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GENERAL:
Industrial floors usually consist of a
load bearing concrete slab or substrate topped
with wearing course. The wearing course must be
firmly and durably bonded to the substrate to
ensure the function of the floor as whole. At
the same time, all forces acting on the floor
must be diverted through the substrate to the
structure of the building. For this reason
particularly high importance is attached to the
substrate.
SUBSTRATE:
The strength of the substrate must be high
enough to take mechanical loads. The higher the
load the higher the strength requirements. In
the case of concrete, requirements are normally
satisfied with a compressive strength of at
least 25 n/mm2.
In general, FAIRMATE industrial floor system can
be laid directly onto the concrete substrate, as
a wearing course. However, a compact surface
structure is required that does not need to be
particularly smooth.
On occasions subscreeding may be necessary to
enhance the strength of the substrate and / or
to level the wearing course. The minimum
concrete compressive strength necessary should
be > 25 N/mm2. a substrate pull off strength of
>1.5 N/mm2 is required. If high moisture levels
are present, only systems open to diffusion may
be used. However, please consult our technical
service.
Because of their sensitivity to water, magnesite
and anhydrite screeds may not be moistened
(remaining moisture magnesite < 2%, anhydrite <
0.5%). Layers of wax often found on the surface
of such coatings pose a particular problem.
Asphalt screeds are problematic substrates,
because they deform under mechanical load, are
susceptible to solvents and can be coated only
with special systems. Please consult our
technical service.
TESTING THE SUBSTRATE
The condition of the substrate must be tested
before each surface treatment. The following
check-list should be observed :
-› Moisture
content : Instrument test by measuring, e.g.
with the CM-
instrument (epoxy
resin coatings max. 6%, polyurethane coatings
max.
4%)
-› Compressive
strength : Test with Hammer, cube test or core
test
-› Tensile
strength (in special cases)
-› Surface
pull off strength : Test with Elcometer adhesion
tester or similar,
minimum requirement
: 1.5 N/mm2
-› Damage
to reinforcement : Visual inspection, chipping
out, opening of
cracks,
determination of extent of carbonation,
alkalinity test (see also
chloride test)
-› Existing
finishes : Test by visual inspection, scratching
and cutting tests,
adhesion test,
sample area if necessary.
-› Dirt
and oil contamination : Visual inspection and
wetting test
-› Chloride
content : Chemical analysis of drill dust, at
different depths
-› External
factors affecting moisture content : Check for
level of water
table, existence of
membrane in the original plans, seasonal
adjustments, history
of problems. Take drill cores if necessary
-› Floor
level variations visual and / or specialist
tests (Please consult our
technical service
for super flat floors)
-› Cavities
: Sound out of the floor with Trailing hammer
Method
-› Cracks
: Visual inspection, measurement inspection.
Crack movements,
wet or dry.
Texture : Visual inspection, water absorption
The pull of strength of the substrate must,
after preparation, achieve a minimum of 1.5
N/mm2.
For proper adhesion of any surface coatings, the
substrate must be free from all adhesion
inhibiting substances such as oil, grease,
release agents, as well as cement laitance and
dust.
Failed existing coatings are to be removed.
Sound coatings should be tested for
compatibility and pull off strength.
Permissible residual moisture content will vary
according to the coating / screed system to be
applied. Maximum, 6% for epoxy resin systems and
not more than 4% for polyurethane system.
Resin based systems should not be used where
rising damp occurs. Magnesite and anhydrite
screeds lose their strength with water. In such
cases only hydraulic systems, open to diffusion
should be used.
SURFACE PREPARATION
The most common surface preparation techniques
are as follows:
DUST FREE VACUUM SHOT-BLASTING : By this method
steel shot is propelled at high velocity onto
the floor, abrading the surface. The abrasive
and cement laitance is drawn by vacuum and
separated. The debris is collected and the
abrasive cleaned and recycled. As the process is
virtually dust free. It often allows production
to continue on the shop floor. Depending on the
machine type used, a large variety of surface
textures is obtainable. Weak or poor screeds can
lead to a large amount of debris.
HIGH PRESSURE POWER WASHING : Here water is
blasted at more than 400 bar through rotating
nozzles onto the surface. By this method all
dirt, laitance and contaminants are washed off
the surface. Trials should be held to identify
blast pressure.
Allowance must be made for drainage of used
water / debris. Floor must be allowed to dry
before application of coating materials.
SHOT-BLASTING : This is a manually operated
system whereby quartz free solid abrasives are
blasted onto the surface with high air pressure.
A very high level of dust is generated here. An
alternative to minimize the dust level is the
addition of water, which is then termed wet
shot-blasting.
The debris and water must be manually vacuumed
afterwards.
FLAME BLASTING : After flame- blasting the
surface must be further treated with high
pressure water blasting (pressure greater than
100 bar), or air pressure blasting in order to
remove fire damaged aggregates.
This method is particularly relevant to
organically contaminated old floor (e.g. oil).
GRINDING / SCABBLING : A scabbler operates on
the principle of rotating steel grooving
elements. The applied scabbling must be suited
to the concrete surface and should not transfer
undue vibration or stress onto the structure.
The depth of scabbling should not exceed 5mm and
the scabbling strips should not overlap by more
than 5 cm. in general it produces a ribbed
texture.
After all surface preparation measures the
surface is to be swept for remaining dust and
loose particles. This is best achieved with an
industrial vacuum cleaner.
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