Cement is a binding material that has both adhesive and cohesive properties due to which it can make bonding an bind particle (bond between cement and aggregate)
(a) Ordinary Portland Cement
Ordinary Portland Cement 33 Grade– IS 269: 1989
Ordinary Portland Cement 43 Grade– IS 8112: 1989
Ordinary Portland Cement 53 Grade– IS 12269: 1987
(b) Rapid Hardening Cement – IS 8041: 1990
(c) Extra Rapid Hardening Cement – IS 8041: 1990
(d) Super Sulphated Cement – IS 6909: 1990
(e) Portland Slag Cement – IS 455: 1989
(f ) Quick Setting Cement – IS 455: 1989
(g) Sulphate Resisting Cement – IS 12330: 1988
(h) Low Heat Cement – IS 12600: 1989
(i) Rediset Cement – IS 8229: 1986
(j) High Alumina Cement – IS 6452: 1989
(k) Portland Pozzolana Cement – IS 1489 (Part I) 1991 (fly ash based)
– IS 1489 (Part II) 1991 (calcined clay based)
(l) Air Entraining Cement – IS 1489
(m) Oil Well Cement – IS 8229: 1986
(n ) Coloured Cement: White Cement – IS 8042: 1989
(o) Hydrophobic Cement – IS 8043: 1991
(p) Masonry Cement – IS 3466: 1988
(q) Expansive Cement – IS 3466: 1988
(r ) Concrete Sleeper grade Cement – IRS-T 40: 1985
(a) Ordinary Portland Cement
Ordinary Portland cement (OPC) is by far the most important type of cement. there was only one grade of OPC which was governed by IS 269-1976. After 1987 higher grade cements were introduced in India. The OPC was classified into three grades, namely 33 grade, 43 grade and 53 grade depending upon the strength of the cement at 28 days when tested as per IS 4031-1988. If the 28 days strength is not less than 33N/mm2, it is called 33 grade cement, if the strength is not less than 43N/mm2, it is called 43 grade cement, and if the strength is not less then 53 N/mm2, it is called 53 grade cement. But the actual strength obtained by these cements at the factory are much higher than the BIS specifications.
It has been possible to upgrade the qualities of cement by using high quality limestone, modern equipments, closer on line control of constituents, maintaining better particle size distribution, finer grinding and better packing. Generally use of high grade cements offer many advantages for making stronger concrete. Although they are little costlier than low grade cement, they offer 10-20% savings in cement consumption and also they offer many other hidden benefits. One of the most important benefits is the faster rate of development of strength. In the modern construction activities, higher grade cements have become so popular that 33 grade cement is almost out of the market. Table 2.9 shows the grades of cement manufactured in various countries of the world.
The manufacture of OPC is decreasing all over the world in view of the popularity of blended cement on account of lower energy consumption, environmental pollution, economic and other technical reasons. In advanced western countries the use of OPC has come down to about 40 per cent of the total cement production. In India for the year 1998-99 out of the total cement production i.e., 79 million tons, the production of OPC in 57.00 million tons i.e., 70%. The production of PPC is 16 million tone i.e., 19% and slag cement is 8 million tons i.e., 10%. In the years to come the use of OPC may still come down, but all the same the OPC will remain as an important type for general construction.
(b) Rapid Hardening Cement – IS 8041: 1990
This cement is similar to ordinary Portland cement. As the name indicates it develops strength rapidly and as such it may be more appropriate to call it as high early strength cement. It is pointed out that rapid hardening cement which develops higher rate of development of strength should not be confused with quick-setting cement which only sets quickly. Rapid hardening cement develops at the age of three days, the same strength as that is expected of ordinary Portland cement at seven days.
A higher fineness of cement particles expose greater surface area for action of water and also higher proportion of C3S results in quicker hydration. Consequently, capid hardening cement gives out much greater heat of hydration during the early period. Therefore, rapid hardening cement should not be used in mass concrete construction.
The use of rapid heading cement is recommended in the following situations:
(a) In pre-fabricated concrete construction.
(b) Where formwork is required to be removed early for re-use elsewhere,
(c ) Road repair works,
(d ) In cold weather concrete where the rapid rate of development of strength reduces the vulnerability of concrete to the frost damage.
(c) Extra Rapid Hardening Cement – IS 8041: 1990
Extra rapid hardening cement is obtained by intergrinding calcium chloride with rapid hardening Portland cement. The normal addition of calcium chloride should not exceed 2 percent by weight of the rapid hardening cement. It is necessary that the concrete made by using extra rapid hardening cement should be transported, placed and compacted and finished within about 20 minutes. It is also necessary that this cement should not be stored for more than a month.
