Being recycled, slag is a 'Green' material. When using slag as an additive in the kiln, cement manufacturers are producing a product which has the same properties as traditional cement, but with the advantage of a lower Co2 emissions, which lowers carbon footprint of buildings which are built using slag cement.
The cementitious properties of iron and steelmaking slag are well known.
Blast furnace (BF) slags
The most common slag cement is GGBFS (Ground Granulated Blast Furnace Slag), whereby BF slag is water granulated, and then milled to fine powder.
- Blaine approx 320 m2 per kg
- Used directly in cement
Similar cementitious properties can be realised from BOS slags via fine milling. This process has been progressively developed by Harsco in China over a number of years.
In Zhejiang province, China, Harsco has developed a BOF Slag Superfine cement substitute product. When blended with cement, it produces the same quantities and gives desirable properties such as long term strength, high elasticity and crack resistance. The Superfine product has a better effect in reducing the heat of hydration than Portland Cement or Blast Furnace Slag - preventing cracking on large pours. It also has a corrosion resistance quality because of the lack of sand, water and wearables within the product.
Superfine is used in construction material manufacture - namely as a cement substitute for concrete based building, marine & large construction projects.