Types of cement

There are many types of cement in the market to suit every need. Some of them which are included in the revised IS : 456-2000 are as follows:

•Ordinary Portland Cement 33, 43, 53 grade (OPC), 53-S (Sleeper Cement)

•Portland Pozzolana Cement (PPC), both Fly Ash and Calcined Clay based

• Rapid Hardening Portland Cement

• Portland Slag Cement (PSC) 

• Sulphate Resisting Portland Cement (SRC)

• Low Heat Portland Cement

• Hydrophobic Cement

Even though only Ordinary Portland Cement is graded according to strength, the other cements too have to gain a particular strength. 33, 43 and 53 grade in OPC indicates the compressive strength of cement after 28 days when tested as per IS: 4031-1988, eg, 33 Grade means that 28 days of compressive strength is not less than 33 N/mm2 (MPa) . Similarly for 43 grade and 53 grade the 28 days compressive strength should not be less than 43 and 53 MPa respectively. 43 and 53 grade are also being introduced in PPC and PSC shortly by the Bureau of Indian Standards (BIS)

Portland Pozzolana Cement (PPC)

PPC is manufactured by inter grinding OPC clinker with 15-35% of pozzolanic material. Pozzolanas are essentially siliceous or aluminous material, which in itself possesses no cementitious properties, which will be in finely divided form and in the presence of moisture react with calcium hydroxide, liberated in the hydration process, at ordinary temperature, to form compounds possessing cementitious properties. The pozzolanic materials generally used are fly ash or calcined clay. PPC produces less heat of hydration and offers greater resistance to attack of aggressive environment, gives long-term strength and enhances the durability of structures.

Portland Slag Cement (PSC)

PSC is obtained by mixing blast furnace slag, cement clinker and gypsum and grinding them together to get intimately mixed cement. The quantity of slag varies from 30-70%. The gain of strength of PSC is somewhat slower than OPC. Both PPC and PSC will give more strength than that of OPC at the end of 12 months. PPC and PSC can be used in all situations where OPC is used, but are preferred in mass construction where lower heat of hydration is advantageous or in marine situations and structures near seacoast or in general for any structure where extra durability is desired.

The other types of cement listed above are for special purpose and their nomenclature indicates the purpose for which they are preferred. The following table gives the codal requirements at a glance.

Some important requirements to be met by various types of cement

Sl No	Type of cement	IS Code	Fineness m2/kg (min)	Setting Time in minutes		Soundness		Compressive Strength in MPa
				Initial (min.)	Final (max.)	Le Chatelier (mm)	Auto Clave (%)	3 days	7 days	28 days
1	OPC 33	269 : 1989	225	30	600	10	0.8	16	22	33
2	OPC 43	8112 : 1989	225	30	600	10	0.8	23	33	43
3	OPC 53	12269 : 1987	225	30	600	10	0.8	27	37	53
4	PPC (flyash based)	1489 : 1991 (Part 1)	300	30	600	10	0.8	16	22	33
5	PSC (slag)	455 : 2002	225	30	600	10	0.8	16	22	33
6	SRC	12330 : 1988	225	30	600	10	0.8	10	16	33
7	White Cement	8042 : 1989	225	30	600	10	0.8		19.8	29.7
8	RHC (Rapid Hardening Cement)	8041 : 1990	325	30	600	10	0.8	27	16 @ 1 day