MORTAR

• Binding material ( bond strength ) + fine aggregate ( rigidity, prevent shrinkage ) + water ( flexibility & plasticity ) 
• Ph of water - potable water - should not be less than 7 
• Water quality code - IS 456 

FINE AGGREGATE 
• Major component - Silica / oxides of silica 
• Major mineral component - quartz + feldspar 
• Fineness index used for mortar : 2.5 - 3 ( >2.5 , < 3 ) 

• Fineness index : relative size of fine aggregate to coarse aggregate

Aggregate type and Fineness index 
Fine  : 2.2 - 2.6
Medium   :  2.6 - 2.9
fine coarse  :  2.9 - 3.2 

CLASSIFICATION BASED ON ORIGIN 

PIT SAND  
• Collected form pit of depth 1 - 2 m 
• Red orange 
• Angular 
• High bond strength 
• Used in superior works 

RIVER SAND 
• Collected from river 
• White 
• Spherical, rounded 
• Low bond strength 
• Used in plastering works 

SEA SAND
• Collected from sea shore 
• Brownish yellow
• Round 
• Not used in any type of construction due to salt content

BULKING OF SAND 
• Expansion of sand due to contact with moisture 
• 18 - 38 % volume increase due to 5 - 6 % moisture content 
• Maximum bulking occurs at 5 %



LIGHT WEIGHT  MORTAR
• < 15 KN/m3 
• Only very fine particles included 

HEAVY WEIGHT MORTAR
• > 15 KN/m3 • Medium fine particles


SPECIAL TYPE OF MORTAR 

i. fire resistant mortar : aluminum cement + fire brick powder 
ii. Light weight mortar : lime + saw dust / pumice stone 
iii. Packing mortar : resists oil passage iv. Sound absorbing mortar : density : 6 - 12 KN/m3 v. X ray shielding mortar : density - 22 KN / m3

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