Types of portland cement
The ASTM(American Society for Testing and Materials) classified cement into 5 types. this classification based on there physical and chemical properties. cement fineness, the rate of hydration and resistance for sulfate are different for each type.
- Type I: it is ordinary Portland cement. used for the construction of building and bridges.
- Types II: moderate sulfate resistance. this type of cement used for a structural member that in direct contact with soil or water with sulfate ions higher than usual but not sever.
- Type III: High early strength cement. this type contains fine grounds more than other types. therefore the rate of hydration is higher than other types. increasing fine particles will increase the surface area available to interact with water and this will accelerate the hydration process. the cement will gain high strength within one week. however, the strength at 28 days will not differ significantly from type I. this type of cement used in rapid construction and cold weather concreting
- Type IV: low heat of hydration cement. this type of cement is not produced anymore. in the past, it used for massive structures such as dams. the high heat of hydration will cause tensile stresses on concrete and this will lead to cracks. nowadays pozzolan and slag are used to control cement temperature.
- Type V: high sulfate resistance cement. this type of cement is used in aggressive environment where the soil and water with high sulfate content. this type of cement is rarely produced. nowadays using of pozzolan and slag are more common to control sulfate attack.
sulfate ions are destructive for concrete. sulfate ions react with c3a(tricalcium aluminate) in cement. this reaction will increase the volume of concrete. this will generate stresses on concrete and lead to crack or concrete spalling. therefore, the content of c3a in type II and V are low.
Table 1 showing the composition of different cement types. you can notice eight types of cement. type I and IA. Type IA is the same as type I but with air entraining. the same for type II, IIA and typeIII, IIIA
Table 3 showing the standard physical requirement for cement.