Ground Granulated Blastfurnace slag

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.


  1. Strength

    Strength gain after 28 days

  2. Chloride Resistance

    Enhanced resistance to chloride ingress

  3. Reduces Alkali Risk

    Reduces risk of Alkali-Silica Reaction

  4. Resistance

    Enhanced sulfate resistance

  5. Lower CO2

    Lower embodied CO2 than CEM I Portland cement

  6. Quality Assurance

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


  • Soil Stabilisation
  • Grout
  • Drainage
  • Concrete Block Paving
  • Blocks
  • Power
  • Waste
  • Wind Farms
  • Infrastructure
  • Major Contracts
  • Nuclear
  • Marine

Technical Information

CEMblend 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

  • Achillies Building Confidence
  • Carbon Trust Standard

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