Extra rapid hardening cement accelerates the setting and hardening process. A large quantity of heat is evolved in a very short time after placing. The acceleration of setting, hardening and evolution of this large quantity of heat in the early period of hydration makes the cement very suitable for concreting in cold weather, The strength of extra rapid hardening cement is about 25 per cent higher than that of rapid hardening cement at one or two days and 10–20 per cent higher at 7 days. The gain of strength will disappear with age and at 90 days the strength of extra rapid hardening cement or the ordinary portland cement may be nearly the same.
There is some evidence that there is small amount of initial corrosion of reinforcement when extra rapid hardening cement is used, but in general, this effect does not appear to be progressive and as such there is no harm in using extra rapid hardening cement in reinforced concrete work. However, its use in prestress concrete construction is prohibited .
(d) Super Sulphate Cement – IS 6909: 1990
Super sulphated cement is manufactured by grinding together a mixture of 80-85 percent granulated slag, 10-15 per cent hard burnt gypsum, and about 5 per cent Portland cement clinker. The product is ground finer than that of Portland cement. Specific surface must not be less than 4000 cm2 per gm. The super-sulphated cement is extensively used in Belgium,where it is known as “ciment metallurgique sursulfate.” In France, it is known as “cimentsursulfate”.
This cement is rather more sensitive to deterioration during storage than Portland cement.
Super-sulphated cement has a low heat of hydration of about 40-45 calories/gm at 7 days and 45-50 at 28 days. This cement has high sulphate resistance. Because of this property this cement is particularly recommended for use in foundation, where chemically aggressive conditions exist. As super-sulphated cement has more resistance than Portland blast furnace slag cement to attack by sea water, it is also used in the marine works. Other areas where super-sulphated cement is recommended include the fabrication of reinforced concrete pipes which are likely to be buried in sulphate bearing soils. The substitution of granulated slag is responsible for better resistance to sulphate attack.
Super-sulphated cement, like high alumina cement, combines with more water on hydration than Portland cements. Wet curing for not less than 3 days after casting is essential as the premature drying out results in an undesirable or powdery surface layer. When we use super sulphated cement the water/cement ratio should not be less than 0.5. A mix leaner than about 1:6 is also not recommended.
(e) Portland Slag Cement – IS 455: 1989
Portland slag cement is obtained by mixing Portland cement clinker, gypsum and granulated blast furnace slag in suitable proportions and grinding the mixture to get a thorough and intimate mixture between the constituents. It may also be manufactured by separately grinding Portland cement clinker, gypsum and ground granulated blast furnace slag and later mixing them intimately. The resultant product is a cement which has physical properties similar to those of ordinary Portland cement. In addition, it has low heat of hydration and is relatively better resistant to chlorides, soils and water containing excessive amount of sulphates or alkali metals, alumina and iron, as well as, to acidic waters, and therefore, this can be used for marine works with advantage.
The manufacture of blast furnace slag cement has been developed primarily to utilize blast furnace slag, a waste product from blast furnaces. The development of this type of cement has considerably increased the total output of cement production in India and has, in addition, provided a scope for profitable use for an otherwise waste product. During 98-99 India produced 10% slag cement out of 79 million tons.
The quantity of granulated slag mixed with portland clinker will range from 25-65 percent. In different countries this cement is known in different names. The quantity of slag mixed also will vary from country to country the maximum being upto 85 per cent. Early strength is mainly due to the cement clinker fraction and later strength is that due to the slag fraction. Separate grinding is used as an easy means of verying the slag clinker proportion in the finished cement to meet the market demand. Recently, under Bombay Sewage disposal project at Bandra, they have used 70% ground granulated blast furnace slag (GGBS) and 30% cement for making grout to fill up the trench around precast sewer 3.5 m dia embedded 40 m below MSL.
Portland blast furnace cement is similar to ordinary Portland cement with respect to fineness, setting time, soundness and strength. It is generally recognised that the rate of hardening of Portland blast furnace slag cement in mortar or concrete is somewhat slower than that of ordinary Portland cement during the first 28 days, but thereafter increases, so that at 12 months the strength becomes close to or even exceeds those of Portland cement. The heat of hydration of Portland blast furnace cement is lower than that of ordinary Portland cement. So this cement can be used in mass concrete structures with advantage. However, in cold weather the low heat of hydration of Portland blast furnace cement coupled with moderately low rate of strength development, can lead to frost damage.
The major advantages currently recognised are:
(a ) Reduced heat of hydration;
(b ) Refinement of pore structure;
(c ) Reduced permeability;
(d ) Increased resistance to chemical attack.
(f ) Quick Setting Cement – IS 455: 1989
This cement as the name indicates sets very early. The early setting property is brought out by reducing the gypsum content at the time of clinker grinding. This cement is required to be mixed, placed and compacted very early. It is used mostly in under water construction where pumping is involved. Use of quick setting cement in such conditions reduces the pumping time and makes it economical. Quick setting cement may also find its use in some typical grouting operations.
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