1. Chapter 3
Cement

2. §3.3 Portland Cement With Mineral Materials
Chapter 3 Cement
§3.3 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)

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

4. 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.

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

6. 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

7. 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

8. 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.

9. 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

10. 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

11. 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.

12. 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.

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

14. 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.

15. 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.

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

17. 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

18. Types of Active Admixture
Other active admixture such as
silica fume
diatomite
ground pumice
other volcanic rocks

19. Inactive Admixture Characteristics
It can’t form hydraulic cementing material with gelatification after grinding and mixing with lime in water.
Quartz
Clay
Slow cooling slag