The subject grouting grouting and its influence has been discussed in several forum. In some circles, grouting has been perceived as disturbing and costly factors in the production of underground facilities, although, in fact, we are increasingly building in urban and sensitive areas, where the needs of soil and mountain sealing have become more and more critical.

Leakage in subterranean plants has proved to be very costly, not least considering that this led to groundwater cuts, which in turn caused major economic consequences to prevent consequential damage to the environment, surrounding buildings, etc.

Grouting has been and remains an important part of underground operations in Sweden. Large resources have been put down, not least in research and development. For decades, research and development has been pursued within the design principles; Geology, hydrogeology, materials and production. Many important literature has been published as increased knowledge and understanding of the topic of design. At the same time, many underground facilities have been produced with dedicated production staff. Through many years of practical experience, they have learned the profession ”learning by doing”, which led to the phrase ”we have always done this”. How did we get the enormous knowledge and experience the production staff possesses?

Questions that can be asked are how we can successfully convey the conclusions of all research to our production staff so that they can combine these with their own experiences and implement established procedures, but, in particular, have the opportunity to highlight the experiences and difficulties they encounter In the daily production.  



Sprayed concrete or shotcrete is a concrete intended to be applied to a single mold through a high pressure air spraying process. The difference between sprayed concrete and ordinary concrete for buildings lies in the casting methods and the fully mechanized handling. Shotcrete consists of a composite rigid composition of cement, silica, natural gravel 0-8 mm, additives and water. Shotcrete can also be reinforced with steel fiber and plastic fiber. Steel fiber is used where static reinforcement is needed and plastic fiber for better crack control. There are two separate production methods: dry spraying and wet spraying method. Most commonly occurring is the wet spraying method. The machine equipment differs between the two methods.


• As an operational boost in tunneling and mining

• As permanent reinforcement in tunnels and mountain areas

• Concrete concrete in subway stations and underground railway stations

• For repair of damaged concrete structures, such as sidebars and pillars on bridges, quays and fire damages

• In thin shell constructions, slabs or barriers

• Slowed reinforcement around road lanes

• Within defense facilities

Shotcrete is particularly interesting for use in rock areas and tunnels. The blasted rock contours are often uneven and coarse, sometimes combined with church formations, which makes traditional formatting and casting techniques impossible to apply. Due to the fact that the concrete can be sprayed directly onto the rock surface, it fills out all major cracks and cavities. It binds more or less loose stone blocks and prevents future fall outs and races. As an operational boost during the production phase, shotcrete is used to prevent the deposition of loose stones and blocks. This happens when the shotcrete fills out all the cavities and binds cracks between the blocks. But also by redistributing rock loads to a more stable mountain through adhesion or shear. When adhesion is lacking, the shotcrete can act as an elastic membrane and absorb some bending stresses.

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