About this tool Classify aggressive ground conditions for concrete design per BRE Special Digest 1 (2005). Enter sulfate concentrations, pH, and site conditions — the tool determines the Design Sulfate (DS) class, Aggressive Chemical Environment for Concrete (ACEC) class, and the Design Chemical (DC) class for concrete specification per BS 8500-1.
Supports AGS file upload — drag and drop an AGS file and the tool will extract pH, sulfate, and magnesium results from the GCHM (Geotechnical Chemistry) group automatically, using worst-case values across all samples.
Standards: BRE Special Digest 1 (2005, 3rd edition), BS 8500-1 (concrete specification), BS EN 206 (concrete performance).
How to use this tool 1. Enter sulfate data — at least one of: TPS (% SO4), water-soluble SO4 (g/l), or groundwater SO4 (mg/l). The worst case governs.
2. Enter pH and magnesium (optional) — pH ≤ 2.5 overrides to DS-5. High Mg triggers a cement-type warning.
3. Select site type and water condition — natural vs brownfield, static vs mobile groundwater.
4. Or upload an AGS file — GCHM data is extracted automatically and worst-case values populate the inputs.
Technical information DS class per BRE SD1 Table 1 — boundaries: DS-1 (<0.24% TPS, <0.4 g/l, <400 mg/l), DS-2 (0.24–0.6, 0.4–1.4, 400–1400), DS-3 (0.7–1.2, 1.5–3.0, 1500–3000), DS-4 (1.3–2.4, 3.1–6.0, 3100–6000), DS-5 (>2.4, >6.0, >6000 or pH ≤2.5)
ACEC class per BRE SD1 Table 2 — depends on DS class, site type (natural/brownfield), and groundwater condition (static/mobile)
DC class per BS 8500-1: AC-1→DC-1, AC-2→DC-2, AC-3→DC-3, AC-4→DC-4, AC-5→DC-4+APMs
Limitations This tool implements the BRE SD1 (2005) classification. The user must verify that SD1 is the appropriate standard for their project — some projects may require assessment to different criteria (e.g. Highways England CD 622).
The tool does not specify detailed concrete mix requirements (cement content, w/c ratio, cement type) which depend on the specific DC class and cement combination selected. Refer to BS 8500-1 Tables A.9–A.13 for full specification.
High magnesium (>1000 mg/l) is flagged as a warning. The exact impact on concrete specification depends on the magnesium-to-sulfate ratio and should be assessed by a specialist.
Revision history 13 October 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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