Stone splitting tools
Natural stone is extracted in quarries using special processes known as stone splitting tools .
One of these stone extraction methods is the splitting of the stones with wedges, either by hand or with the help of machines.
Columns with hand tools
The simplest method of splitting stones in quarries is via leverage, using existing crevices with lifting bars and breaking the stone out of the stone wall. A special stone splitting process is used in the Solnhofen slab limestone quarries , using a kind of hoe to break out the polygonal slabs.
A method that has been used since ancient times and is still found today - but is becoming increasingly rare - is splitting with hand tools by knocking in triangular slots in the desired direction for splitting the stones. Iron wedges are inserted into these slots and iron sheets that match the wedge sizes are inserted into the flanks of the slots to optimize the wedge effect . The iron sheets are called springs. Stonemasons call this stone cleavage "crushed", which was mainly used to split hard stone .
From antiquity to the early 20th century, wooden wedges were also used to split stone. For this purpose, holes are made in the stone and wedged with dry wood. Moistening the wood creates a high swelling pressure , which splits the stone. With the advent of the so-called "patent wedges" (see below), the wooden wedge method was no longer economical and was forgotten.
Every natural stone has a so-called warehouse. This means that the minerals are stored horizontally to the earth's surface and thus align themselves in the stone. Stonemasons use this storage when splitting the stones. A natural stone can be split with the bearing with less effort and the stone surfaces are more even than when splitting against the bearing. One of the reasons stonemasons call this division against the camp is pushing.
The harder the rock, the further apart the drill holes can be set, for example, for hard rock granite, drill hole spacings of up to 40 cm can be selected depending on the type of granite. With soft rocks , such as open-pored limestones, the distance between the drill holes can drop to 10 cm, depending on the type of sandstone .
A more modern method is to drill holes with hammer drills powered by compressed air. So-called "patent wedges" are inserted into the drill holes. They consist of wedges and specially shaped springs made of metal (see above) that optimize the wedge effect.
In both of the above methods, the wedges used are driven in with sledge hammers to split the stone.
Recently, holes with pneumatic hammers have been drilled into the rock layer, which is also called bank, in the quarry and then oil-hydraulic splitting devices are used, which split the rock layer with high pressure. Then so-called release cushions made of sheet metal are inserted into the release joint, which, filled with air or water pressure, push off the stone layer in order to then extract them as raw blocks with heavy equipment ( wheel loaders , excavators ).
art
After an apprenticeship as a stonemason and working at the Dombauhütte in Cologne, the artist Ulrich Rückriem began to design stone sculptures by separating stones with splitting wedges and putting them back together again. After studying at the Cologne Werkschulen , he has created numerous art objects in public spaces from raw stone blocks since 1968. In doing so, he has developed an artistic process that is unique to him, in which he joins the split cubic or rectangular shapes of an originally closed stone block after splitting it together.
Today's stone extraction techniques
Nowadays it is becoming increasingly rare that explosives are introduced into boreholes , which split off the stone accordingly (better blast off ). The disadvantage of this method is massive damage to the stone blocks, as well as high costs and risks. Another method is to split off stones with so-called expansive substances. These are cements that are filled into the drill holes and produce a driving effect when they set. Use is restricted to the summer months.
Today, natural stone is extracted mainly with " cutting " and wire saws in the quarry. If the stone blocks are too big, the splitting techniques mentioned above are sometimes used to bring them to the desired format.
Comparable technologies
Similar tools
jobs
other topics
literature
- Fritz Mangartz, Olaf Pung: The splitting of wood wedges in old stone quarrying. In: The cut. Magazine for art and culture in mining . 54th vol., No. 6, 2002, ISSN 0003-5238 , pp. 238-252.
- Mary E. Gage, James E. Gage: The art of splitting stone: early rock quarrying methods in pre-industrial New England, 1630-1825 , 2nd edition. Amesbury, Mass., 2005, ISBN 0-9717910-2-3 ( limited preview in Google Book Search)
Individual evidence
- ↑ Robert Konopasek: spy oven, a quarry from Roman time in Carinthia. S. 51. In: res montanarum 38/2006
- ↑ Angelina Dworakowska: Wooden wedge in ancient quarrying practice: critical examination of the state of research. In: Archeologia (Warszawa) 38, 1987, pp. 25-35. For example, wooden wedges were found in the ancient quarry of Luni ( Carrara , Italy) which were still in their wedge pockets, cf. Enrico Dolci: Marmora Lunensia: Quarrying Technology and Archeological Use. In: Norman Herz, Marc Waelkens (Eds.): Classical Marble: Geochemistry, Technology, Trade. Dordrecht / London / Boston 1988, p. 81 ( Nato ASI Series Vol. 153.)
Web links
Images and videos of splitting techniques, including wood wedge splitting