Dividing and cutting blocks

Stone is seldom used as an unfinished rough block. It is usually divided into smaller units. This can be done in several ways.

Wedging is shown in Figure 7.2. The alignment of the wedges happens in three stages. It requires skill, good knowledge of the nature of the stone and the direction of its layering, and much work.

Guillotining is possible for smaller blocks with clear layering. This splits the stone with one blow and is the most labour and energy-saving

technique. It is also the principle upon which modern equipment research and development bases its work. Some methods create an artificial tension within the rock with the help of a strong vice. Fractures then occur, which spread out when the axe falls, and in a single moment maximize the tension in one direction. The maximum size available for a rough block, using modern equipment, is up to 250 x 50 cm, depending upon the type of stone. Smaller splitting machines can be carried by two people; and can split stone up to 10 cm thick and also work on loose stone.

Sawing is a common method for dividing blocks. A circular saw or frame saw, preferably with a diamond blade, is used. The frame saw is often used for the production of external facade panels (Figure 7.3). The capacity of a frame saw on hard stone is approximately 30 cm per hour. Circular saws are used for all types of stone and cut considerably faster.

Jet flame can be used on quartz stone.

Waterjet techniques have been developed for cutting stone, using a thin spray of water at an extremely high flow speed which cuts stone like butter.

The finishing process. Further processing is determined by how the stone is to be used. For structural use and foundations stone does not need much working - the surface can be evened out with a hammer. For cladding panels, tiles, etc. the stone requires planing, grinding and polishing.

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