Bogues Compounds | Know 4 Types of Major Components of Cement Quickly

Bogues Compound in Cement are the complex compounds formed when the constituents of cement are subjected at high temperatures to form clinkers.

Why are Major Compound called Bogues Compound?

R. H. Bogue worked and identified the major compounds of cement, hence these are recognised as Bogues compounds.

What are Bogues Compound?

Bogues Compound are listed below:

1. Tricalcium silicate (C₃S)

2. Dicalcium silicate (C₂S)

3. Tricalcium aluminate (C₃A)

4. Tetracalcium aluminoferrite (C₄AF)

Bogues Compounds form a major part of the constituents of cement. The cement consist of major and minor constituents.

The major compounds of cement or Bogues compound and their chemical formulae are tabulated below:

Bogue’s Compound	Formula	Abbreviation	Color	Tornebohm Name
Tricalcium silicate	3 CaO.SiO₂	C₃S	white	alite
Dicalcium silicate	2 CaO.SiO₂	C₂S	white	belite
Tricalcium aluminate	3 CaO.Al₂O₃	C₃A	white/grey	celite
Tetracalcium aluminoferrite	4 CaO. Al₂O₃.Fe₂O₃	C₄AF	black	felite

1. Tricalcium Silicate (C₃S)

Along with C₂S, C₃S is responsible for strength gain in cement. C₃S constitutes about 45% in the cement nowadays.

It is considered the best cementing material, providing early strength to the cement.

Functions of C₃S are:

Ease in grinding the cement clinkers
Enhancing the resistance to freezing and thawing

However, increasing the content of C₃S above a specific limit may greatly increase the heat of
hydration along with increasing the solubility of cement in water.

2. Dicalcium Silicate (C₂S)

C₂S constitutes about 25% in the cement nowadays.

Combinedly, C₃S and C₂S form 80 % constituent of cement.

Functions of C₂S are:

Provides later strength in cement
Enhancing the resistance to chemical attack

However, increasing the content of C2S above a specific limit may render difficulty in grinding of
clinkers, and also decreases early strength as well as the heat of hydration.

3. Tricalcium Aluminate (C₃A)

Functions of C₃A are:

Reacts quickly with water
Flash setting of cement is caused

An increase in C₃A reduces the resistance to sulphate attack as well as the ultimate strength of
cement.

As it is responsible for initial setting, high heat of hydration and induces volumetric changes, it
causes cracking.

4. Tetracalcium Aluminoferrite (C₄AF)

C₄AF has the least cementing value out of all the four compounds and is responsible for the
flash set of cement.

Increasing the content of C₄AF reduces the strength of cement.

Hydration of Bogues Compound

Hydration of cement is an essential for phenomenon for the strength gain, which occurs when water is added to cement. Only Bogues compounds are responsible for the strength of cement.

To know more about the chemistry of hydration of cement, read the Hydration of Cement.

1. Hydration of C₃S

C₃S hydrates in early stages, and hence is responsible for the initial heat of hydration, and also the initial strength gain of the cement.

The rate of reaction of C₃S is more and hence, more heat is liberated as compared to C₂S.

2. Hydration of C₂S

C₂S hydrates later on as its rate of reaction is lower. Hence, it is responsible for the ultimate strength of the cement.

3. Hydration of C₃A and C₄AF

C₃A hydrates very early upon addition of water. Hydration of C₃A can result into flash setting of cement preventing hydration of the silicates.

Calcium sulphate present in the cement clinkers dissolves forming calcium sulphoaluminate, which is insoluble in water. It forms a membrane over C₃A, preventing its further hydration.

The compounds formed because of hydration breaks the preventive membrane over C₃A, and it again becomes available for hydration.

C₃A can be said to catalyse the hydration of C₃S.

The equations for the hydration of the above components are given HERE.

Rate of Hydration of Bogues Compounds

Aluminates hydrate very early, but they do not contribute much to the strength development.

Out of the two silicates, tricalcium silicate hydrates earlier while the hydration of dicalcium silicate occurs very slowly.

Heat of Hydration of Bogues Compounds

The heat of hydration of all the four Bogues Compounds is tabulated below:

Component	Heat of Hydration (in J/g)
C₃S	500 J/g
C₂S	260 J/g
C₃A	865 J/g
C₄AF	420 J/g

Compressive Strength Contributed by Bogues Compounds

Contribution of Bogues Compounds to the
Strength of Cement — Contribution of Bogues Compounds to the Strength of Cement

C₂S and C₃S contribute approximately same strength after a year or so when most of the hydration of C₂S is completed. C₃A gives very less compressive strength while C₄AF does not contribute to compressive strength.

Minor Compounds in Cement

The above four compounds are found as major compounds in cement, but there are minor compounds too like K₂O and Na₂O. The minor compounds do not affect the properties of hydrated cement significantly. However, they play a major role in alkali aggregate reaction, which is a harmful phenomenon.

Tornebohm Nomenclature

There are other scientists too like, Lee Chatlier and Tornebohm, who observed the Bodues compounds in cement clinkers in the form of crystals.

Tornebohm named these crystals, which are recognised by Bogue as follows:

Alite
Belite
Celite
Felite

Equations to Find Percentage of Bogues Compounds from Oxide Constituents Used

These equations are given be R. H. Bogue.

1. $C_{3}S=4.07(CaO)-7.60(SiO_{2})-6.72(Al_{2}O_{3})-1.43(Fe_{2}O_{3})-2.85(SO_{3})$

2. $C_{2}S=2.87(SiO_{2})-0.754(3CaO.SiO_{2})$

3. $C_{3}A=2.65,$

4. $C_{4}AF=3.04,$

Key TakeAway

Bogues Compound form the major component of cement. These compounds of cement were
recognised based on the work of Bogue. Hence, they are also called Bogue’s compounds.

C₃S – Tricalcium silicate
C₂S – Dicalcium silicate
C₃A – Tricalcium aluminate
C₄AF – Tetracalcium aluminoferrite

Major compounds are responsible for the hydration of cement, which leads to strength gain in
cement. Major compounds comprise about 90 % of the total cement compounds.

FAQ

Write the chemical composition of portland cement.

Chemical composition of cement: Tricalcium silicate (C₃S), dicalcium silicate (C₂S),
tricalcium aluminate (C₃A), and tetracalcium aluminoferrite (C₄AF) form over 90 % of the
chemical constituents of cement.

Calcium sulphate (CaSO₄.2H₂O), magnesium oxide (MgO), titanium oxide (TiO₂), manganese oxide (Mn₂O₃), alkalis (K₂O, Na₂O, P₂O₅) are present in minor proportions in cement.

The chemical composition of cement depends on the raw materials used in cement
manufacturing- lime, silica, alumina, and iron oxide.

To know in detail, click Chemical Composition of Cement.