7 Ingredients and Composition of Cement and Test

Cement ingredients, composition and Test on cement

Cement is one of most important construction material, because it provide strength and durability to the structure, so Right choice of it is greatly affect the structure quality and life.

Cement can be define as fine powdery form of mineral. When it mix with water, hydration of it is occure and it get start gaining strength. 

Before proceed ahead, We should know difference between below terms.

What is Ingredient and Composition of cement?

Ingredient means raw materials use in manufacturing of cement. Strength and setting time of cement is greatly affected by this, so proper quantity of each raw material is require.

There are enlisted ingredient use in manufacturing of cement.

• Lime
• Silica
• Alumina
• Iron Oxide
• Magnesium Oxide
• Sulphur Trioxide
• Alkalies

Composition is nothing but compound form after the chemical process and heating of raw material.

Composition of cement is listed below.

• Tricalcium silicate (C3S)
• Dicalcium silicate (C2S)
• Tricalcium Aluminate (C3A)
• Dicalcium Alumino Ferrite (C2AFe)

Ingredients of Cement and their function:

Proportion of each Ingredient:

Lime :

Lime is one of main and most important ingredient in manufacturing of cement. Cement consist almost 63% of lime. 

it is responsible for strength and soundness of cement. Excess amount of lime makes cement unsound.

Here what is Soundness?

Soundness can be define as gaining strength in Cement within acceptable expansion.

So excess lime cause excess expansion in cement, which cause disintegration of cement.

Silica:

Cement consist 22% of silica. Silica provide strength to cement. It make dicalcium silicate and tricalcium silicate. Surplus amount of silica cause slow setting of cement.

Alumina:

6% of Alumina is use in production of cement. Alumina is responsible for formation of foam in cement. It produce TricalciumAluminate, Dicalcium Alumino Ferrite. This two compositions are responsible for quick setting to cement and development of temperature during hydration.

Iron oxide:

Cement consist 3% iron oxide. Iron oxide deliver colour, hardness and strength to cement. It also very useful during kiln process of manufacturing of cement.

Magnesium oxide:

Cement comprise 2.5% Magnesium oxide. Small amount of Magnesium oxide gives hardness and colour to cement, But excess of it make cement unsound.

Sulphur trioxide:

1.5% of sulphur trioxide present in cement. It's function is almost same as Magnesium oxide, because small quantity of it make cement sound and high cause unsoundness in cement.

Alkalies:

There are 1.5% Alkalies in cement. It should be very less in quantity because it cause efflorescence.

Composition of Cement:

During the kiln process in manufacturing of cement, this chemical composition is produce. Which are in following composition.

Tricalcium silicate:

Cement consists 40% tricalcium silicate in clinker. Tricalcium silicate is responsible for the rapid hardening of cement.

Due to Tricalcium silicate hydration of cement taken place rapidly, so it is responsible for early strength of cement, and due to quick hydration more heat will be generate in cement.

Disadvantage of tricalcium silicate is that due to high hydration heat, there are more chances of development of crack. It consist less resistance against sulphate attack.

Dicalcium silicate:

There are 32% dicalcium silicate in cement clinker. Dicalcium silicate provide ultimate strength to cement. It hydrate at slow pace. It harden slowly, due to it there are less hydration heat.

It consists high resistance against sulphate attack.

Note: up to here, we have understood that tricalcium silicate and dicalcium silicate are responsible for early strength and production of high hydration heat in cement.

By increasing tricalcium silicate and reducing in dicalcium silicate, we can make rapid hardening cement. Which suitable for cementing in cold region

At high percentage of dicalcium silicate and low percentage of tricalcium silicate in cement get harden slowly, less hydration heat, more resistance to sulphate attack.

Tricalcium aluminate:

There are 10.5% tricalcium aluminate in cement. It is first composition in cement to react with water. It is responsible for the initial setting of cement. As it react very fast with water so there are high hydration heat.

Tetra calcium alumino ferrite:

Cement comprise 9% tetra calcium alumino ferrite. It can not react easily with water, so it produce very low hydration heat.

Hint: according to upper both composition we can say that initial setting time of cement is depend upon it. By increase tricalcium aluminate in cement clinker, we can reduce initial setting time of cement.

Tests on cement:

Quality of cement greatly affects on quality of construction, so to decide best quality some tests on it should be conducted.

This test can be divided in two parts. Test conducted in lab and second one on site. In this part we will focus on test conducted in lab in detail.

Tests in Lab

Fineness test:

Cement should be well grind. To check it this test is adopted. Fine cement have more surface area per unit weight and fast gaining of strength. It can be perform two way either sieve method or air permeability method.

Sieve method:

This method is rarely use now a day. In this method cement is sieve through 90 micron sieve by shaking horizontal and vertical direction. For well graded cement residue should not more than 10% by sample weight.

