Miscellaneous type rubble

. Polygonal rubble masonry

In this type, stones are hammer finished on the face to an irregular polygonal shape.

If stones are roughly shaped to form rough fitting, such a work is called rough picked work. If stones are carefully shaped to form close fitting such a work is called close-picked work.

• Flint rubble masonry

In this type the main material is “flints or cobbles”  and is used that have  vary in width and thickness from 7.5 cm to 15 cm and length vary from 15 cm to 30cm . The stones are extremely bard but brittle.

The strength of such walls can be increased using a lacing course of thin long stones or bricks at 1 to 2m vertical intervals.

Fig3. Polygonal Rubble Flint Rubble masonry