Table of Contents
What Is Fat Lime?
Fat lime is also known as Rich lime, High calcium lime, Pure lime, White lime. It is obtained by calculating limestones.
When water is added to this lime, it produces hissing sound, a lot of heat is liberated it cracks and its volume is increased by 2-3 times the presence of air is essential for its setting. Hence it does not set.
- Under water.
- Below Ground.
- In interior joints of a thick wall.
What Is Hydraulic Lime?
This lime does not require Co2 from the atmosphere for the setting. Hence it can set under-water. It is used in construction works. Strength is required.
This lime is not suitable for plaster-work because any unslacked particle may slake after some days causting blistering in plaster.
To improve this property this lime is ground to powder and then mixed with sand the mortar thus prepared is kept in a heap for about a week, and it is ground again. Such mortar prepared from hydraulic lime suitable for plaster-work.
Depending upon the percentage of clay content, hydraulic lime is divided into the following types,
Type of Hydraulic Lime.
- Eminently Hydraulic Lime.
- Moderately Hydraulic Lime.
- Feebly Hydraulic Lime.
1. Eminently Hydraulic Lime:
- Clay content – 21 to 30%
- Slaking – Slow with difficulty
- Setting – About 24 hours
- Hyraulicity – Eminent
- Uses – Can be used in important masonry works in place of cement
2. Moderately Hydraulic Lime:
- Clay content – 11 to 20%
- Slaking – After 1.5 hours
- Setting – About one week
- Hyraulicity – Moderate
- Uses – Masonry works
3. Feebly Hydraulic Lime:
- Clay content – 05 to 10%
- Slaking – After few minutes
- Setting – Sets in water after about 3 weeks
- Hyraulicity – Feeble
- Uses – Ordinary masonry works.
Difference Between Fat Lime and Hydraulic Lime
|Use||Plastering, white washing preparing and mortar with surkhi mix.||
Suitable for thick walls, works below ground in damp condition
|Strength||It is not strong and hence can not be used where strength is requierd.||
It is strong and can be used like cement
|Slaking||Slakes vigorously with hissing sound and cracking volume increased by 2 to 3 times slaking continues upto 3-4 hours.||
Not much heat is liberated. No hissing sound or cracking volume increases by 1.2 times slaking continues up to 1-2 days
|Setting||Sets slowly in presents of air. Absorbs CO2 from atmosphere and from CACO3. It does not have hydraulicity and hence can not set under water.||
Sets under water – CaO content sets like fat lime calcium silicate & crystalline structures are formed they set like cement. It possesses hydraulidty.
|Composition||More Percentage of CaO clay content less then 5%||
Ca + clay content from 5 to 30 % and some % of iron oxide