Air Permeability method:

Blaine's apparatus is use for air permeability method. In this method fineness is define in specific surface term. Here specific surface means total surface area per unit weight in gram. It is measure in cm²/ gm.

For good ordinary Portland cement specific surface should be 2250 cm²/ gm.

Consistency Test:

This test is adopted for determination of consistency of cement, initial and final setting time.

To conduct this test vicat's apparatus is use. Plunger of it is 10mm dia and consist 40mm to 50mm length. 

In this test plunger is allow to penetrate through freshly mix cement mortar up to 33mm to 35mm depth at 25°C to 29°C temprature and 20% humidity. This test is conducted for three times.

Consistency of cement can be define as amount of water content, which allow plunger to penetrate in cement mortar at 33mm to 35mm depth within 3 to 5 minute of mixing.

Consistency of cement should be 25% by weight of cement.

Initial setting time:

To decide initial setting time vicat's apparatus is use. In it time require by cement past to penetrate plunger to depth of 33mm to 35mm is counted.

It must be greater than 30 minutes.

Final setting time:

To decide it cement is allow to hard until plunger can not penetrate more than 0.5mm in cement paste. This hardening time is known as final setting time.

Final setting time should not more than 10 hour.

Soundness test: 

We have discussed soundness of cement already. To decide it Le Chatelier apparatus is use. This test is conducted to decide amount of lime and magnesium in cement, because excess amount make cement unsound and cause expansion. 

Expansion of cement should not more than 10mm to avoid cracking and disintegration.

Tensile strength of Cement:

This test is conducted on briquettes in tensile testing machine. Mortar for it is made in 1:3 ratio. Which should be well cured for 3 to 7 days at 25°C tempreture.

Tensile strength of briquettes are measured at 3rd and 7th day after curing. Which are not less than 2 N/mm² after 3 day and 2.5N/mm² after 7 days.

Compression test:

Compression test is carried out on universal testing machine on cement mortar cube of 1:3 proportion.

Total six cube are being tested in it. Three cubes are tested after 3 days of curing and remaining after 7 days of curing.

Compression strength of cement should not less than 11.5 N/mm² after 3 days and 17.5 N/mm² after 7 days.

Field Tests

 Following tests should be adopted on cement on field to check suitability of it for construction.

Manufacturing and expiry date: 

cement lost it's strength with passing of time. It must be use within 90 days of manufacturing.

Colour: 

colour of cement must be evenly light brow.

Presence of Lumps:

Cement bag with lump must be rejected because it indicate reaction of cement with atmospheric water. Lumpy cement resolve less strength.

Rubbed test:

Cement should smooth, when you rubbed it between fingers. If it is not, than it indicate impurity in it.

Floating test:

Cement should float on water for some time before sinking in water.

We will publish more detail blog on tests on cement.

Similar topics:

Types of cement, properties and Use - Construction material

Timber tests,preservation and fire resistance treatments

Timber types, structure and types of defects

Published on CivilEngZone:Think big,We do.

Types of Cement: Properties and use- construction Material

Cement as construction Material : Important Properties|Types and use

What is cement??

Cement can defined as a powdery brown substance, Which get harden after mixing with water due to hydration. 

Cement is generally use as a binder in mortar. Which is made up of calcium,silica and aluminium as primary substance.

Cement is most important construction material, Because it act as binder material in mortar and concrete. It help aggregate and sand to adhere tight to form solid structure.

Important Properties:

Hydration of Cement: 

Hydration is nothing but chemical reaction between water and cement. Whole process can be divided into three stages based on time period.

Setting of Cement:

When we add water in cement it becomes plastic. With passing of time it become solid. This process of converting cement in solid state from plastic state is known as setting of cement.

It can be further divided into two types

Initial setting:

 settlement of cement between mixing and moulding is known as initial hardening. It time frame should be as high as possible to facilitate more time for transporting and casting of it.

Generally as per IS 456, It should me minimum 30 minute

Final setting:

Settlement of cement after placing is known as final settlement. It should occure as early as possible to get early strength to cement.

It should be maximum 10 hour as per IS 456

Hardening of Cement:

After the final settlement cement gain strength. This gaining of strength is known as hardening of cement. This is years long process.

Cement mortar cube

Crushing strength of Cement:

This is nothing but compressive strength of cement mortar after 28 days of curing. This testing cube having 70.71mm wide and surface area 50 cm².

Specific surface of cement:

Surface area of all cement micro particles in 1 gm. It is measure in cm²/gm

Grades of Cement:

According to IS 516-1959, Cement can be divided in three grade based on specific surface.

Grade 33: 2250 cm²/gm

Grade 43: 3400 cm²/gm

Grade 53: 3400 cm²/gm

Note : major differences between grade 43 and 53 are that Grade 53 have more shrinkage and gain early strength in short time period, So it can be use where early strength is require.

