SANT TUKARAM POLYTECHNIC ,

INDORI .

SEMINAR REPORT ON CEMENT

Prepared By :

ONKAR KADAM (roll no. 307)

Civil Engineering Department

CEMENT :

A cement is a binder, a substance used in construction that sets and hardens and can bind other materials together. The most important types of cement are used as a component in the production of mortar in masonry, and of concrete, which is a combination of cement and an aggregate to form a strong building material.

Cements used in construction can be characterized as being either hydraulic or non-hydraulic, depending upon the ability of the cement to set in the presence of water.

Throughout history, cementing materials have played a vital role and were used widely in the ancient world. The Egyptians used calcined gypsum as a cement and the Greeks and Romans used lime made by heating limestone and added sand to make mortar, with coarser stones for concrete.

The Romans found that a cement could be made which set under water and this was used for the construction of harbours. This cement was made by adding crushed volcanic ash to lime and was later called a "pozzolanic" cement, named after the village of Pozzuoli near Vesuvius.

In places where volcanic ash was scarce, such as Britain, crushed brick or tile was used instead. The Romans were therefore probably the first to manipulate systematically the properties of cementitious materials for specific applications and situations

TYPES OF CEMENTS :

Types of Cement Composition Purpose

Rapid Hardening Cement Increased Lime content

Attains high strength in early days it is used in concrete where form work are removed at an early stage.

Quick setting cement

Small percentage of aluminium sulphate as an accelerator and reducing percentage of Gypsum with fine grinding

Used in works is to be completed in very short period and concreting in static and running water

Low Heat Cement Manufactured by reducing tri-calcium aluminate

It is used in massive concrete construction like gravity dams

Sulphates resisting Cement

It is prepared by maintaining the percentage of tricalcium aluminate below 6% which increases power against sulphates

It is used in construction exposed to severe sulphate action by water and soil in places like canals linings, culverts, retaining walls, siphons etc.,

Blast Furnace Slag Cement

It is obtained by grinding the clinkers with about 60% slag and resembles more or less in properties of Portland cement

It can used for works economic considerations is predominant.

High Alumina Cement

It is obtained by melting mixture of bauxite and lime and grinding with the clinker it is rapid hardening cement with initial and final setting time of about 3.5 and 5 hours respectively

It is used in works where concrete is subjected to high temperatures, frost, and acidic action.

White CementIt is prepared from raw materials free from Iron oxide.

It is more costly and is used for architectural purposes such as pre-cast curtain wall and facing panels, terrazzo surface etc.,

Coloured cementIt is produced by mixing mineral pigments with ordinary cement.

They are widely used for decorative works in floors

Pozzolanic CementIt is prepared by grinding pozzolanic clinker with Portland cement

It is used in marine structures, sewage works, sewage works and for laying concrete under water such as bridges, piers, dams etc.,

Air Entraining Cement

It is produced by adding indigenous air entraining agents such as resins, glues, sodium salts of Sulphates etc during the grinding of clinker.

This type of cement is specially suited to improve the workability with smaller water cement ratio and to improve frost resistance of concrete.

Hydrographic cement

It is prepared by mixing water repelling chemicals

This cement has high workability and strength

GRADES OF CEMENT:

33 Grade Ordinary Portland CementThis ordinary 'Portland' cement is used maximum in the country. It is more suitable cement for masonry and general concrete works where the members are not taken to very high stresses. It is not suitable where ‘Sulphate’ is in the soil or in the ground water.

 43 Grade Ordinary Portland Cement43 grades of cement are used where high early strength in 1 to 28 days range is required. These days the ‘Structural Engineers’ propose these cements mainly for RCC works where a member takes high tensile stress.  53 Grade Ordinary Portland Cement53 grades of cement are used where high early strength in 1 to 28 days range is required. These days ‘Structural Engineers’ propose these cements mainly for RCC works, where a member takes high tensile stress. 

PROPERTIES OF CEMENT :

It is always desirable to use the best cement in constructions. Therefore, the properties of a good cement must be investigated. Although desirable cement properties may vary depending on the type of construction, generally a good cement possesses following properties (which depend upon its chemical composition, thoroughness of burning and fineness of grinding).

Provides strength to masonry. Stiffens or hardens early. Possesses good plasticity. An excellent building material. Easily workable. Good moisture-resistant.

Proper field tests and laboratory tests should be done to ensure the qualities of the cement.

USES OF CEMENT :

Cement is a very useful binding material in construction. The applications of cementover various fields of construction have made it a very important civil engineeringmaterial. Some of the numerous functions of cement are given below.

