4.2 : ポルトランドセメント

Portland cement, the binding ingredient in concrete, is produced from calcareous materials, rich in lime and argillaceous materials, containing silica, alumina, and iron oxide.

The raw materials are crushed in crushers and stored in silos. These are then proportioned and advanced to the grinding mill and ground to powder form.

In the dry mixing process, the powder is dry-mixed, blended, and stored in silos. Alternatively, in wet mixing, the powder is mixed with water to form a slurry, blended, and stored in basins.

The mixture is then passed to a rotary kiln, and heated to produce clinker, which is subsequently cooled and stored.

Later, a small amount of gypsum is added to the clinker and transferred to a grinding mill to be pulverized into fine Portland cement powder.

Portland cement primarily consists of four main compounds: tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.

Based on the variation in these constituents, Portland cement is categorized into different types, with ordinary Portland Cement, also known as Type I, being the most widely used.