Field practice of classification of 'Bricks'
First class bricks
Colour - Thoroughly burnt with deep red or copper colour
Edges - Sharp edges, smooth surface, rectangular with parallel and strait edges & square corners
Texture - Uniform
Abrasion resistance - No scratch should be made by finger nail
Water absorption - about and not more than 12-15 % of dry weight when immersed in cold water for 24 hours
Sound - Mettalic or ringing sound when two bricks struck aginst each other
Crushing strength - Not less than 10.5 N/mm²
Uses - Exposed face work, ponting, flooring and reinforced brick work
Second class bricks
Usually second class bricks have more or less same properties as first class except that
Water absorption - A little higher about 16-20 % of its dry weight when immersed in cold water for 24 hours is allowed
Crushing strength - Not less than 7 N/mm²
Small cracks and irregularities are permitted
Uses - All normal masonry works, hidden masonry works and reinforced bricks
Third class bricks
These bricks are of poor quality than second class bricks
Colour - Light in colour
Texture - Underburnt
Abrasion resistance - soft, leaves impression when scratch by finger nail
Corners are round, and irregular edges
Water absorption - About 25 % of dry weight
Uses - for temporary structures only
Fourth class bricks
Texture - Overburnt
Shape - Badly distorted in shape and size
These bricks are brittle in nature
Uses - As brick ballast for foundations and floors & road metal.
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