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Hannu Luodes, Geological Survey of Finland (Finland)
Nike Luodes, Kainuun Etu Oy (Finland)
Soile Aatos, Geological Survey of Finland (Finland)
Päivi Heikkinen, Geological Survey of Finland (Finland)
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During 2005-2007 Geological Survey of Finland conducted a large research project on the properties of Finnish natural stone materials focusing especially on the waste rocks extracted in quarry production. The project researched the petrographic, chemical, mechanical and physical properties of these materials. The materials were also characterized environmentally. Legal aspects concerning the waste rocks originating from the Finnish natural stone production were summarized. Some chemical qualifications set for rock-based raw materials by a few conventional rock-consuming businesses were described.
A total of thirty-three natural stone quarry areas throughout Finland were selected for the study. The quarry areas were evaluated focusing on the amount, physical appearance and properties of the waste rock. Material samples of the block production waste as well as samples of weathered rock were taken to analyze the full range of the properties of the waste rock. A comparison of the mechanical and physical properties between the primary product and the waste rock was made to evaluate the possibilities for waste rock use as a geological raw material.
The waste rock of natural stone quarrying is usually petrographically similar to the primary production rock. It can have some defects in colour or texture that prevent its use, though. The rock extracted from the weathered surface layers or near fracture zones can also have too low quality for primary production. According to petrographic, chemical, mechanical and physical properties, the variation of the results between the primary production rock and the waste material from the block production is within the natural variation of rock body in general.
A study of the environmental acceptability for the most common waste rock types was also done. A preliminary procedure for environmental characterization of the secondary materials of natural stone production was outlined. The secondary rock materials of Finnish natural stone quarries can be considered environmentally sound, since almost all the studied secondary rock materials revealed environmentally inert characteristics. Few exceptions were observed, for example waste rock materials excavated in natural stone rock bodies near metalliferous or sulphidised bedrock areas. However, even those secondary rock materials may still have economical value if their technical and economical usability is met in some other rock-consuming businesses.
Waste rock of the Finnish natural stone production has already been used or could be used, for example, as earth, water and environmental construction material and as a raw material for rock aggregates, concrete and ceramics. With further material invention method and product development the natural stone waste rock materials could be used more efficiently as a sustainable raw material in rock-consuming industries.
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