Why C₃A decides sulfate resistance
In sulfate-bearing soil or groundwater, sulfate reacts with the hydrated tricalcium aluminate (C₃A) in set cement to form ettringite, which expands and cracks the concrete from inside. The less C₃A, the less the reaction has to feed on. That is the whole difference between the grades below.
| Product | C₃A | Sulfate resistance | Where it fits |
|---|---|---|---|
| Portland Type I-425 | 7.2% | Normal | General structural concrete |
| Portland Type II | 6.4% (max 8) | Moderate | Foundations in sulfate-bearing ground, mass pours |
| Type V clinker | max 5% | High | Grinding plants making sulfate-resisting cement |
| API Class G HSR | 1.90% (max 3) | High | Oil and gas well cementing |
Type II cement for GCC projects
Type II is the cement for concrete cast against moderately sulfate-bearing soil or groundwater — foundations, buried pipes, culverts, retaining walls — and for mass pours, where its lower heat of hydration limits thermal cracking. It does not trade away strength; it reaches it slightly more slowly.
| Property | ISIRI 389 limit | Result |
|---|---|---|
| C₃A | max 8% | 6.4% |
| SO₃ | max 3% | 2.20% |
| MgO | max 5% | 1.75% |
| Loss on ignition | max 3% | 1.19% |
| Compressive strength, 3 days | min 100 kg/cm² | 220 kg/cm² |
| Compressive strength, 7 days | min 175 kg/cm² | 320 kg/cm² |
| Compressive strength, 28 days | min 315 kg/cm² | 450 kg/cm² |
| Initial / final set | min 45 min / max 6 h | 140 min / 3 h |
| Autoclave expansion | max 0.8% | 0.06% |
Values are typical mill results; a batch-specific mill test certificate is issued per shipment. Store dry and covered, bags off the ground and away from walls, and use within three months of production for full rated strength.
Product specification Portland cement Type II, moderate sulfate resistant Full ISIRI 389 chemistry and physical tests: C₃A 6.4%, 450 kg/cm² at 28 days.Iraq: buy the clinker, grind it locally
Iraq restricts imports of grey cement, so the route into Iraqi construction is through its grinding plants. For sulfate-resisting cement they need Type V clinker, where alumina is cut and iron raised to suppress C₃A:
| Parameter | Range |
|---|---|
| C₃A | max 5% |
| C₄AF + 2×C₃A | ≤ 25% |
| CaO | 63–66% |
| SiO₂ | 21–24% |
| Al₂O₃ | 3–4.5% |
| Fe₂O₃ | 4–5% |
| SO₃ (before gypsum) | max 2.3% |
| Free CaO | max 1% |
These are typical ranges for the kiln line we ship from, not a single certificate; every shipment carries a batch mill certificate with the actual oxide analysis and Bogue phases. Clinker reaches Iraq overland by truck or by sea from Bandar Imam Khomeini.
Product specification Cement clinker: grey, Type V and white Typical oxide ranges, Bogue phases and trading terms for each clinker. Buyer's guide Cement clinker export to Iraq, Afghanistan and Central Asia Choosing a clinker grade, reading the mill certificate and the overland routes.Shipping to the GCC and Iraq
- GCC: Type II cement FOB Bandar Abbas or Bandar Imam Khomeini, with CFR and CIF to most Gulf ports.
- Iraq: Type V clinker overland by truck on DAP or FCA terms, or by sea.
- Cement packaging: 30 × 50 kg PP or paper bags loaded inside a jumbo bag for faster loading and discharge, 1.5 MT jumbo bags, or bulk vessel for tonnages above 25,000 MT.
- Clinker packaging: bulk as standard; jumbo bags by container for trial quantities.
| Item | Terms |
|---|---|
| Minimum order | 1 × 20 ft container (approx. 25 MT) bagged; 500 MT for a bulk vessel; trial quantities for qualification |
| Lead time | 7–14 days for standard grades after order confirmation |
| Certification | Batch mill certificate with full chemistry and physical tests; SGS, Bureau Veritas or your inspector at the buyer's cost |
| HS code (6-digit) | Portland cement 2523.29; cement clinker 2523.10 — national subheadings vary |
Specifying sulfate resistance
- Start from the exposure, not the cement name: send the sulfate class of the soil or water and the standard your project specifies.
- Moderate exposure is Type II territory; severe exposure needs C₃A below 5%, which means Type V.
- For a grinding plant, check C₃A and C₄AF + 2C₃A on every clinker certificate, not just the first.
- Trial before contract: a 25 MT container lets you cast your own cubes or run your own mill first.