LIME - Building Materials short notes and previous year questions

LIME


• BC 4000 Egypt Rome 
• Lime is an oxide of calcium, CaO 

CALCINATION : process of converting limestone into redness nature 

HYDRAULICITY : process of hardening in the presence of moisture 

QUICK LIME / LUMP LIME / CAUSTIC LIME ( CAO ) 
• Formed by the calcination of limestone 

SLAKING 
• Converting quick lime to hydrated / slaked / lime water 
• 2 - 3 hrs for completion 
• In theory water content of 32 % of cao is taken 
• In practical condition 2 - 3 times WC taken 

• MILK OF LIME : pourable suspension of slaked lime (4-6 times water content of cao ) 




CONSTITUENTS OF LIME

1. CLAY 
• 8 - 30 % 
• Improves hydraulicity 

2. SOLUBLE SILICA 
• Silicates of mg, ca, al 
• Improve hydraulicity at high temp 

3. MAGNESIUM CARBONATE 
• Slows down slaking process 
• Increase setting time 
• It can replace clay content in limestone by 30% 

4. ALKALIES / METALLIC OXIDES 
• Accelerated hydraulicity 

5. SULPHATE : speedup slaking , reduce setting time 

6. PYRITES : should not contain pyrites 


CLASSIFICATION OF LIME

1. FAT LIME / QUICK LIME / WHITE LIME / PURE LIME / HIGH CALCIUM LIME 
• only 5 % impurity , 95 % cao 
• Min quantity max area ( white washing , plastering) 
• 2 - 2.5 % volume increase 
• White color 
• Low strength 
• Has no hydraulic property Not used in underwater , masonry works 
• Shurki or pozzolona added to improve strength

2. HYDRAULIC LIME 
• High strength 
• Used in underwater , masonry , rcc works 
• High setting time 

Feebly  
• Clay content 5 - 10 % 
• Slakes in few minutes 
• Setts in 3 weeks 
• Low hydraulic property 

Moderate / medium 
• Clay content 11 - 20 % 
• Slakes in 1 - 2 hrs 
• Setts in 1 week 

Eminent
• Clay content 21 - 30 % 
• Slaking difficult 
• Setts in 1 day

3. POOR LIME 
• Clay content > 30 % 
• Cannot be used for construction 
• Slakes and sets very slowly 





PREVIOUS YEAR REPEATED QUESTIONS BASED ON LIME 


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