Classification & Types of Cement

This Topic covers the classification of cement and its types as per:
1. ASTM Classification
2. IS Specifications

1. American Society for Testing Materials (ASTM)

As per ASTM , Cement is designated as
a) Type I   b)Type II   c)Type III   d)Type IV  e)Type V 

Type I (Ordinary Portland Cement)

•  Used for general construction work when the special properties of the other types are not required.
•  Normally used for reinforced concrete buildings, bridges, pavements and sidewalks when the soil conditions are normal, for concrete masonry units, and for all uses where the concrete is not subjected to special sulfate hazard, heat of hydration is not objectionable, where freezing thawing is not expected. 

Type I A (OPC with Air Entraining Agent)

• It is used where air entrainment is necessary. 
• Air-entrainment:Air intentionally incorporated by means of a suitable agent.
• Magnitude of these air bubbles are in the order of 0.05 mm in size.
• Entrained air produces separate cavities in the cement paste so that no channels for the passage of water are formed and the permeability of the concrete is not increased. 
• The voids never become filled with the products of hydration of cement as gel can form only in water.

Type II (Modified Portland Cement):

•  It has better resistance to the action of sulfates than normal (ordinary) Portland cement and used where sulfate concentrations in groundwater are higher than normal but not very severe. 
• Generates heat at a slower rate than OPC and is used in certain concrete mass work like retaining walls.
•  Reduced temperature rise is beneficial for hot weather concrete, too. 

Type II-A (Air-Entrained Type II Cement) 

Type III: (High Early Strength Cement)

• Used where high early strengths are required at early periods, usually a week or less.
•  It is particularly usefull where it is required to remove forms as soon as possible or when the structure must be brought into service quickly. 
• High-early strength makes it possible to reduce the period of Total protection for concrete during cold weather. 

Type III-A (Air Entrained Type III)

Type IV (Low Heat Portland Cement):

• It is used where the amount and rate of heat generation must be minimized. 
• Strength is also developed at a slower rate.
• It is intended for use in massive concrete structures such as dams.

Type V (Sulfate Resistant Portland Cement):

• It is used in structures subject to sulfate attack, chemical plants, etc.
• It is also resistant to the action of sea water.

2) IS Specifications

1. OPC- Ordinary Portland Cement

There are three different types of ordinary Portland cement, classified on the basis of strength achieved in 28 days.

i) 33 Grade

ii) 43 Grade

iii) 53 Grade

Other Types of cements used in India are as follows: