Hydration of Cement and Some special types of Cement

1. HYDRATION OF CEMENT
Presented By,
D.SARATHKUMAR.,B.E.,
(710015813007)
II-Year- M.E-Structural Engineering(Part Time)
Anna University Regional Campus,
Coimbatore-641 046
SPECIAL TYPES OF CEMENT

2. CONTENT
The discussion is divided into following
sections.
Hydration-Introduction
Hydration Process or Mechanism
Heat of Hydration
Factors Affecting Hydration
Special Types of Cement
References

3. HYDRATION- INTRODUCTION
Chemical reaction take place between
cement and water is referred as
hydration.
Hydration is the reaction(Series of
chemical reactions) of cement with
water to form the binding material(C-S-
H Gel).

4. Structure of 1.4 nm tobermorite, a sheet like silicate composed of
octahedral layers and silicate chains. The silica tetrahedra can be
replaced by hydroxil ions. If part the bridging tetrahedra (B) are
replaced only paired groups remain explaining the dimer signal in
NMR studies.
Structure of C-S-H gel

5. Structure of C-S-H gel
x
c
Structural water
Adsorbed water
Capillary pore
C-S-H layer
C-S-H particle
C-S-H gel models

6. HYDRATION- INTRODUCTION
Name of the
Compound
Formula Abbreviated
Formula
Percentage
Tri-calcium
Silicate
3CaO.SiO2 C3S 25-50
Di-calcium
Silicate
2CaO.SiO2 C2S 20-45
Tri-Calcium
Aluminate
3CaO.Al2O3 C3A 5-12
Tetra Calcium
Aluminoferrite
4CaO.Al2O3.Fe2O
3
C4AF 6-12
Bogue’s Compounds

7. HYDRATION- INTRODUCTION
In presence of water, the silicates(C3S and
C2S) and Aluminates(C3A and C4AF) form
products of hydration which in time produce
a firm(Solid) and hard mass - the hydrated
cement paste

8. HYDRATION PROCESS -
CALCIUM SILICATE
(C3S & C2S)

9. HYDRATION PROCESS-C3S
2(3CaO.SiO2)+6H2O 3 CaO.2SiO.3H2O + 3Ca(OH)2
OR
2C3S+6H C3S2H3 + 3Ca(OH)2
 Tri-calcium Silicate hydrates rapidly and forms earlier
strength of the concrete .
 C3S produce more amount heat during hydration process.
 Cement with more content of C3S is better cold weather
concreting.
Calcium Silicate Hydrates

10. SEM micrographs of fractured C3S pastes (w/c = 0.4) in pure water at (A) 7 days, (B)
13 days, (C) 1 month of hydration
HYDRATION PRODUCTS

11. HYDRATION PRODUCTS
Early Porous C-S-H gel (Eternite shingle, 2100x) Late dense C-S-H gel (Eternite shingle, 800x)

12. HYDRATION PROCESS-C2S
2(2CaO.SiO2)+4H2O 3CaO.2SiO.3H2O + 3Ca(OH)2
OR
2C2S+4H C3S2H3 + Ca(OH)2
 Di-calcium Silicate hydrates slowly and it is
responsible for progressive strength of the
concrete.
 C3S produce less amount heat during
hydration process.
 Responsible for major strength of concrete.
Calcium Silicate Hydrates

13.  The other products of hydration of C3S and C2S is
Calcium Hydroxide.
 Lack of durability of concrete, is on account of the
presence of calcium Hydroxide.
 Ca(OH)2 reacts with sulphates presents in soil or
water to form Calcium Sulphate which further
reacts with C3A and causes the deterioration of
concrete. This reaction is known as the sulphate
attack.
HYDRATION PROCESS- CA(OH)2

14. HYDRATION PROCESS- CA(OH)2
 The use of blending materials such as fly
ash ,silica fume& other pozzolanic materials
are steps to over come the sulphate attack.
Pozzolan + Calcium hydroxide+ water
C-S-H (Gel)
 Only advantage is that Ca(OH)2,being alkaline
in nature maintain pH value around 13 in the
concrete which resists the corrosion of
reinforcements.

