1. Chapter 2
Air Hardening Inorganic
Binding Materials

2. §2.3 Lime Chapter 2 Preparation of lime (quick lime)
Slaking and hardening of lime
Technical properties of gypsum
Applications

3. Preparation of lime quick lime
Preparation of lime : lime stone was heated
and decompounded into quick lime.
CaCO CaO
1000～1100℃ CO2＋
MgCO MgO
quick lime

4. Preparation of lime
According to MgO content, there are two types of quick lime:
Calcium quick lime and high-magnesium quick lime.
MgO≤5％ Calcium quick lime
MgO≥5％ High-magnesium quick lime

5. Preparation of lime
According to temperature and time of the preparation , there are 2 types of quick lime: over-burnt lime and under-burnt lime.
tem\time↑→ over-burnt lime：clay melts, fills or enwraps the surface of lime →high solidity→lime slakes slowly
tem\time↓→ under-burnt lime：CaCO3 does not decompose enough and the productivity is low

6. Slaking and hardening of lime
Slaking of quick lime： 1
Quick lime reaction with water gives slaked lime
Slaked lime
Slaking method: It will take more than two weeks to use the quick lime in the water.

7. Slaking and hardening of lime
Slaking of quick lime： 1
The characteristics of the reaction is that:
①the large exothermic amount and the quick exothermic speed
②volume increase ：1～2.5 times

8. Slaking and hardening of lime2
The process of hardening includes : crystallization and carbonization.
Ca(OH)2 crystal is formed in crystallization, whose characteristics is quick reaction inside.
CaCO3 is formed in carbonization, when Ca(OH)2 absorbs CO2 in the air, whose characteristics is slow reaction and crystal from outside to inside.

9. Hardening of lime 2 The process of hardening Crystallization
Carbonization
Ca(OH)2
crystal birth
Main changes
Characteristics
Reacting
quickly inside
Crystal from
outside to inside
making CaCO3

10. Technical properties of gypsum1
Technical standard：
Building quick lime （JC/T479-92）
(1)Technical standard
The content of CaO+MgO、the content of CO2、
the content of unhydrated grain and the content
of paste.
(2) Classification
Calcium quick lime and high-magnesium quick lime.
(3) Grades
Top-rate materials, first-rate materials, qualified-rate materials.

11. Technical properties of gypsum
b. Building ground lime（JC/T480-92）:
Technical standard
The content of CaO+MgO and CO2
(2) Classifications
Calcium ground lime and high-magnesium ground lime
(3) Grades
Top-rate materials, first-rate materials,
qualified-rate materials

12. Technical properties of gypsum
c. Building ground slaked lime （JC/T481-92）:
(1)Technical standard
The content of CaO+MgO、free water、soundness and fineness
(2) Classifications
Calcium ground slaked lime, high-magnesium ground
slaked lime and dolomite ground slaked lime.
(3) Grades
Top-rate, First-rate, Qualified-rate

13. Technical properties of gypsum2
Properties:
Quick setting and hardening, low strength
Good plasticity of paste（rich water retentivity）
c. Large shrinkage of volume
d. Poor water resistance

14. Applications Ground quick lime, Ground slaked lime, Lime paste
Improve the utilization ratio of lime
Silicate products：
Example： lime-sand brick,
Carbonated lime board
Making cement without clinker
Ground quick lime + active blended materials + gypsum
Ground quick lime +sand +water

15. Chapter 2
THE END