Stones should be hard and of approved quality and colour and free from defects. Tests for quality may be studies from IS: 1122 to 1127. Crushing strength should satisfy requirement of IS: 1905. Stones should be carefully laid and solidly bedded in mortar, tailing back and well bonded into the backing.
Face stones from opposite faces should bond together and for thicker walls backing should bond well with the facing. Masons should never be allowed to make two faces of wall say 15 cm to 20 cm thick and fill the intervening space with spalls and smaller stones.
Size of stone, natural bed on which to be laid, dressing of face, bed and joints should conform to contract specification and approved samples. In the hearting, plum stones should be left to slightly project above the height of course. Quoins should be laid alternately in stretcher and header.
Cross walls, buttresses and returns should be built simultaneously with interconnected bonds.
Other salient points are as under:
- See that stone used is the best available as per approved sample and that the walls do not consist of facings of gomi stone with the intervening portion filled with small pieces and rubbish. The ideal to be aimed at is a maximum of large stones and a minimum of mortar.
- Avoid laminated stone.
- See that all bond stones are marked with white washed crossed by contractor. Occasionally uncover stones so marked to check ht they are, in fact, bond stones.
- See that bringing upto courses has bee done as specified and that face and be is are squared back as required.
- See that the requirement of height/depth ratio 06 the stone is maintained as specified.
- See that no stone shall pass through a circular ring of 15 cm inner diameter and that the thickness of the stone in any direction is not less than 10 cm.
- See that no stone tapers to a point.
- Check all verticals and jambs of openings for positions and sizes. Check walls for plumb.
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