1. Cement-based materials chemistry
Henan polytechnic university
School of Materials science and engineering
Cement-based materials chemistry

2. The relationship between the composition and the phase of cement
Henan polytechnic university
School of Materials science and engineering
The relationship between the composition and the phase of cement

3. §1 Introduction
Advantages of cement
Classification
Summary

4. Introduction Portland cement was developed in the nineteenth century.
It has become one of the most important building materials.
It has complex chemical compositions, but the main cementing compound is calcium silicate hydrate.
Ordinary Portland cement can be modified for high early strength, for sulfate resistance, for low heat production, or for use in masonry.

5. Introduction
For architectural use, it can be formed white, black, or in various colors.
High-alumina cement and magnesium-oxy-chloride cement are different from Portland cement in chemical compositions.

6. Introduction Classification Application General Cement Portland Cement
Ordinary Portland Cement
Portland Blast-Furnance-Slag Cement
Portland Pozzolana Cement
Portland Fly-Ash Cement
Composite Portland Cement

7. Characteristic Cement
Introduction
Classification
Special Cement
Masonry cement
Oil well cement
Characteristic Cement
Quick-hardening cement
Expansive cement
Sulfate resisting cement
Modified cement

8. Sulfoaluminate Cement
Introduction
Classification
Chemical Component
Portland Cement
Common engineering
Aluminous Cement
Sulfoaluminate Cement
Rush- repairing project, earlier strength project, engineering constructing in winter, anti-corrosion and freezing resistance
Earlier strength/Antisulfate/Rush-repairing project/Anchor/ underground engineering

9. Summary
Among many types of cement used in China, Portland Cement accounts for more than90% of the products of cement. We should stress the study of the compound, technical property, and application of Portland Cement in cement learning.

10. §2 Portland Cement Production and Composition of Portland Cement
Hydration, Setting and Hardening of Portland Cement
Technical Properties of Portland Cement
Corrosion and Prevention of Hardened Cement
Characteristics and Application of Portland Cement

11. What is ‘Portland Cement’？
2.1 Production and Composition of Portland Cement
What is ‘Portland Cement’？
Mixing
materials
Gypsum
Raw
Clinker
Portland Cement

12. What is ‘Portland Cement’？
Portland cement is formed by grinding together clay-based and lime-based materials (usually clay and limestone) and is heated to about 1450℃. At 650℃ the limestone separates into CO2 and CaO. When the silica reaches the point of fusion, the atoms are able to move about and the CaO combines with SiO2 and a small amount of Al2O3 and Fe2O3, forming Portland cement clinker.
The clinker is then ground to a fine powder, and a small amount of gypsum is added.

13. Production and Composition of Portland Cement
Limestone
Crushing
1450℃
Clay
Grinding
Raw material
Clinker
PⅠ
Grinding
Gypsum
Iron ore
powder
PⅡ
Mixing
materials
Fig.2.1 Process to Produce Portland Cement

14. Mineral Compounds and Properties
Main Mineral Compounds of Portland Cement Clinker include (in tab.2.1):
Tricalcium silicate
Dicalcium silicate
Tricalcium aluminate
Tetracalcium aluminoferrite
Properties of the compounds are in the tab2.2:

15. Tab.2.1 Mineral Compounds of Portland Cement
Chemical structural formula
Abbreviation
Tricalcium silicate
3CaO·SiO2
C3S
Dicalcium silicate
2CaO·SiO2
C2S
Tricalcium aluminate
3CaO·Al2O3
C3A
Tetracalcium aluminoferrite
4CaO·Al2O3·Fe2O3
C4AF

16. Tab.2.2 Properties of Mineral Compounds
Mineral types
Tricalcium silicate
Dicalcium silicate
Tricalcium aluminates
Tetracalcium aluminoferrite
Abbreviation
C3S
C2S
C3A
C4AF
Content (%)
37-60
15-37
7-15
10-18
Hydration speed
fast
slow
fastest
Hydration heat
much
little
most
more
Strength
high
early low
later high
low
Anti-corrosion
good
fine
poor
excellent
Shrinkage
middle
better
big
small

17. Definition Setting Process Hardening Process
The process of losing plasticity and becoming dense of the paste, which is formed by mixing the cement and water.
Hardening Process
The process of forming hardening cement paste by the paste, which loses plasticity and its strength increases with time.

