Sulphate Resisting Cement (SRC): Properties, Uses, and Advantages

Sulphate Resisting Cement (SRC) is a specialized type of Portland cement formulated to resist the destructive effects of sulphate salts present in soil, groundwater, and seawater. It is widely used in construction projects where structures are exposed to severe sulphate attack, ensuring longer durability and minimal deterioration over time.

What is Sulphate Resisting Cement (SRC)?

Sulphate Resisting Cement is a modified form of Ordinary Portland Cement (OPC) with a reduced percentage of tricalcium aluminate (C3A), typically limited to less than 5%. By lowering the C3A content, SRC significantly reduces the risk of sulphate attack, which often leads to expansion, cracking, and structural weakening. This makes it highly suitable for foundations, marine works, and hydraulic structures.

Chemical Composition of Sulphate Resisting Cement

The chemical composition of SRC is carefully designed to enhance its resistance to sulphates. The typical composition includes:

• Lime (CaO): 60–67%
• Silica (SiO2): 17–25%
• Alumina (Al2O3): 3–8% (with C3A < 5%)
• Iron Oxide (Fe2O3): 0.5–6%
• Magnesia (MgO): 0.1–4%
• Sulphur Trioxide (SO3): 1–3%
• Alkalies (Na2O, K2O): 0.2–1%

The reduced alumina content makes SRC superior in areas with high sulphate concentration.

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