Clinker is the key intermediate product used to manufacture cement. It is produced by heating limestone and clay in a rotary kiln at about 1,400–1,500°C, forming hard gray nodules that are later ground with gypsum to make cement.

Main Clinker-Based Products

1. Ordinary Portland Cement (OPC) Clinker

   • Used to produce OPC cement.

   • Common in buildings, roads, and general construction.

2. Sulphate Resistant Clinker

   • Used where structures are exposed to sulphate-rich soils or water.

   • Suitable for marine and sewage projects.

3. Low Heat Clinker

   • Produces less heat during hydration.

   • Used in dams and mass concrete works.