About this tool Assess chloride content in concrete against BS EN 206 corrosion limits. Enter the chloride concentration from lab testing and optionally the cement content to convert between % by mass of concrete and % by mass of cement.
Results are classified against four corrosion risk levels and checked against all BS EN 206 chloride classes (CL 0.10 to CL 1.0). Exceedances are flagged with the specific limit and application type (prestressed, reinforced, unreinforced).
Essential for condition surveys of reinforced concrete structures exposed to de-icing salts, seawater, or industrial chlorides. Standard: BS EN 14629 (determination), BS EN 206 (limits), Concrete Society TR 31.
How to use this tool 1. Enter chloride content — as % by mass of concrete from the lab certificate.
2. Enter cement content (optional) — if known, converts to % by cement for direct comparison against BS EN 206 Table 10 limits.
Technical information Cl (% by cement) = Cl (% by concrete) × (2400 / cement content)
BS EN 206 limits: CL 0.10 (prestressed), CL 0.20 (reinforced), CL 0.40 (reinforced, some conditions), CL 1.0 (unreinforced). Conversion assumes concrete density of 2,400 kg/m³.
Limitations The conversion from % by concrete to % by cement assumes a concrete density of 2,400 kg/m³. For lightweight or heavyweight concrete, adjust accordingly.
Chloride content alone does not determine corrosion activity. Corrosion also requires moisture, oxygen, and a breakdown of the passive layer. A full corrosion assessment should include half-cell potential and resistivity measurements.
Lab results may report acid-soluble or water-soluble chloride. BS EN 206 limits are for acid-soluble chloride per BS EN 14629. Water-soluble values will be lower.
Revision history 18 August 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
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