Cement strength class according to DIN EN 197-1

According to DIN EN 197-1, standard cements are classified as follows:

• CEM I (Portland cement)
• CEM II (e.g. Portland cement)
• CEM III (blast furnace cement)
• CEM IV (pozzolan cement)
• CEM V (composite cement)

The cement strength class refers to the strength development of normal cement after the start of the hydration process. Normal cement is divided into three classes according to its tested minimum compressive strength after 28 days (= standard strength):

• Class 32.5
• Class 42.5
• Class 52.5

While the standard strength indicates the strength after 28 days, the additives L (low), N (normal) and R (rapid) are used to classify the strength in the early phase of hardening after 2 or 7 days (= initial strength). The exact values can be found in DIN EN 197-1:

• L: low initial strength (applies only to CEM III cements = blast furnace cements)
• N: usual initial strength
• R: fast initial strength

Source: bauwion