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Germann Instruments, Inc.
Test Smart – Build Right
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Figure 6
The drill machine and
the CORECASE CEL-100 with
coring rig and the diamond saw
for producing the specimens.
Figure 5
The precision steel
mould for 100 mm in diameter,
200 mm high specimens.
3.
Preparing and producing the specimens
In laboratory, specimens may be cast in a 100 mm diameter steel moulds,
200 mm high (
see figure 5
),
with the MRLN-1009 precision steel mould, reusable, 100 mm diameter, 200 mm high (internal
dimensions), with an accuracy of 0.02 mm on the dimensions.
Prior to stripping of the cast specimen the top and bottom lids are
removed and the container opened slightly axially by applying a pressure
with the screws in the welded-on studs. The mould allows specimens to
be produced with totally plane end-faces perpendicular to the circular
specimen. The specimens may be also used for the MERLIN Bulk
Conductivity Systems as well as for ASTM C 1760 Bulk Electrical
Conductivity of Hardened Concrete.
Alternatively, the specimens may be produced in the lab by coring. For
cored specimens, the CEL-100 CORECASE coring rig is recommended to
be used (
see figure 6
). The rig produces accurately the correct 100 mm
+/-0.5 mm core diameter.
For sampling on the structure, the same CEL-100 CORECASE coring rig is
also recommended. Drill to a minimum depth of 210 mm. Then break the
core using a hammer and chisel and extract it. If a different coring rig is to
be used, make sure the diamond drill bit has an inner diameter of 100
mm.
The specimens for ASTM C 1202 or NT BUILD 492 are saw cut to a length
of 50 mm +/-1 mm, e.g. by using the PR-1060 saw that aligns the core
end faces and ensure a slice cut perpendicular to the axis with a
thickness of 50 mm. Be careful to avoid breaking of the edge when the
saw-cutting is close to termination.
If the sample is cut too long or unevenly, the cell will not tighten properly
or the mesh of the
Proove’it
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cells may get damaged.
The cells are designed to test the specimens without resorting to epoxy
coating provided the specimen diameter is regular and the correct
gaskets’ size has to be selected
(See Table 2)
. However, the technician
may choose to use epoxy on the circumferential surface to eliminate
any possible stray current.
For such applications, the epoxy is mixed in a pot (about 10 grams are needed for each specimen). With a
brush, apply a thin layer to the circumference face of the specimen. Make sure no epoxy is applied to the
end faces. Allow the epoxy to dry on a table with a piece of paper in between. Turn the specimen upside
down after 5 minutes to ensure that the epoxy is equally distributed along the surface.