Fly ash or GGBS?
Fly ash and ground granulated blastfurnace slag (GGBS) are regarded as conventional cement constituents in much of the world. The proportions used in concrete-making vary quite considerably and the price of the material is key when it comes to producing a cubic metre of concrete to the required specification at the lowest possible cost.
The terminology for fly ash and GGBS in concrete has varied over the years – they have been fillers, extenders, cementitious materials, cement replacement materials, even cements. Although there are some similarities with the Portland cement clinker which they replace in cements, it is worth looking at the differences between the two to better understand their particular benefits.