15. HYDRATION PROCESS-
CALCIUM ALUMINATE HYDRATES
(C3A&C4AF)

16. HYDRATION PROCESS-C3A
3CaO.Al2O3+H2O 3CaO.Al2O3.6H2O
OR
C3A + H C3AH6
 Tri-calcium Aluminate hydrates rapidly about 225o C.
 C3A produce large amount heat during hydration process.
 Hydrated aluminates do not contributes anything to the
strength of concrete, but it will be give durability of concrete.
Calcium Aluminate Hydrates

17. HYDRATION PROCESS-C4AF
4CaO.Al2O3.Fe2O3+H2O 3CaO.Al2O3.6H2O
+CaO.Fe2O3.H2O
C4AF + H
OR
C3AH6
The hydrates of C4AF show a
comparatively higher resistance
to the attack of sulphates.

18. HYDRATION PRODUCTS
Lathshaped AFm (sulfatefree) crystals (3900x) Ettringite (sulfatefree) crystals (1500x)
Hydrogarnets (1500x)
All images are from fiber concrete
samples.

19. w/c is 0.5 for (a)
a is 1.0 for (b)
Volume relationships

20. Hydration mechanisms
in Portland cement

21. Hydration mechanisms
in Portland cement

22. HEAT HYDRATION
 The Hydration of cement with water is
exothermic.
 Exothermic-An exothermic reaction is
a chemical reaction that releases by
light or heat.
 The liberation of heat is called heat of
hydration.

23. HEAT HYDRATION
 Study and control of hydration becomes important
in mass construction(like dams.etc.,)
 Heat evolution due to the reaction of solution of
aluminates(C3S) and sulphates.(C3A)
 Initial heat evolution ceases quickly when the
solubility of aluminates is depressed by gypsum.
 The next heat evolution is on account of formation
of ettringite and reaction of C3S.
 Ettringite-Calcium Aluminate tri-sulphate
Hydrates(C6AS3H32).

24. HEAT EVOLUTION DURING PORTLAND CEMENT HYDRATION
I
II
III
time (hours)
heatevolutionrateW/kg
Induction (dormant) period
0 10 20 30
preinduction period
acceleration period

25. TEMPORAL EVOLUTION OF THE PRODUCTS
Temporal evolution of the hydration hydration products (Kurtis, )

26. HEAT EVOLUTION AND HYDRATION REACTIONS I
C3A hydration
Formation of ettringite
Ettringite coating
retards further
aluminate hydration
Ettringite to monosulfate
transformation and further
aluminate hydration
Relationship between reactions and heat evolution

27. FACTORS AFFECTING HYDRATION
Chemical Composition of Cement
Cement Type
Sulfate Content
Fineness of Cement
Water Cement Ratio
Curing Temperature
Effect of Admixtures

28. SPECIAL TYPES OF CEMENT
Acid Resistance Cement
Blast Furnace Cement
Expanding Cement
Coloured Cement
High Alumina Cement
Hydrophobic Cement
Low Heat Cement
Oil Well Cement
IRS-T 40 Special Cement

29. ACID RESISTANCE CEMENT
 This Cement composed as following,
1.Acid-Resistance Aggregate – Ex: Quartz
2.Additive- Ex: Sodium Fluosilicate
(Na2 SiF6)
3.Aqueous Solution of sodium silicate or
soluble glass.
 Na2 SiF6 - Accelerates the hardening and
increase the resistance of cement to acid.
 Binding Material of acid resistance cement is
soluble glass.

30. BLAST FURNACE CEMENT
 For this cement Slag obtained from blast
furnace is used.
 The slag is waste product in the
manufacturing process of pig iron and it
contains.
 It contains alumina, lime and silica.
 This cement more or less same as Ordinary
Portland Cement.
 Its strength in early days is less and hence
is requires longer curing period.

