Editing Portland cement (section)

===EN 197 norm===
The European norm [[European Committee for Standardization|EN]] 197-1 defines five classes of common cement that comprise portland cement as a main constituent. These classes differ from the ASTM classes.
{|class="wikitable"
! Class 
! Description 
! Constituents
|-
|CEM I||Portland cement||Comprising portland cement and up to 5% of minor additional constituents
|-
|CEM II||Portland-composite cement||Portland cement and up to 35% of other* single constituents 
|-
|CEM III||Blast furnace cement||Portland cement and higher percentages of blast furnace slag
|-
|CEM IV||Pozzolanic cement||Portland cement and up to 55% of [[pozzolan|pozzolanic constituents]]
|-
|CEM V||Composite cement||Portland cement, blast furnace slag or fly ash and pozzolana
|}

{{asterisk}}''Constituents that are permitted in portland-composite cements are artificial pozzolans (blast furnace slag (in fact a latent hydraulic binder), silica fume, and fly ashes), or natural pozzolans (siliceous or siliceous aluminous materials such as volcanic ash glasses, calcined clays and shale).''