Types of Cement and their use:

There are different types of cement, which use in construction. All have different properties,advantages and dis-advantages.

We can use suitable cement based on our requirement,if we know it well.

Lets discuss important types of cement one by one.

Ordinary Portland Cement:

This is most use and common types of cement. Which is also known as OPC.

This cement gets hardening slowly, so less crack and shrinkage occure.

But major disadvantage is that it posses less chemical resisting strength, so it can't be use in soil, which contain high sulphur.

This type of cement is suitable for all types of general construction.

Rapid Hardening Cement:

As per name this type cement gain strength early, so it is also known as Hight Early Strength cement.this early strength is due to high amount of tri calcium silica and low amount of dia calcium silica. Normally this type of cement contain less weight compare to other.

Major advantages of this cement are that it require less period of curing and formwork, so it is economical.

But as It get strength faster, so there are more chances of developing of cracks, so it can't be use for massive concrete work like dam.

This cement should be use, where early strength is require likewise road construction, cold region.

Quick setting cement:

In quick setting cement high amount of alumina is uses, because it is responsible for quick setting of cement

This cement is used, where quick setting of cement is require like running water.

Note: difference between rapid hardening cement and quick setting cement is that however quick setting cement set quickly, but it gain strength at normal as OPC.

Portland pozzolana cement:

Portland pozzolana cement is made by adding 30% pozzolana in ordinary Portland cement.

Pozzolana contain 80% silicious material, mostly clay.

In hydraulic structures like dam and canal, this cement is use.

Low heat Portland cement:

In this type of cement high amount of dia calcium silica is use, which is responsible for rapid hardening and high heat. So there are less production of heat

Due to less amount of tri calcium silica, hardening of cement will be slow, so there are less compression strength. So it should not use for thin structure.

This cement is mostly use in retaining wall.

Sulphate resisting Portland cement:

In Sulphate resisting Portland cement tri calcium aluminate is keep less than 5%. Because of it chemical resistant capacity of cement is get higher.

In alkaline land this kind of cement is use.

This cement is use in canal linings and culverts.

High Alumina cement:

Aluminium is responsible for hardening and strength of cement. This cement contain 35% of alumina. So it settle quickly and get harden fast.

This types of cement is use, where quick hardening is require. In sea water construction, chemical plants and furnaces, this type of cement is use.

Blast furnace slag cement:

By mixing ordinary Portland cement clinker with blast furnace slag, this cement is made. Due to it, it is cheaper as compare to OPC.

This cement develops low heat, so it contain less strength.

This one is mostly use in dams, bridge abutments and retaining wall.

Coloured cement:

This one is also known as colocrete. It is formed by adding 5% to 15% require colouring pigment.

It is mostly use in finishing work, like wise floor,wall and other external surfaces.

White cement rendering work

White cement:

This cement is produce by raw material free from iron oxide, so it is white ordinary Portland cement. It is costly as compare to other cements. 

White cement is mostly use for architectural purpose. Such as a building external and internal rendering, precast Decorative structure,ceiling etc.

Air Entraining Cement:

This cement is made by adding air entraining agent during grinding of cement. Sodium salt and glue are use as air entraining agent.

This cement contain more workability, due to less water cement ratio, so less cement is require for mortar and concrete.

This cement is suitable for cool region  where frist action taken place. 

Hydrophobic cement: 

During production water reppelling chemical is mix. Due to this, it contain high workability and strength.

This cement unaffected by water, so this cement is use for hydraulic structure like dams,retaining wall,spillway etc.

Similar topics:

Cement ingredients and Composition, Tests on cement

Timber structure, Types, Defects, Seasoning: civilengzone

Timber preservation, Fire resistance treatment and Tests: Civilengzone(think big,we do)

Timber-Test,Preservation methods,Fire resistance treatment

Timber as a construction material: Preservation methods|Fire resistance treatment|Tests on Timber

Preservation methods of timber:

Timber is one of the most use construction material, because it posses great characteristics and cheap in price as compare to other materials. But it gets defect easily, so preservation of it is require.

Chemical technique with which we get increase durability,strength and less vulnerable to attack by white ant and other microbe is known as preservation of Timber.

It can sort in seven different class.

Ascu treatment:

Ascu is powdery form preserver, which is made up of Hydrated Arsenic pentoxide (1 part),Blue Vitrol or Copper sulphate(3 parts),Potassium di chromate(4 parts).

6 part of Ascu powder and 100 part of water is mix together to make solution. This solution is sprayed on the timber.

This treatment protect timber against white ant.

Chemical salt:

In this method solution is made up of water,natural salt,Copper sulphate, Mercury Chloride, Sodium Fluoride and Zinc Chloride is applied on timber.

