines requirements and assessment methods for water used to make concrete (in accordance with ISO 22965). The standard addresses which water types are acceptable, chemical and physical limits, sampling and testing procedures, reporting, and special provisions for water recovered from concrete industry processes. It is essential for ensuring concrete performance (setting time, strength development) and protection of embedded steel.
Key topics and technical requirements
- Classification of water: potable water (deemed suitable), water recovered from concrete processes, underground water, natural surface and industrial wastewater, sea/brackish water (limited use), and sewage (not suitable).
- Chemical limits (selected highlights):
- Chlorides (Cl−): maximum recommended concentrations - 500 mg/L for pre‑stressed concrete/grout, 1 000 mg/L for reinforced concrete/embedded metal, 4 500 mg/L for concrete without reinforcement.
- Sulfates (SO4 2−): max 2 000 mg/L.
- Alkali (expressed as Na2O equivalent): max 1 500 mg/L when alkali‑reactive aggregates may be present (requires mitigation if exceeded).
- Harmful substances: sugars and phosphates 100 mg/L, nitrates 500 mg/L, lead and zinc 100 mg/L (qualitative screening followed by quantification if positive).
- Performance checks:
- Setting time: initial setting ≥ 1 hour and within ±25% of distilled/de‑ionized water; final setting ≤ 10 hours and within ±25%.
- Strength: mean compressive strength at 7 and 28 days ≥ 90% of specimens made with distilled/de‑ionized water.
- Sampling & testing:
- Minimum sample 5 L, stored sealed, tested within 2 weeks.
- Preliminary visual/odour/pH checks, chemical tests using referenced ISO methods (e.g., ISO 29581‑1 for chlorides/sulfates, ISO 7890‑1 for nitrates).
- Testing frequency: potable water - no testing required; recovered/process and non‑potable sources - initial and periodic testing (monthly until stable); sea/brackish - annually or as needed.
Practical applications
- Ensures durability and performance of concrete mixes used in structures with reinforced or pre‑stressed steel.
- Guides use of alternative waters (process‑recovered, groundwater, surface water, brackish/sea water) while controlling risks (corrosion, alkali‑silica reaction, setting/strength loss).
- Supports quality control in precast plants, ready‑mix producers, on‑site concrete production, and remediation projects where non‑potable sources are considered.
Who should use ISO 12439:2010
- Concrete producers, quality managers, laboratory technicians, specifiers, construction engineers, and regulatory bodies responsible for concrete production and compliance.
Related standards
Keywords: ISO 12439, mixing water for concrete, water for concrete, chloride limits, sulfate limits, recovered process water, sampling and testing, potable water, reinforced concrete.