18. Process of Setting and Hardening
Initial period
Initial dissolving and hydration; mobile and plastic lasting for 5-10min
Incubation period
The performance of gel layer surrounding cement is excellent; particle growth; lasts for 1h
The cement particle expands , bonds and hydrates after the cracking gel layer; Lasts for 6h; Porous spatial net-coagulation structure;Losing plasticity
Setting period
Fillings of gel to capillaries; lasting for 6h~several years.
Hardening period

19. Factors Influencing Setting and Hardening of Portland Cement
Factors such as: fineness and types of cement, blend of gypsum,
age, temperature and humidity which influence setting and hardening of Portland cement.
Fig2.3 Factors influencing Setting and Hardening of Portland Cement

20. 2.3 Technical Properties of Portland Cement
Fineness
Setting Time
Soundness of the Portland Cement
Strength
Other properties

21. Fineness and Properties
Fineness related to the surface area touching with water, so it influences the setting/hardening speed and the properties of cement.
Tab Fineness and Properties of Cement
Fineness
Surface area touching with water
Setting and hardening
speed
Properties
Small
D < 40μ
Great
High
Strength
Too small
Easily
Cost High
Large
D >100μ
Low

22. Fineness Requirements of Portland Cement
Specific Surface Area
According to GB
Specific Surface Area >300 m²/kg
The distribution of particle size is measured by specific surface area instrument
Measure the change of flow velocity when a little air gets across hardening cement paste
Fig Specific Surface Area instrument

23. 2.3 Technical Properties of Portland Cement
Fineness
Setting Time
Soundness of the Portland Cement
Strength
Other properties

24. Setting Time Normal consistency Definition Testing methods
Engineering significance

25. Normal consistency and water requirement of normal consistency :P(%)
It refers to the consistency when the sinking distance of solid cone is 28±2mm.
Water Requirement of Normal Consistency
It refers to the water needed for forming normal consistency cement paste in a certain method.

26. Two test methods for water requirement of normal consistency
Fixed water
quantity method
Changed water
quantity method
Employed mostly by the green hands
We usually follow this when conflicting.

27. Fixed water quantity method
Forming cement paste with normal consistency :
500gC+500×p%W
Measure p%

28. Fixed water quantity method
Fig2.5 instruments for normal consistency

29. Fig2.6 setting time testing instrument
Testing Methods
Test setting time of cement paste of normal consistency at stated temperature and humidity by cement paste setting time testing instrument.
Fig2.6 setting time testing instrument

30. Setting Time Initial setting time
The time from watering cement to cement paste beginning to lose plasticity
Standard require≮45min
--1-3h for the domestic cement in use
Test
distance between testing needle and round container is 4±1mm
Engineering significance
For the purpose of mixing, transportation, placing, vibrating and masonry, the initial setting time should not be early.

31. Setting Time Final setting time
The time from watering cement to cement paste completely losing plasticity and beginning to have strength
Standard require≯390min
5-8h for the domestic cement in use
Test
The sinking distance of the testing needle is 0.5 mm
Engineering significance
The final setting time should not be late so that the cement can be hardened quickly, have the fixed strength and continue to work.

32. 2.3 Technical Properties of Portland Cement
Fineness
Setting Time
Soundness of the Portland Cement
Strength
Other properties

33. Soundness of the Portland Cement
Definition
Reasons for poor dimensional stability
Evaluating dimensional stability

34. Soundness of the Portland Cement
Definition
The process of reducing and averaging volume of the cement in the process of cement hardening.
Poor dimensional stability
Uneven volume change happened in the process of cement hardening, such as cracking, blending
The opposite of soundness of the Portland cement causing the decrease of quality

35. Reasons for Poor Dimensional Stability
Three reasons
too much disassociated f- CaO
too much disassociated f-MgO
too much gypsum

36. Reasons for Poor Dimensional Stability
The hydrating speed of the overburnt f-CaO or f-MgO is slow, f-CaO or f-MgO begins to hydrate after cement hardening and causes the hardened cement to expand and crack.
When added too much, gypsum continues to react with calcium aluminate hydrate to form calcium sulfoaluminate hydrate, whose volume increase 1.5 times as big as gypsum and causes the hardened cement paste to crack. At this time, sulfoaluminate hydrate is called cement bacillus.

