Types of Cement: Uses and their properties

 

Types of Cement -

1.      Ordinary Portland Cement (OPC)

2.      Portland Pozzolana Cement (PPC)

3.      Rapid Hardening Cement

4.      Quick setting cement

5.      Low Heat Cement

6.      Sulfates resisting cement

7.      Blast Furnace Slag Cement

8.      High Alumina Cement

9.      White Cement

10.  Colored cement

11.  Air Entraining Cement

12.  Expansive cement

13.  Hydrographic cement

Fig: Different types of cements

1. Ordinary Portland Cement (OPC) -

Ordinary Portland cement is also called Portland cement because on hardening and its colour resembles to rocks near Portland in England. It was first of all introduced in 1824 by Joseph Asp din, England.

Ordinary Portland cement is the most extensively manufactured and used cement worldwide, which is suited for all types of concrete construction. It is made of Calcareous materials containing calcium carbonate (limestone, marl) and Argillaceous materials containing clay (clay, shale). Main constituents of OPC are lime (62-67%), silica (17-25%), alumina (3-8%), calcium sulphate (3-4%), iron oxide (3-4%) and magnesia (1-3%).

When cement ingredients are inter-grinded and burned, they fuse together, forming complex compounds known as Bogues compounds. In addition to water, these compounds react with it causing the cement to set and harden. These compounds are listed below –

Tricalcium Aluminate(C3A) – It is responsible for the flash setting of cement, i.e., it is the first to harden and set.

Tricalcium Silicate(C3S) – It is responsible for the development of strength in the early stages.

Dicalcium Silicate(C2S) – It is responsible for the progressive strength of cement in later stages.

Tetra Calcium Alumino Ferrate(C4AF) – It does not impart any property in the cement and hence, is of no engineering significance.

Types of Ordinary Portland Cement – 33 grade, 43 grade, and 53 grade. The grade signifies the compressive strength of cement at 28 days.

Grade 33 uses M20 grade concrete and is used for plastering. Grade 43 is applied for precast, plastering, and flooring. It uses M30 concrete. Grade 53 applies a higher concrete grade and is utilized for building roads, bridges, and multi-storeyed buildings, among others.

Properties – OPC resists cracking and dry shrinkage well but is less resistant to chemical attack. Some of the important properties of OPC are:

Specific Gravity – 3.15

Density – 1440 kg/m3

Setting time – Initial setting time should not be less than 30 minutes whereas the final setting time should not be more than 10 hours.

Fineness – As measured by Blaine’s method, the specific surface area should not be less than 225 m2/kg.

In usual construction work, Ordinary Portland Cement is widely used.

Uses of Ordinary Portland Cement:

• It is used for general construction purposes.
• It is also used in most of the masonry works.
• Ordinary Portland cement is also used to manufacture grout, wall putty, solid concrete blocks, AAC blocks, and different types of cement.

 

2. Portland Pozzolana Cement (PPC) -

Portland Pozzolana Cement (PPC) is a blended cement that has three constituents: pozzolanic cement, gypsum, and clink. The percentage of pozzolanic material used in the preparation should be between 10 to 30. If the percentage is exceeded, the strength of cement is reduced.

Pozzolans are natural or synthetic materials that contain silica in reactive forms. It reacts with calcium hydroxide generated by hydrating cement to form additional cementations materials when it is finely divided.

Pozzolanic Materials (Fly ash, volcanic ash, and Calcined clay or silica fumes.)

Uses of Portland Pozzolana Cement:

• PPC is usually used in hydraulic structures, marine structures, construction near the seashore, dam construction, etc.
• It is also used in pre-stressed and post-tensioned concrete members.
• As it gives a better surface finish, it is used in decorative and art structures.
• It is also used in the manufacture of precast sewage pipes.

3. Rapid Hardening Cement -

It is also known as early gain strength cement. Rapid hardening cement is a special type of cement that achieves high strength in less time.

When finely grounded Tri-calcium silicate (C3S) is present in OPC with higher content, it gains strength more quickly than OPC. This type of OPC is called Rapid Hardening Cement. It’s initial Setting Time 30 minutes and Final Setting Time 600 minutes/10 hrs.

Uses of Rapid Hardening Cement :

• Rapid hardening cement is mostly used where rapid construction is needed like the construction of pavement.
• It is used where formwork has to be removed as early as possible in order to reuse it.
• It is used where high early strength is required.
• It is used in industries which manufacture concrete products like slabs, posts, electric poles, block fence, etc. because moulds can be released quickly.
• It is used for cold weather concreting because rapid evolution of heat during hydration protects the concrete against freezing.

4. Quick setting cement -

It is Also known as fast setting cement, Quick setting cement is a special variant of Portland cement. It is prepared using gypsum, aluminium sulphate, and Portland clinker in a pre-determined ratio. The high setting speed of the cement is due to the presence of aluminium sulphate that accelerates the hydration process.

The setting action of cement starts within 5 minutes after addition of water and it becomes hard like stone in less than 30 minutes.

The extreme care is to be taken when this cement is used as mixing and placing of concrete are to be completed in a very short period. This cement is used to lay concrete under static water or running water.