1. It is used in mortar for plastering, masonry work, pointing, etc.2. It is used for making joints for drains and pipes.3. It is used for water tightness of structure.4. It is used in concrete for laying floors, roofs and constructing lintels, beams,

stairs, pillars etc.5. It is used where hard surface is required for the protection of exposed surfaces of

structures against the destructive agents of the weather and certain organic or inorganic chemicals.

6. It is used for precast pipes manufacturing, piles, fencing posts etc.7. It is used in the construction of important engineering structures such as bridges,

culverts, dams, tunnels, light houses etc.8. It is used in the preparation of foundations, water tight floors, footpaths etc.

COMPOSITION OF CEMENT :

The materials, without the gypsum, are proportioned to produce a mixture with the desired chemical composition and then ground and blended by one of two processes - dry process or wet process. The materials are then fed through a kiln at 2,600º F to produce grayish-black pellets known as clinker. The alumina and iron act as fluxing agents which lower the melting point of silica from 3,000 to 2600º F. After this stage, the clinker is cooled, pulverized and gypsum added to regulate setting time..

Compound Formula Shorthand form

Calcium oxide (lime) Ca0 C

Silicon dioxide (silica) SiO2 S

Aluminum oxide (alumina) Al2O3 A

Iron oxide Fe2O3 F

Water H2O H

Sulfate SO3 S

HYDRATION OF CEMENT :The water causes the hardening of concrete through a process called hydration. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products. Hydration energy (also hydration enthalpy) is a term for energy released upon attachment of water molecules to ions. It is a special case of dissolution energy, with the solvent being water.

BOGUE’S COMPOUND :when water is added to cement it react with the ingredients of the cement chemically & results in the formation of complex chemical compounds terms as BOGUES compounds. which are not for simultaneously.

MANUFACTURING OF CEMENT :

There are two methods of manufacturing cement :

1) dry process , 2) wet process .

1) Dry process :

2) Wet process :

TESTS ON CEMENT :

1). FINENESS TEST : (sieve analysis )i) Weigh approximately 10g of cement to the nearest 0.01g and place it on the sieve.ii) Agitate the sieve by swirling, planetary and linear movements, until no more fine material passes through it.iii) Weigh the residue and express its mass as a percentage R1,of the quantity first placed on the sieve to the nearest 0.1 percent.iv) Gently brush all the fine material off the base of the sieve.v) Repeat the whole procedure using a fresh 10g sample to obtain R2. Then calculate R as the mean of R1 and R2 as a percentage, expressed to the nearest 0.1 percent. When the results differ by more than 1 percent absolute, carry out a third sieving and calculate the mean of the three values.

2) STANDARD CONSISTENCY TEST :

1. Take 400 g of cement and place it in the enameled tray.2. Mix about 25% water by weight of dry cement thoroughly to get a cement paste.

Total time taken to obtain thoroughly mixed water cement paste i.e. “Gauging time” should not be more than 3 to 5 minutes.

3. Fill the vicatmould, resting upon a glass plate, with this cement paste.4. After filling the mould completely, smoothen the surface of the paste, making it level

with top of the mould.5. Place the whole assembly(i.e. mould + cement paste + glass plate) under the rod

bearing plunger.6. Lower the plunger gently so as to touch the surface of the test block and quickly

release the plunger allowing it to sink into the paste.7. Measure the depth of penetration and record it.8. Prepare trial pastes with varying percentages of water content and follow the steps

(2 to 7) as described above, until the depth of penetration becomes 33 to 35 mm.

3_) SETTING TIME TEST :

INITIAL SETTING TIME :

1. Place the test block confined in the mould and resting on the non-porous plate, under the rod bearing the needle.

2. Lower the needle gently until it comes in contact with the surface of test block and quick release, allowing it to penetrate into the test block.

3. In the beginning the needle completely pierces the test block. Repeat this procedure i.e. quickly releasing the needle after every 2 minutes till the needle fails to pierce the block for about 5 mm measured from the bottom of the mould. Note this time (t2).

FINAL SETTING TIME :

1. For determining the final setting time, replace the needle of the Vicat’s apparatus by the needle with an annular attachment.

2. The cement is considered finally set when upon applying the final setting needle gently to the surface of the test block; the needle makes an impression thereon, while the attachment fails to do so. Record this time (t3).

4) .SOUNDNESS TEST :

1. Before commencing setting time test, do the consistency test to obtain the water required to give the paste normal consistency (P).

2. Prepare a paste by adding 0.78 times the water required to give a paste of standard consistency (i.e. 0.78P).

3. Lightly oil the Le-chateliermould and place it on a lightly oiled glass sheet.4. Fill the mould with the prepared cement paste. In the process of filling the mould

keep the edge of the mould gently together.5. Cover the mould with another piece of lightly oiled glass sheet, place a small weight

on this covering glass sheet.6. Submerge the whole assembly in water at a temperature of 27 ± 20 C and keep

there for 24 hours.7. Remove the whole assembly from water bath and measure the distance separating

the indicator points to the nearest 0.5 mm (L1).8. Again submerge the whole assembly in water bath and bring the temperature of

water bath to boiling temperature in 25 to 30 minutes. Keep it at boiling temperature for a period of 3 hours.