37. Evaluating Dimensional Stability
Boiling Method -accelerating test
There are two methods to evaluating dimensional stability:
Disc method
Evaluating dimensional stability of boiled cement disc by observation
Le chatelier soundness method
Measuring expansion of hardened cement after boiling

38. Evaluating Dimensional Stability
Fig.2.7 Poor dimensional stability
Fig.2.8 Boiling testing instrument
Fig.2.9 Le chatelier soundness testing instrument

39. Restrict
The accelerating test method can only test the over-use of f-CaO
f-MgO and gypsum can not be tested by the above test
So they must be controlled in the producing process to avoid over-use
Standard defines
MgO≯5%，gypsumSO3≯3.5%

40. 2.3 Technical Properties of Portland Cement
Fineness
Setting Time
Soundness of the Portland Cement
Strength
Other properties

41. Strength test Compressive strength and bending strength
can be tested by producing standard specimen
（ 40×40×160） which is made by C:S:W=1:3:0.5
and cured in the standard condition
C:S:W=1:3:0.5
test
Standard specimen
40 × 40×160
Compressive
strength
Cured under
the standard
condition
Bending strength

42. Fig.2.10 Strength testing instrument

43. Fig2.10 Strength testing instrument
Compressive strength
instrument
bending strength instrument
Fig2.10 Strength testing instrument

44. Strength Grades According to 3 days and 28 days compressive strength
3 days and 28 days bending strength
Portland cement can be classified into 42.5，42.5R, 52.5，52.5R, 62.5, 62.5R grades.
The strength of every age should not be lower than the required number in GB table.
The cement of every grade can be classified into 2 types, high early-strength(R) ones and normal ones.

45. Technical Properties Analysis
The technical indexes of the cement before using are the 4 items: fineness, setting time，strength and soundness. Fineness, setting time，strength and soundness must be qualified. The cement can be used according to the requirement of the lower grade, if only the strength is unqualified.
If only the strength
is unqualified
Cement of the
lower grade

46. Other Properties Density Bulk Density
g/cm3, commonly 3.1g/cm3
Bulk Density
kg/m3
Density of long-kept cement decreases a little. Free CaO combines with H2O, CO2 in the air to form Ca(OH)2 and CaCO3 with low density.

47. Alkali Content
Alkali content which is donated by calculated value of Na2O+0.658K2O avoids alkali-aggregate reaction.
Alkali content of low alkali cement≯0.6%，or treat between supply and requisitioning parties.

48. Hydration Heat
Most hydration heat is given out at the initial period of hydration and its quantity depends on chemical compound and fineness of cement, mineral admixture and intrusion aid (admixture).
The higher C3S, C3A, the finer the particle, the bigger hydration heat, the more advantageous to the construction in winter, but more harmful for mass concrete

49. §2 Portland Cement Production and Composition of Portland Cement
Hydration, Setting and Hardening of Portland Cement
Technical Properties of Portland Cement
Corrosion and Prevention of Hardened Cement
Characteristics and Application of Portland Cement

50. Corrosion and Prevention of Hardened Cement
Introduction
Representative Corrosion Types
Denudation Corrosion
Sulfate Corrosion
Magnesia Corrosion
Carbonate Corrosion
Acid Corrosion
Origin of Corrosion
Prevention of Corrosion

51. Introduction
The hardened cement paste can still be hardened and the strength can also increase in the normal condition (humid environment or in water).
Corrosion of Hardened Cement
The structure will be destroyed. Strength and durability will be decreased, or totally damaged in corrosive substance.

52. Representative Corrosion Types
Denudation Corrosion(剥蚀)
Sulfate Corrosion
Magnesia Corrosion
Carbonate Corrosion
Acid Corrosion
Alkali Corrosion

53. Denudation corrosion Denudation corrosion
It refers to the corrosion caused by dissolution of calcium hydroxide in soft water.

54. Denudation corrosion Preventive measure
In hard water, the following reaction happens
On the surface, dense calcium carbonate layer will be formed to protect concrete
Beforehand concrete should be carbonized in carbonizing apparatus-Artificial carbonation.
Ca(OH)2 + Ca(HCO3) CaCO3 + H2O

55. Sulfate Corrosion Characteristics
Sulfate medium-sea water, underground water and so on
Sulfate reacts with ingredients in hardened cement to form dilatancy crystal and destroy the hardened cement
Crystallization and expansion

