The Material

GGBS is a cementitious white powder, which is used in concrete as a 'cement replacement'. Its major use is in ready-mixed concrete, with a third of all UK ready-mixed concrete deliveries containing GGBS. It is also used in site-batched and pre-cast concrete and in applications such as soil stabilisation.

GGBS can replace a substantial portion of the Portland cement content, generally about 50%, but sometimes up to 70% or more. The higher the proportion, the better is the durability. Concrete containing GGBS is less permeable and chemically more stable than normal concrete. This enhances its resistance to many forms of deleterious attack, in particular:

• disintegration due to sulfate attack
• chloride-related corrosion of reinforcement
• cracking caused by alkali silica reaction.

There are other benefits from using GGBS in concrete, including:

• greatly reduced carbon dioxide emissions
• better workability
• reduced early-age temperature rise
• lighter colour