9. After completion of 3 hours, allow the temperature of the water bath to cool down to room temperature and remove the whole assembly from the water bath.

10. Measure the distance between the two indicator points to the nearest 0.5 mm (L2)

5) CUBE TEST OF CEMENT :

1. Mixing of material for each test cube shall be separately prepared. The quantities of cement,standard sand and water shall be as follows: Cement – 200 gms, Standard sand – 600 gms, water – (p/4+3) % of mass (cement +sand) where P = % of water required to make cement paste of standard consistency.

2 .All ingredients shall be dry mixed for one minute. After that, water is gradually added till paste is formed of uniform colour. Mixing time shall be between 3-4 minutes. If uniform colour of paste is not achieved after mixing more than 4 minutes, fresh mortar shall be prepared.3.Applymould oil on interior surface of mould and place the mould on vibrating table. Immediately after preparing mortar as describe in point 2, place the mortarinside cube moulds. Rod 20 times for approximate 8 sec to ensure full compaction of mortar.4. Further compaction shall be done by using vibrating machine.The period of vibration shall be two minutes at the specified speed of 12 000 ± 4005.After completion of vibration, remove moulds along with base plate and finish the top surface by trowel.

6. Keepmoulds filled with specimen for 24 ± 1 hr in moist environment. Remove samples from mould and immediately submerge in clean water.

7. After curing period is over, remove cubes from water and immediately place in testing machine with side facing upwards. Cubes shall be tested with out packing between steel plattens of the testing machine and cubes surface.Load shall be steadily and uniformly applied, starting from zero at a rate of 35 N/mm2/min. till failure of sample.8. Calculate compressive strength of specimen by using following formulacompressive strength = P / Awhere

P = Maximum load applied

A =  cross-sectional area of test specimen

Compressive strength shall  be calculated as average value of three samples. If value of individual sample is differing more than 10 % of average value, then that value shall not be considered. In that case average of other two samples shall be considered for compressive strength calculation.

Precautions while Storing Cement :

01. Moisture : It is found that cement will maintain its quality if moisture is kept away from cement. Absorption of 1 to 2% of moisture has no significant effect on quality of cement. But if moisture absorption exceeds 5%, the cement becomes totally useless. Hence cement should be stored in such a manner that no moisture or dampness is allowed to reach cement either from the ground, walls or from the environment etc.

02.   Raised floor : Cement bags shall be stacked off the floor on wooden planks in such a way as to keep about 150 mm to 200 mm clear above the floor with an impermeable plastic sheet underneath.

03.   Strictly use no hook : Do not allow hooks to facilitate in storage of cement. Using hooks has been marked as a detrimental practice for handling of bags as it exposes the cement to the open atmosphere which may be damp and misty.

04.   Keep distance from side wall : One important factor to consider while storage is keeping a safe distance from the side walls , ensuring isolation of cement bags from the leaky and damp walls especially if the walls are exposed to the external atmosphere. A space of 600 mm minimum shall be left all-round between the exterior walls and the stacks.

05.   Proper method of stacking : The arrangement should be such that it is convenient both for stacking and removal of cement bags and it also leaves adequate space for movement and inspection of bags for counting purposes etc.In between individual pile a passage of 600 mm should be provided for easy access.

06.   Store cement bag separately : Never store the cement bags with fertilizers or other products, as any contamination can affect the quality and performance of the screed. Different types of cements shall be stacked and stored separately.

07.Removal of cement : Cement should be removed in order of its storage period, i.e. the rule of first in, first out should be followed. Cement bags should be stacked in a manner to facilitate their removal and use in the order in which they are received.

08.Store leftover cement carefully : Always first use left in torn or opened bags. But ideally they should be re-bagged in plastic bags or heavy duty garbage bags and the mouths sealed securely with string or tape.

09.   Monsoon advisory : In monsoon or in situations when it is necessary to store cement for unusually long periods. Therefore the cement stacks should be completely enclosed by 700 gauge (175 micron or 0.175 mm) polyethene sheet or some other water-proofing membrane materials.

CONCLUSION :

It is a binder that can sets and bind other materials together . Invented by joseph aspdin in 1824 in England . It contains : calcium oxide, silica , aluminium oxide ,ferrous and magnesium

oxides . Rapid hardening , high alumina , slag , white , coloured , air entraining , and

waterproof are important types of cement. Most commonly used in building , irrigation , transportation ,and other civil

structures .

THANK YOU ….