56. Magnesia Corrosion MgCl2+Ca(OH)2 = Mg(OH)2+CaCl2
Characteristics
Magnesia medium-sea water, underground water and so on
Magnesia reacts with ingredients in hardened cement to form freely soluble and dilatancy crystal , and destroy the hardened cement.
MgCl2+Ca(OH)2 = Mg(OH)2+CaCl2
MgSO4+ Ca(OH)2+H2O = Mg(OH)2+CaSO4·2H2O
Crystallization and expansion
Freely soluble

57. Carbonate Corrosion Ca(OH)2+CO2+H2O CaCO3+2H2O CaCO3+H2O+CO2 Ca(HCO3)2
Characteristics
Carbonate medium-sea water, underground water and so on.
Carbonate reacts with ingredients in hardened cement to form freely soluble and destroy the hardened cement.
Ca(OH)2+CO2+H2O CaCO3+2H2O CaCO3+H2O+CO2 Ca(HCO3)2
Freely soluble

58. Acid Corrosion O H CaSO OH Ca SO CaCl HCl ) ( ® + Characteristics
Acid medium-industry environment and so on
Acid reacts with ingredients in hardened cement to form freely soluble crystallization, expansion and destroy the hardened cement.
Freely soluble
Crystallization and expansion O H
CaSO OH Ca SO
CaCl
HCl 2 4 ) ( +

59. Alkali Corrosion Dry air Freely soluble Characteristics
Alkali reacts with ingredients in hardened cement to form freely soluble crystallization, expansion and destroy the hardened cement
Freely soluble
Dry air
Crystallization and expansion

60. Origin of Corrosion
Hydrates such as CH, C-A-H are liable to react with some corrosion substance.
The inner structure of hardened cement is not perfectly compact.
Influence from environment.

61. Prevention of Corrosion
Selection of cement varied with environment features.
Improving denseness of cement.
Prevented coating should be covered on the surface of concrete. Impregnated concrete（浸渍混凝土） should be employed for the special concrete project.

62. §2 Portland Cement Production and Composition of Portland Cement
Hydration, Setting and Hardening of Portland Cement
Technical Properties of Portland Cement
Corrosion and Prevention of Hardened Cement
Characteristics and Application of Portland Cement

63. Characteristics and Application of Portland Cement
High Strength high strength concrete and prestressed reinforced concrete（预应力钢筋混凝土）
Fast hardening fast setting and high early-strength, construction in winter, prefabrication, site cast and so on.
Excellent freezing resistance the winter construction and project suffering from circles of freezing and thawing in cold area

64. Characteristics and Application
of Portland Cement
Poor corrosion resistance the project with erosion substance, such as fresh water and sea water.
Poor heat resistance the project with the requirement for heat resistance
Large heat of hydration disadvantage to mass concrete, but advantageous to thermal storage construction in low temperature season

65. Characteristics and Application
of Portland Cement
Excellent abrasion resistance
road and field.
Carbonation resistance strong protecting effect and applicable to the environment with high consecration of CO2

66. §3 Portland Cement With Mineral Materials
Chapter 6 Cement
§3 Portland Cement With Mineral Materials
Mineral Admixture
Ordinary Portland Cement (P.O)
Portland granulated Blast-furnance-slag Cement (P.S)
Portland-Pozzlana Cement (P.P)
Portland fly-ash cement (P.F)
Composite Portland Cement (P.C)

67. Mineral Admixture Definition Classification Active admixture
Introduction
Secondary Hydration Reaction
Function of Active Admixture
Inactive admixture

68. Mineral Admixture Definition Improving Property
processed or raw mineral
materials when grinding
Adjusting Strength Grade
Lowering Costs
Mineral Admixture is the processed or raw with the purpose of improving cement property, adjusting cement grade and lowering costs.

69. Classification by performance
active admixture (Pozzolan Admixture)
and inactive admixture（filling admixture）
Classification by performance
Inactive admixture
（filling admixture）
Active admixture
(Pozzolan
Admixture)

70. Active Admixture Introduction
It is not hardened after grinding and watering.
But after mixed with lime and water
A secondary hydration activity happens
To form hydraulic cementing material activity
Volcanic ash activity

71. Hydraulic cementing forms
Secondary Hydration Reaction
SiO2 +mH2O + xCa(OH) xCaO·SiO2·nH2O
Hydraulic cementing forms
Consumption Ca(OH)2
Active admixture
Al2O3 +aH2O + yCa(OH) yCaO·Al2O3·bH2O

72. Active Admixture
Although active admixture is not a compound of Portland cement.
The replacement of a portion of cement with active admixture changes the properties of the various types of cement.

