Slag cement, GGBS or GGBFS (ground granulated blast furnace slag) is a by-product of the steel and iron industry, which is dried and ground down to a fine powder.

Architectural and Engineering Benefits


A key characteristic of slag is that it possesses self-cementing properties. It’s been found that slagment can double the lifespan of buildings. This latent hydraulic binder is used in concrete and has other uses in construction as a partial cement replacement material. It is also a direct replacement for ordinary Portland cement by weight. Slagment is usually used as an optional additive to cement and concrete mixes. The main function is to increase durability and workability. Used together with lime and/or cement it stabilises the soil prior to road construction.


Slagment provides protection from both chloride and sulphate attack. It reduces the thermal gradient generated when pouring the concrete. This in turn reduces the likelihood of micro cracking which reduces the structure’s strength.


Slagment can alter the colour of concrete to a near-white colour by replacing 50-70% of the concrete. The high slag content also produces a smoother more defect free surface.

Operations and Capacity

Our plant in Vanderbijl Park can produce over 800 000 tons of slagment and over 200 000 tons of blended cementitious products per year. We’ve produced slag for over the last 50 years, building major structures such as dams, bridges and roads.

Custom-made Slagment

We produce a number of different Slagment products including custom-made products such as:

  • A binder used for backfill in the mining industry, generally for cut-and-fill or room-and-pillar backfilling where high early strength gain is not required
  • A binder designed for use with classified or unclassified mine tailing in backfill systems in deep level mining

Become a Vendor

It's important to us that you, our customers, are able to contact us easily. For each of our product lines, our call centre staff are well-trained to process quotations, place orders and handle delivery queries.

South African national quotations and orders:
Telephone: Facsimile:
National ordering/quotations: (011) 670 5555
0860 110 010 (sharecall)
(011) 670 5797
Exports: (011) 670 5619 (011) 670 5119
International sales, quotations and orders:
Telephone: Facsimile:
Lesotho sales office: (00266) 22 32 3144 (00266) 22 32 3142
Namibia sales office: (00264) (61) 26 7500 (00264) (61) 26 2205
Swaziland sales office: (00268) 518 7078 (00268) 518 5081
Botswana sales office: (011) 670 5555 (011) 670 5797