31. EXPANDING CEMENT
 This cement produced by adding an expanding
medium like Sulpo-aluminate.
 About 8-20 parts of the Sulpo-aluminate clinker
are mixed with 100 parts of Portland cement
and 15 parts of stabilizer.
 Use of expanding cement requires skill and
experience.
 This cement used in Water retaining Structures
and repairing damaged concrete surface.

32. COLOURED CEMENT
 Coloured cement will be obtained by mixing of
pigments with ordinary Portland cement.
 The amount of coloring material may vary from 5 to
10 %.
 If this percentage exceeds 10 % the strength of
cement is affected.
SI .No Pigment Colour
1 Chromium Oxide Green
2 Cobalt Imparts Blue
3 Iron Oxide in different
proportion
Brown, Red, Yellow
4 Manganese Dioxide Black or Brown
oColoured cement are widely used Finishing Interior
exterior, Flooring and artificial marble.

33. HIGH ALUMINA CEMENT
 This cement produced by grinding clinkers formed
by bauxite and lime. The bauxite is an aluminum
Oxide(Al2O3).
 In this cement alumina content should not less then
32%.
 Ratio of weight of alumina to the lime should not be
between 0.85 to 1.30.
 It can stand high temperature.
 It sets quickly and attains higher ultimate strength
short period.
 It is not suitable for mass construction as it evolves
great heat.

34. HYDROPHOBIC CEMENT
 This type of cement contains admixtures which
decrease the wetting ability of cement grains.
 The usual hydrophobic admixtures are acidol,
naphthenesoap, oxidized petrolatum, Oletic acid
and Stearic acid.
 Above substance formed water repellent film
around each cement grains.
 This film protects them form the bad effect of
moisture during storage and transportation.
 The film is broken out when the cement and
aggregate are mixed together at the mixer exposing
the cement particles to normal hydration.

35. LOW HEAT CEMENT
 Formation of cracks in large body of concrete due
to heat of hydration.
 So, concrete technologists produce a kind of
cement which produces less heat during hydration
process.
 This cement will be used in mass construction.
 Low heat evolution is achieved by reducing the
contents of C3S C3A.
SI.
No
Days Heat produced by low
heat cement (cal/gm)
Heat produced by
OPC (cal/gm)
Cal-Calories
1 Calories =
4.2 joules1 7 Not more than 65 89-90
2 28 Not more than 75 90-100

36. OIL WELL CEMENT
 Oil well are drilled through sedimentary rocks
through a great depth of in search of oil.
 That oil or gas may escape through the space b/w
steel casing and rock formation.
 This cement may resist corrosive condition from
sulphur gases or water contains dissolved salts.
 It will be used in 175oC temperature and 1300
kg/m2 pressure.
 This cement obtained in two ways:
i. Adjust cement compounds or adding Retarders.
ii. Adding workability agents.

37. IRS-T 40 SPECIAL CEMENT
 This cement is manufactured as per
specification laid down by ministry of
Railways under IRS-T40: 1985.
 It is Very fine cement with high C3S content
for high early strength.
 It will be used to manufacture of concrete
sleepers for Indian Railways.
 This cement also used in prestressed
concrete elements, high rise buildings, high
strength concrete.

38. REFERENCES
 M S Shetty, Concrete Technology Theory and Practice, S
Chand & Company Pvt Ltd,2011.
 Dr M L Gambir, Concrete Technology Theory and Practice,
Tata McGraw Hill Education Pvt Ltd, 2015.
 P Kumar Mehta, Paulo J M Monteiro, Concrete Micro
Structures, Properties and Materials, Tata McGraw Hill
Education Pvt Ltd, 2008.
 S C Rangwala, Engineering Materials(Material Science),
Charotar Publishing House Pvt Ltd, 2009.
 PPT from, Hydration of Cement, Institut de Mineralogie et
Petrographiem University de Fribourg.
 Dr.Abbas Oda Dawood, Concrete Technology, Lecture
Notes, Department of Civil Engineering-Misan
University.