Fly ash and slag cements
While cements containing fly ash or GGBS have different strength properties to ordinary Portland cement, they also benefit from improved durability and workability. A key factor in strength development is the provision of calcium silicate hydrate.

Concrete made with cement which includes fly ash or ggbs will have different strength properties than that
made with cement which contains purely clinker and gypsum
Although a particular material may be cheaper per kilogram or per tonne than another, a customer for a concrete order will require particular qualities from a cement, notably strength. Despite the varying requirements for different contracts, the usual measure of a concrete’s quality is the 28-day compressive strength.