The art of construction of stone unit bonded together with mortar is called stone masonry. The strength of stone masonry depends upon the types of stones of the mortar used.
General Principle to be Considered in Stone Masonry:
The following point should be considered while supervising the stone masonry.
– The stone used should be strong, tough, hard and free from cracks and cavities.
– Each stone should be well-wetted before use so that it does not absorb water of mortar.
– The stone should be dressed properly according to types of masonry.
– Masonry works should be raised uniformly.
– Broken stones should not be used for facing and backing.
– Wall should be laid completely vertical.
– If stone masonry is to carried out at a higher level, double scaffolding should be used.
– No tensile stress should be produced anywhere because a stone is weak in tensile strength etc.
Types of Stone Masonry
1) Rubble masonry:
In this masonry, the stone of irregular shape and size are used which are taken from quarrying. The strength of rubber masonry mainly depends upon the quality of the mortar used.
a) Coursed rubble masonry:
1) Used in public and residential buildings.
2) Its types are explained as sort-1, sort-2, sort-3.
b) Random rubble masonry:
1) Irregular shape and size are dull.
2) The arrangement is good.
3) Used in residential building and compound wall.
c) Uncoursed rubble masonry:
1) Stone is not dressed but knocking off the corner is done.
2) The large stones are laid first and the gap is maintained by using small stones.
3) Wall is maintained every 300 to 500 mm.
d) Dry rubble masonry:
It is similar to course double masonry but there is no use of mortar in joints. It is used in the compound wall and retaining wall.
e) Polygonal rubble masonry:
1. Face stone is cut in polygonal rubble shape.
2. Skilled manpower is required.
f) Flint rubble masonry:
Stone uses are flint (bed stone of silica which is irregular in shape). Use in those places where flint rocks are available.
2) Ashlar Masonry:
In this masonry, square or rectangular block of stones are used and the height of stone varies from 250 to 300mm. The length of stone used in this masonry should not be greater than three time the height.
a) Ashlar fine masonry:
A fully dress stone is only used. They are fine from all sides. Mortar thickness is minimum(i.e 3mm). It is a costly type of masonry.
b) Ashlar rough tooled masonry:
Bed and slide are finely chiselled.
1.. Mortar thickness is 6mm
2. A strip of 25mm around perimeter of stone is provided.
c) Ashlar rock or quarry faced masonry:
1. A strip of 25mm around perimeter of stone is provided.
2. Other faces are used as the same received from a quarry.
3. It is comparatively economical than the previous one.
d) Ashlar chamfered masonry:
1. 25 mm strip is provided.
2. The edge of the stone is chamfered at 45 degrees.
3. Appearance is neat faced.
e) Ashlar block in course masonry:
– In front face, the dressed stone is used and in back, rubble masonry is used.
– Mortar thickness is 6mm.
– This type of masonry is used in the construction of retaining public buildings and temples.
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