 

5. Low Heat Cement -

It is a spatial type of cement which produces low heat of hydration during the setting. Some chemical composition of Ordinary Portland Cement is modified to reduce the heat of hydration. The chemical composition of low heat cement:

A low percentage (5%) of tricalcium aluminate (C3A)

A higher percentage (46%) of declaiming silicate (C2S).

This cement possesses less compressive strength. The initial Setting Time is about one hour and Final Setting Time is about 10 hours.

Uses of Low Heat Cement :

• It is used for the construction of dam’s large footing, large raft slabs, and wind turbine plinths.
• It is also used for the construction of chemical plants.

 

6. Sulphate Resisting Cement -

Sulphate resisting cement is used to resist sulphate attacks in concrete. Due to the lower percentage(below 5%) of Tricalcium aluminate, the production of calcium sulpho-aluminates gets reduced and it results in the increase in resisting power against sulphate attack.

Uses of Sulphates resisting Cement :

• Construction in contact with soils or groundwater having more than 0.2% or 0.3 % g/l sulfate salts respectively.
• Concrete surfaces subjected to alternate wetting and drying such as bridge piers, concrete surface in the tidal zone, apron, Building near the seacoast.
• Effluent treatment plans, Chimney, Chemical industries, water storage, sumps, drainage works, Cooling towers, Coastal protective works such as sea walls, breakwaters, tetrapods, etc.
• In marine construction

 

7. Blast Furnace Cement -

Portland cement clinker and granulated blast furnace slag are intergraded to make blast furnace cement. The slag is a waste product in the manufacturing process of pig-iron. A maximum of 65 percent of the mixture could be comprised of blast furnace slag. Its strength in early days is less and hence it requires longer curing period. This cement cement is durable, but not suitable for use in dry arid zones.

Uses of Blast Furnace Cement :

• It is highly sulfate resistant
• Frequently used in seawater construction.

 

8. High Alumina Cement -

High Alumina cement is obtained by mixing calcining bauxite (it’s an aluminum ore) and ordinary lime with clinker during the manufacture of OPC. In which the total amount of alumina content should not be lesser than 32% and it should maintain the ratio by weight of alumina to the lime between 0.85 to 1.30. the initial setting time of this cement is about 3.5 hours and final setting time is about 5 hours. It sets quickly and attains higher ultimate strength in a short period. Its strength after 1 day is about 40 N/mm²  and that after 3 days is about 50 N/mm².

Uses of High Alumina Cement :

• It is used where concrete structures are subjected to high temperatures like workshops, refractory, foundries, etc.
• It also used where the concrete is subjected to frost and acidic action.

 

9. White Cement -

White cement is quite similar to Ordinary Portland Cement except for color. Amounts of iron oxide and manganese oxide are low in White Cement. It is expensive then OPC so not economical for ordinary work. It should not set earlier than 30 minutes. It should be carefully transported and stored in closed containers only.

 

Uses of White Cement :

• It is usually used in decorative work.
• It can also use for traffic barriers, tile grouts, swimming pools, roof tiles patching materials, and terrazzo surfaces.

 

10. Colored Cement -

It is produced by mixing 5-10% mineral pigments with Ordinary Cement. Types of pigments are selected according to the desired color.

Uses of Colored Cement : 

Colored cement is used for different decorative work.

 

11. Air Entraining Cement -

It is seen that entrainment of air or formation of gas bubbles while applying cement increases resistance to frost action, fire, scaling, and other similar defects. Air-entraining cement is a special type of cement which entrains (प्रवेश) tinny air bubbles in concrete.

It is produced by grinding minute air entertaining materials with clinker by adding some resinous(राल) materials e.g. vinsol resin to ordinary portland cement.

When the water in concrete gets frizzed due to low temperature, it expands. When air-entraining cement, the air voids in concrete provides space for water to expand without cracking concrete. But this type of cement does not provide high strength in concrete.

Uses of Air-Entraining Cement :

• Especially it is used in areas where the temperature is very low.
• It also resists the Sulphet attack.
• It is used where the de-icing chemical is used.

 

12. Expansive Cement -

In the hydration process, the expansive cement expands its volume. It can be possible to overcome shrinkage loss by using expansive cement.

Uses of Expansive cement :

• It is used in the construction of the pre-stressed concrete component.
• It is also used for sealing joints and grouting anchor bolt.
• In the construction of different hydraulic structures, this type of cement is used.

13. Hydrophobic Cement -

To resist the hydration process in the transportation or storage stage, clinkers are ground with water repellent film substance such as Oleic Acid or Stearic Acid.  These chemicals form a layer on the cement particle and do not allow water to mix and start the hydration process. When cement and aggregate are thoroughly mixed in the mixer, protective layers break and start normal hydration with some air-entrainment which increases workability. It has the property of repelling water and is unaffected during mansoon or rains.

Uses of Hydrophobic Cement :

• Usually, it is used in the construction of water structures such as dams, spillways, or other submerged structures.
• It is also used in the construction of underground structures like tunnel etc.