lecture no. 03 subject: cement types and characteristics of cements characteristics of cements

Lecture No. 03Lecture No. 03

Subject: Subject:

Cement Types andCement Types and

Characteristics of Characteristics of CementsCements

Objectives of Lecture:Objectives of Lecture:

Explain briefly the various types Explain briefly the various types of Portland cement.of Portland cement.

Explain the chemical compounds Explain the chemical compounds

in Portland cement.in Portland cement.

Types of Portland CementTypes of Portland Cement

Different types of Portland Different types of Portland cement are manufactured to cement are manufactured to meet the requirements for meet the requirements for specific purposes.specific purposes.

The American Society for Testing The American Society for Testing and Materials (ASTM) C150 and Materials (ASTM) C150 specifies the following eight specifies the following eight types of Portland cement.types of Portland cement.

Type Type Name Name Type IType I NormalNormal

Type IAType IA Normal, air-entrainingNormal, air-entraining

Type IIType II Moderate sulfate Moderate sulfate resistanceresistance

Type IIAType IIA Moderate sulfate Moderate sulfate resistance, air-resistance, air-

entrainingentraining

Type IIIType III High early strengthHigh early strength

Type IIIAType IIIA High early strength, High early strength, air-entrainingair-entraining

Type IVType IV Low heat of hydrationLow heat of hydration

Type VType V High sulfate High sulfate resistanceresistance

Type I cementType I cement

It is a general-purpose cement used It is a general-purpose cement used in concrete for making pavements, in concrete for making pavements, floors, reinforced concrete buildings, floors, reinforced concrete buildings, bridges, tanks, pipes, etc.bridges, tanks, pipes, etc.

It is for all uses where the special It is for all uses where the special properties of other cement types are properties of other cement types are not required, such as sulfate attack not required, such as sulfate attack from soil and water, or to an from soil and water, or to an objectionable temperature rise.objectionable temperature rise.

Application of Type I CementApplication of Type I Cement

Type II cementType II cement

It is used where precaution against moderate It is used where precaution against moderate sulfate attack is important, as in drainage sulfate attack is important, as in drainage structures, which may be subjected to a structures, which may be subjected to a moderate sulfate concentration from ground moderate sulfate concentration from ground waters. It has moderate sulfate resistance waters. It has moderate sulfate resistance because it contains no more than 8% tricalcium because it contains no more than 8% tricalcium aluminate (Caluminate (C33A).A).

It usually generates less heat of hydration at a It usually generates less heat of hydration at a slower rate than Type I cement and therefore slower rate than Type I cement and therefore can be used in mass structures such as large can be used in mass structures such as large piers, heavy abutments, and retaining walls.piers, heavy abutments, and retaining walls.

Due to less heat generation it can be preferred Due to less heat generation it can be preferred in hot weather.in hot weather.

Application of Type II CementApplication of Type II Cement

Type III cementType III cement

It is chemically and physically similar to It is chemically and physically similar to Type I cement, except that its particles Type I cement, except that its particles have been ground finer.have been ground finer.

It provides high early strengths at an early It provides high early strengths at an early period, usually a week or less.period, usually a week or less.

It is used when forms need to be removed It is used when forms need to be removed as soon as possible or when the structure as soon as possible or when the structure must be put into service quickly.must be put into service quickly.

It is preferred in cold weather for reduction It is preferred in cold weather for reduction in the curing period.in the curing period.

Application of Type III CementApplication of Type III Cement

Type IV cementType IV cement

It is used where the rate and amount of It is used where the rate and amount of heat generated from hydration must be heat generated from hydration must be minimized.minimized.

It develops strength at a slower rate than It develops strength at a slower rate than other cement types.other cement types.

It is most suitably used in massive concrete It is most suitably used in massive concrete structures, such as large gravity dams, structures, such as large gravity dams, where the temperature rise resulting from where the temperature rise resulting from heat generated during hardening and must heat generated during hardening and must be minimized to control the concrete be minimized to control the concrete cracking.cracking.

