Type & Grades Of Cement

And What A Consumer Should Know About Cement

Object : • To describe various grades and different types of cement. • To understand a Typical Cement Plant Layout. • Provide information on the properties to enable a consumer to make a proper choice of cement.

Introduction: Cement was invented in 1824 in England by Mr. Joseph Aspidin. Manufacturing first started in England in 1824 and in india in 1904. Cement is freely available in the market under different brand names. Varieties of cement are nowadays available in the market. Our country is the fifth largest producer of cement in the world. Cost of cement is about 12- 15% of the total construction cost. The term “Cement” to an average means only “Portland Cement”. Bulk of Portland cement produced in India today is of normal type. Properties - Excellent binding material, easily workable, good plasticity, hardens ealry , imparts strength to masonry.

I. Cement Preparation

Silicaious Material (Containing Silica) SiO2 19 to 24%

Calcareous Material(Lime) Cao 59 to 64%

Burning in Kiln At 1450deg C

Clinker Clinker Cooled & Ground To Required Fineness Cement

Argillaceous Material (Containing Alumina) Al2O3 3–6%

Fe2O3, SO3, Mgo, Alkalis ( Minor %)

II. Chemical Composition Of Cement : Cemen t

Tricalcium silicate C3S 30-50%

Dicalcium Silicate C2S 20 –45%

Tricalcium Aluminate C3A 8-12%

Tetra Calcium Alumino Ferrite C4AF 6 –10%

III Addition Of Water- Chemical Process Process of change of a compound of cement into others

Hydrolysis

Cement + Water Hydration

Fine Grinding

Process of combination of cement with water

Increases Hydration & Hydrolysis

Setting & Hardening

Result In Early Development Of Strength.

IV

Varieties Of Cement

A.

Ordinary Portland Cement

33 grade – General Construction like plastering, finishing works etc, where high strength is not required. 43 grade – Useful for structural works, precast items etc, Strength development is faster than 33 grade. 53 grade – Used for multistory buikdings, precast prestressed items, bridges, tall structures. Develops very fast strength and speeds up construction.

Table – 1 Physical Property

33 Grade OPC

43 Grade OPC

53 Grade OPC

Relevant IS

IS:269

IS:8112

IS:12269

3 Days Strength 16 Mpa

23Mpa

27Mpa

7 Days Strength 22Mpa

33Mpa

37Mpa

28 Days Strength

33Mpa

43Mpa

53Mpa

Fineness

225 Sq.m/Kg

225Sq.m /Kg

225Sq.m/Kg



Portland Pozzolana Cement : Produced by grinding cement clinker with pozzolana with addition of gypsum. Produces less heat of hydration. Useful for mass concreting. Slow in gaining strength.

•

Portland Blast Furnace Slag Cement : Has low heat of hydration and is relatively better resistant to water containing sulphates acidic environment. D. Hydrophobic Cement : Clinker + Water repllent additive.

soil and

E. White Cement – Meant for architectural works not for structural use. China clay used with limestone, made from raw materials containing very little iron and manganese oxide. F. Sulphate Resistant Cement – Possible with low C3A, High purity Gypsum G. Oil Well Cement: Used in oil wells, develops full strength in a short time. H. Other Cements : Masonry cement, High Alumina Cement, Super Sulphate Cements, Expansive cements etc.

V.

What A Consumer Should Know

Cement Bag should bear BIS Certification mark. Grade of Cement – Means minimum compressive strength of cement sand mortar cube at 28 days strength when tested as per IS standards. Grade of concrete is an important criteria but not the sole criteria to decide the quality of construction. Durability of construction is the important factor. Important factors contributing to the durability are: Type of cement Design Of concrete mix Placing compaction and curing of concrete Subsequent maintenance and repairs. Test Certificate from the supplier

Compressive Strength: Capacity to bear loads, higher strength is preferred.

Soundness – Indicates % expansion due to free lime & magnesia. Excessive expansion reduces durability of structure. The cement with lower value is preferred.

Insoluble residue in cement Non reactive substances in cement. IS specifies a limit of 2 to 4%. Excess indicates adulteration Ideal Color Of CEMENT – A good quality cement is greenish grey.

Chloride content & Alkali percentage The upper limit prescribed by IS for chlorides is 0.05% and alkalies is 0.6%. To control corrosion of steel a good quality of cement should have lower values.

Important Properties Of Cement that affect the durability of structures :

Markings on the bag - Type, Grade, ISI Mark, Licence No. , Week of packing. A cement more than 90 days old from the date of packing is required to be retested before use as per IS code requirement.

Loss on ignition – IS pecifies 4 to 5% limit. Excess percentage indicates adulteration. Check For Adulteration – Cement gives a cool feeling when hand is inserted in the bag. OPC when dropped in a bucket of water it settles down and no floating material is left on the surface.

Conclusion: Different types of cement for different applications – Desirable to construct foundations, sewage and water works in Sulphate resistant cements, RCC in 43 or 53 OPC, Plastering and masonry work in PPC. It will optimize the cost and improve the quality of construction.

Thank you