Manufactured cements are those made in a cement factory. Where a mineral material is included, it is generally added to the cement clinker at the grinding stage. The notation used for these manufactured cements contains the prefix letters CEM. When a concrete producer adds an addition such as pfa or ggbs to CEM I Portland cement in the mixer, the resulting cement is known as a mixer combination, and is denoted by the prefix letter C. Cements and combinations in general use are listed in Table 2.17 . Further information on the different types and use of cements is given in section 3.1.1.