Application of Type IV CementApplication of Type IV Cement

Type V cementType V cement

It is used only in concrete exposed to It is used only in concrete exposed to severe sulfate action – principally where severe sulfate action – principally where soils or ground waters have a high sulfate soils or ground waters have a high sulfate content.content.

Its high sulfate resistance is due to its low Its high sulfate resistance is due to its low CC33A content of about 4%.A content of about 4%.

It is not resistant to acids and other highly It is not resistant to acids and other highly

corrosive substances.corrosive substances.

Air-Entraining Portland CementsAir-Entraining Portland Cements(Types IA, IIA, and IIIA)(Types IA, IIA, and IIIA)

These cements have same composition as These cements have same composition as Types I, II, and III, respectively, except that Types I, II, and III, respectively, except that small quantities of air-entraining material small quantities of air-entraining material are inter-ground with the clinker during are inter-ground with the clinker during manufacture.manufacture.

These cements produce concrete with These cements produce concrete with minute, well-distributed and separated air minute, well-distributed and separated air bubbles which improve the resistance to bubbles which improve the resistance to freeze-thaw action and to scaling caused by freeze-thaw action and to scaling caused by chemicals applied for snow and ice removal.chemicals applied for snow and ice removal.

White Portland CementWhite Portland Cement

It has composition same as Type I or Type III It has composition same as Type I or Type III cement, except that it has a white color cement, except that it has a white color instead of gray color.instead of gray color.

It is made of selected raw materials It is made of selected raw materials containing negligible amounts of iron and containing negligible amounts of iron and magnesium oxides-the substances that give magnesium oxides-the substances that give cement its gray colors.cement its gray colors.

It is used primarily for architectural It is used primarily for architectural purposes.purposes.

Application of White CementApplication of White Cement

Blended Hydraulic CementsBlended Hydraulic Cements

These cements are produced by These cements are produced by intimately and uniformly intimately and uniformly blending the Portland cement blending the Portland cement and the by-product materials, and the by-product materials, such as blast-furnace slag, fly such as blast-furnace slag, fly ash, silica fume and other ash, silica fume and other pozzolans.pozzolans.

Blended CementsBlended Cements

ASTM C 596 recognizes five classes of ASTM C 596 recognizes five classes of blended cements:blended cements:

Portland blast-furnace slag cement-Portland blast-furnace slag cement-Type IS.Type IS.

Portland pozzolan cement-Type IP Portland pozzolan cement-Type IP and Type P.and Type P.

Pozzolan-modified Portland cement-Pozzolan-modified Portland cement-Type I(PM).Type I(PM).

Slag cement-Type S.Slag cement-Type S. Slag-modified Portland cement-Type Slag-modified Portland cement-Type

I(SM).I(SM).

SPECIAL CEMENTSSPECIAL CEMENTS

Masonry CementsMasonry Cements These cements are used in

mortar for masonry construction.

ASTM C 91 classifies masonry cements as: Type N, Type S, and Type M

Expansive CementsExpansive Cements

These cements are primarily These cements are primarily used in concrete for shrinkage used in concrete for shrinkage control.control.

ASTM C 845 classifies expansive ASTM C 845 classifies expansive cements as:Type E-1(K), Type E-cements as:Type E-1(K), Type E-1(M), Type E-1(S).1(M), Type E-1(S).

Special Cements (Not covered by Special Cements (Not covered by ASTM)ASTM)

TypeType UsesUses

Oil-well cementsOil-well cements For sealing oil For sealing oil wellswells

Waterproof Waterproof Portland cementsPortland cements

For reducing For reducing capillary water capillary water transmissiontransmission

Plastic cementsPlastic cements For making plaster For making plaster and stucco and stucco (coating exterior (coating exterior surfaces)surfaces)

Chemical Compounds in Chemical Compounds in Portland CementPortland Cement

As indicated earlier the burning operation As indicated earlier the burning operation of the raw materials results into the of the raw materials results into the reaction between the oxides and four reaction between the oxides and four compound compositions are formed in the compound compositions are formed in the final cement product, as follows:final cement product, as follows:

