Torrent0 pages

www.proceq.com
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permeability tester
Fast, reliable and non-destructive measurement of the permeability of concrete structures
The permeability of concrete at the surface (concrete cover) has been recognized as a major factor in determining the durability of concrete structures. Many specialists emphasize the importance of this property and the possibility of
measuring it reliably - not only in the laboratory but also at the building site.
P
ermeability measurements
The particular features of the TORRENT method are a two-chamber vacuum cell and a pressure regulator, which ensure that an air flow at right angles to the surface is directed towards the inner chamber. This permits the calculation of the permeability coefficient kT on the basis of a simple theoretical model.
The unit has a user-friendly menu technique and measures the pressure increase as a function of time according to a specific sequence. The associated data is automatically collected by the display unit and the permeability coefficient kT and the depth of penetration L of the vacuum are calculated. The measurement takes 2-12 minutes, depending on the permeability of the concrete. In the case of dry concrete, the quality class of the concrete cover can be read from a table using the kT value. In the case of moist concrete, kT is combined with the electrical concrete resistance ñ (rho) and the quality class is determined from a nomogram.
The TORRENT permeability tester is based on investigations which were carried out by the research centre of „Holderbank
Management and Consulting Ltd.“, Switzerland. The result of these measurements, which were made in the laboratory
and on the building site, are in good agreement with laboratory methods, such as oxygen permeability, capillary suction, chloride penetration, etc.
Standard: SN 505 262/1, Annexe E
Air flow to the two chambers
of the vacuum cell
Inner chamber, pressure pi
Outer chamber, pressure Po
Po = pi
Air flow to the outer chamber
Air flow to the inner chamber
L = Depth of penetration of the vacuum
In the case of moist concrete, the measured permeability is lower, i.e. the concrete quality seems to be
too good. This effect can be corrected using the electrical resistance ñ of the concrete. The concrete quality class is determined
from kT and ñ in a nomogram.
Nomogram for concrete quality class
Atmospheric
pressure pa