This solution penetrates deep inside a timber, which result in instant increase in weight of timber.

Coal tar

Coal-tar:

This method is also known as tarring method, because in this hot coal-tar is applied in timber with brush.

This method is suitable for rough use timber work like door,window and it's frame. It is also very good for part embedded inside ground.

Creosote oil method:

Creosote oil is produce by distillation of tar. Creosote is sprayed on timber at high pressure and temperature till 2 hour. This spraying process is known as creosoting.

This process increase a resistance against fungus attack, so life of timber is increase. This method is good option for railway sleeper,pile and poles. It should not adopted on interior of building.

Charring method:

Poled are inlay in ground, so it's lower end is vulnerable to insect and fungus attack. In this case its lower end is extinguish into water after charred with water. This preservation process is known as charring method.

Oil paint

Oil paint method:

Oil paint is most commonly use and most easy preservation method for the timber. In it two to three coat of oil paint is applied on the surface of the timber. This surface resist the penetration of water inside a timber body and make it durable.

Solignum method:

It is toxic liquid. In this method, this hot liquid is applied on the timber with brush. As this liquid is toxic in nature, it protect timber from attack of white ant.

Fire resistant treatment for timber.

One of the major disadvantage of timber is poor fire resistant property as compare to other major building material. Specially non-refractory wood. Now question come in your mind, what is non-refractory wood.

According to fire catching property wood can be divided into two way

Refractory wood: 

which hardly vulnerable be catch fire easily.

Eg:sal and teak wood

Non-refractory wood: 

obviously which can catch fire easily.

Eg:chir,deodar,fir(because it contain more oil)

Now, lets come on over point about fire resistant treatment. There are two method for it.

By use of chemicals:

In this treatment chemical call borax or sodium arsenate use. This chemical is apply on timber, which increase the fire resistant of timber and it burn slowly.

This chemicals are known as "Fire Protection

Compounds" or "Anti pyrines".

Sir Abel's process:

This is a most uses process for fire resistant. It adopted in three phase

In first phase, dilutes sodium silicate's coat is apply

In second stage, slaked fat lime is applied.

In third and last stage concentrate sodium silicate is applied.

Different tests on Timber:

There are vareity of timber. Opt out of it is headache. To over come it, there are different kind of test on timber, which decide different characteristics of timber. So out of it we can decide best suitable one for us.

Specific gravity:

Specific gravity of timber should be 1.54. To decide it test should be conducted on 50mm×50mm×150mm timber plank. It's volume,weight and moisture content should be measured.after putting values in following equation, we will get specific gravity of timber.

             G= ( W×V) ×(100/(100+M))

Where, 

G= specific gravity

W =weight

V= volume

M= moisture content

Volumetric shrinkage:

Shrinkage of timber should be least, to make sure it this test is conducted.

Timber's initial volume and weight is measured. Then it is heated in oven around 1030°C tempreture until it reach at constant weight.

Then to decide volumetric shrinkage and moisture content percentage, values put in following equations.

Volumetric shrinkage=(Vi  - Vf) / Vi 

And

Moisture content =(Wi - Wf) / Wi

Where, 

Vi= initial volume

Vf=  final volume

Wi= initial weight

Wf= final weight

Bending test:

If timber is used as a beam of a structure, then it will face extreme tension at center of it, to make sure bending capacity of beam this test is conducted.

To conduct this test 50mm×50mm×100mm timber section consist fiber parallel along it's length is use.

Three point load is applied at two third length of beam at 3mm per minute till the appearance of crack in it. It is calculate based on simple bending equation.

Bending strength of timber should be 40 to 100 Mpa.

Tension test:

In timber beam tension derive at lower section of beam. To determine suitability of timber as beam tension test is conducted.

Test specimen of 10mm×10mm is fitted in UTM (universal testing machine). Tension applied at 2.5mm per minute until occurrence failure.

Tension test is calculated by ratio of maximum tension and cross section of test specimen.

Minimum tension of timber should be 80 to 190 Mpa.

Compression test:

Timber column is loaded under compression. To determine it's capacity, compression  test is adopted.

In it sample logged of size 

50mm×50mm×200mm sized is fitted in UTM( universal testing machine). Timber grain must be perpendicular to compression. Initially 2.5KN compression is applied. Deformation at center length gauge is measured. According to it compression is measured.

Compression of column should be 30 to 80 Mpa at 15% moisture content.

Note: From all observation we show that moisture content greatly affect on performance of timber. Following are some require moisture content for different purpose.

Timber use in structure of building should have moisture content 10% to 20%

Flooring timber should have 7% to 12% moisture content.

Timber of building frame contain 13%  to 20% moisture.

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Timber as construction material-types, structure of wood, defect of timber, quality of good timber visit... by CivilEngZone(Think big,We do)