CC33S S = = 3CaO.SiO3CaO.SiO22 (Tricalcium silicate) (Tricalcium silicate) CC22SS = = 2CaO.SiO2CaO.SiO22 (Dicalcium (Dicalcium

silicate)silicate) CC33AA = = 3CaO.Al3CaO.Al22OO3 3 (Tricalcium aluminate)(Tricalcium aluminate) CC44AF = 4CaO. AlAF = 4CaO. Al22OO33.Fe.Fe22OO33 (Tetracalcium (Tetracalcium

aluminoferrite)aluminoferrite)

In generalIn general

CC33S S Constitutes 50% to 70% of the clinker.Constitutes 50% to 70% of the clinker.

CC22SS Constitutes 15% to 30% of the Constitutes 15% to 30% of the clinker.clinker.

CC33AA Constitutes 5% to 10% of the Constitutes 5% to 10% of the clinker.clinker.

CC4AF AF Constitutes 5% to 15% of the Constitutes 5% to 15% of the clinker.clinker.

Role of Compound CompositionRole of Compound Composition

1. C3S

Hydrates and hardens rapidly and Hydrates and hardens rapidly and is largely responsible for initial is largely responsible for initial set and early strength.set and early strength.

Early strength of cement is higher Early strength of cement is higher with increased percentages of Cwith increased percentages of C33S.S.

2. C2S

Hydrates and hardens slowly.Hydrates and hardens slowly.

Contributes largely to strength Contributes largely to strength

increase at ages beyond one increase at ages beyond one week.week.

Alite (CAlite (C33S) and Belite (CS) and Belite (C22S) S)

3. C3A

Liberates a large amount of heat during the Liberates a large amount of heat during the first few days of hydration and hardening.first few days of hydration and hardening.

Also contributes slightly to early strength Also contributes slightly to early strength development.development.

Gypsum added to the cement slows down Gypsum added to the cement slows down the hydration rate of Cthe hydration rate of C33A.A.

Cements with low percentages of CCements with low percentages of C33A are A are especially resistant to soils and waters especially resistant to soils and waters containing sulfates.containing sulfates.

C4AF

Does not play any significant Does not play any significant role on hydration.role on hydration.

Hydration of Cement In the presence of water the cement In the presence of water the cement

compounds chemically combined with water compounds chemically combined with water (hydrate) to form new compounds that are (hydrate) to form new compounds that are the infrastructure of the hardened cement the infrastructure of the hardened cement paste in concrete.paste in concrete.

Both CBoth C33S and CS and C22S hydrate to form calcium S hydrate to form calcium hydroxide and calcium silicate hydrate (CSH). hydroxide and calcium silicate hydrate (CSH). Hydrated cement paste contains 15% to 25% Hydrated cement paste contains 15% to 25% Calcium hydroxide and about 50% calcium Calcium hydroxide and about 50% calcium silicate hydrate by mass. The strength and silicate hydrate by mass. The strength and other properties of hydrated cement are due other properties of hydrated cement are due primarily to calcium silicate hydrate.primarily to calcium silicate hydrate.

CC33A reacts with water and A reacts with water and calcium hydroxide to form calcium hydroxide to form tetracalcium aluminate hydrate.tetracalcium aluminate hydrate.

CC44AF reacts with water and AF reacts with water and calcium hydroxide to form calcium hydroxide to form calcium aluminoferrite hydrate.calcium aluminoferrite hydrate.

For all the Portland cement For all the Portland cement compound hydration reactions compound hydration reactions see Table 2-5:see Table 2-5:

Hydration ReactionsHydration Reactions

Chemical composition and Chemical composition and Fineness of CementsFineness of Cements

Relative Reactivity of Cement Relative Reactivity of Cement compoundscompounds

Relative volume of major compounds in Relative volume of major compounds in hydrated cement pastehydrated cement paste