73. Secondary cementing reaction
Hydration Reaction
First reaction
Portland cement hydrates
Takes place when portland-pozzolan cement is used or when a pozzolan is added to concrete with portland cement
Secondary cementing reaction

74. Characteristics of Secondary Hydration Reaction
Sensitivity to temperature
Low reaction speed at common temperature
High reaction speed at high temperature
Consumption Ca(OH)2
Improving the structure of pores

75. Consumption Ca(OH)2
When the calcium silicates hydrate, hydrated lime is one of the products of hydration
This leaves a reactive soluble salt in the concrete mass and is responsible for the white encrustations and efflorescence which appears in hydraulic structures where the lime has leached to the surface and reacted with CO2.

76. Function of Active Admixture
Improving products.
Lower costs.
Better the property of cement.
Adjusting strength grade of cement.
Expanding application range.
Benefiting to prevention of environment.
Making full use of industry rubbish.
Protecting the environment.

77. Better the property of cement
Reducing temperature rise
Pozzolanic action occurs very slowly.
Consequently the temperature rise is much smaller

78. Better the property of cement
Reducing alkali-aggregate expansion
A pozzolan is an active, amorphous silica.
Reacting readily with any alkali in the presence of moisture.
The pozzolan, as a very finely divided silica.
Readily consuming the Na2O and K2O from the cement.
Completely dispersing the expansive silica.
Consequently, the alkalis are not available to react with reactive aggregates.

79. To Reduce Harmful Effects of C3A
The harmful effects of tricalcium aluminates can be reduced by use of a pozzolan.
If the pozzolan is used to replace 30 percent of the Portland cement, the percentage of tricalcium aluminates in the total cementing material will also be reduced by 30 percent.

80. Types of Active Admixture
Fly ash
Granulated blast furnace slag
Other active admixture

81. Types of Active Admixture
Fly ash is the flu dust that is precipitated in the smokestacks of coal-burning power plants
Granulated blast furnace slag
composed of the fine particles of shale in the coal which form tiny spheroids of glass when exposed to the hot flame of the furnace

82. Types of Active Admixture
Other active admixture such as
silica fume(硅灰)
Diatomite（硅藻土）
ground pumice （磨细浮石）
other volcanic rocks（火山岩）

83. Inactive Admixture Characteristics
It can’t form hydraulic cementing material with gelatification（胶凝化作用） after grinding and mixing with lime in water.
Quartz
Clay
Slow cooling slag

84. §3 Portland Cement With Mineral Materials
Chapter 6 Cement
§3 Portland Cement With Mineral Materials
Mineral Admixture
Ordinary Portland Cement (P.O)
Portland granulated Blast-furnance-slag Cement (P.S)
Portland-Pozzlana Cement (P.P)
Portland fly-ash cement (P.F)
Composite Portland Cement (P.C)

85. Ordinary Portland Cement
Introduction
Technical Properties
Strength demand
Application

86. What is Ordinary Portland Cement
Mixing materials
P.O
Grinding
Hydraulic
cementing material
Clinker
Ordinary Portland Cement is the hydraulic cementing material.
It is made by grinding a few mixing materials and proper gypsum.
The maximum quantity of mixing materials should be no less than 15%.
Gypsum

87. Technical Properties Sieve residue ≯10%
Measure the screening rate（筛选率） of the square mesh sieve with 0.08mm
Screening Method
Negative pressure Sieving method
Water pressure sieving method
Dry sieving method

88. Technical Properties Strength grades
It can be classified into 6 strength grades :42.5, 42.5R , 52.5R , 52.5, 62.5, 62.5R
Requirements of strength are in the following table.
Final setting time can not exceed 10h

89. Same to Portland cement
Technical Properties
Same to Portland cement
Other requirements of technical properties and range of applications are same with Portland cement.
The mineral compound is in the range of Portland cement for a few quantity of mixing materials.

90. Tab.3.1 Strength Demand of Ordinary Portland Cement
Strength grade
Compression strength (MPa)
Fracture strength（MPa） 3d
28d
32.5
32.5R
42.5
42.5R
52.5
52.5R
11.0
16.0
21.0
22.0
26.0
2.5
3.5
4.0 5
6.5
7.0

91. Application of P. O
It is the main type of common cement and mainly used in the project of concrete and reinforced concrete.
The application range is the same with Portland cement.

92. Thank you very much