Blue Circle Ground Granulated Blastfurnace Slag (GGBS)

GGBS (BS EN 15167-1)

A cementitious addition, typically mixed with CEM I at 30-50%, suitable for use in concrete:

  • Large pours, to reduce the risk of early-age thermal cracking.
  • Reducing attack on concrete in sulfate conditions.
  • Improved surface finish of concrete.

Contact our Customer Service team on 0845 812 6300



Regional Order Numbers:

Scotland & North East England – 0845 4700 300

North & Midlands – 0845 4700 400

South Wales & South West – 0845 4700 500

London & South East – 0845 4700 600


Strength gain after 28 days

Chloride Resistance

Enhanced resistance to chloride ingress

Reduces Alkali Risk

Reduces risk of Alkali-Silica Reaction


Enhanced sulfate resistance

Low CO2

Lower embodied CO2 than CEM I Portland cement

Quality Assurance

Quality is assured with independent third party certification and a CE Mark.

Technical Information

GGBS is available in bulk tankers in Southern England.


CEM I/GGBS concrete – when compared with Tarmac bulk Portland cement concrete at the same cement content – has the following properties:

  • Slower strength development and potentially higher long-term strength.
  • The appropriate cement content for concrete of a given 28 day cube strength and slump should be determined from trial mixes.
  • The cement content may differ from that of an equivalent Portland cement (CEM I) concrete in certain circumstances. In particular, where a high strength concrete is required, the cement content may be slightly higher than for CEM I.
  • Slower setting times.
  • Reduced water demand.
  • Improved placing and finishing.
  • Lighter in colour

Conditions of Use:

  • Concrete, mortars and grouts containing Portland Cements and GGBS must be specified and used correctly for best performance.
  • The cement content must be correct and the water: cement ratio as low as possible consistent with satisfactory placing, thorough compaction and effective curing.
  • The final finish quality of this material will depend upon the operative having the required skills and a familiarisation with the materials and its application methods.
  • Tarmac cannot be held responsible where workmanship has not been carried out in accordance with good practice.

Regional Order Numbers:

London & South East – 0845 4700 600

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