Types / Grades of Cement
Types of Cement - CEM
There are 5 types of cement : CEM I, II, III, IV, V
For general construction use only types I and II are relevant.
CEM I is pure (100%) OPC (Ordinary Portland Cement)
CEM II is a mixture of OPC and additives such as fly ash, slag or limestone, up to a maximum additive content of 35%.
Grades of Cement - 28-Day Strength
Within each type there are three grades, based on the 28-day strength of the concrete that they produce. The grades are 32.5, 42.5 and 52.5 (sometimes written 33, 43, 53).
Classes of Cement - Strength Gain
Each grade consists of 3 classes which describe the speed at which the concrete made from them gains strength:
R = early strength gain
N = normal strength gain
L (or S) = low/slow strength gain.
Additives in CEM II
In the case of CEM II type there are further sub-classifications as follows:
A = additive content <20%
B = additive content 21 to 35%
Furthermore, the type of additive is indicated by letters:
V = fly ash
S = slag
L = limestone
The letter M is used to indicate that it is multi-additive, for example it contains both ash and slag.
Markings / Nomenclature
Typical markings are, for example
- CEM I 42.5 N
- [pure OPC giving strength of 42.5 MPa with 'normal' strength gain.]
- CEM I 52.5 R
- [pure OPC giving strength of 52.5 MPa with 'early' strength gain.]
- CEM II /A-V 42.5 N
- [fly ash content <20% ... of 42.5 MPa with 'normal' strength gain.]
- CEM II /B-M(S-V) 32.5 S
- [slag plus fly ash content <35% ... 32.5 MPa with 'slow' strength gain.]