Waterproofing With GCLs
Volker Streffing-Hellhake
NAUE GmbH & CO. KG
© 2011 NAUE GmbH & Co. KG · www.naue.com
Why basements are waterproofed
• Stop surface water which perculates into
the ground from entering the basement
• Stop perched water from entering the
basement
• Stop ground water from entering the
basement from the bottom
• Stop radon or methane gas from entering
the basement.
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Grades of Waterproofing
• The grade of waterproofing depends upon
the usage in the basement.
• If the basement will be used as a car park
(the cars also bring in water when it is
raining/snowing outside) then the
efficiency of the waterproofing does not
have to be so good compared to
basements containing shops or other
valuable goods/machines.
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Lining systems for waterproofing
basements of buildings
•
•
•
•
•
•
Special Concrete
Bitumin sheets (GBR-B)
Coatings
PVC/TPO plastic liners (GBR-P)
Bentonite liners (GCLs) (GBR-C)
Combination of the above.
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Geosynthetic Clay Liners
(GCLs)
In the EU, GCLs are now officially
abbreviated to
Geosynthetic Barriers – Clay: GBR-C
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The Bentonite in GCLs
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• The bentonite in GCLs
–High swelling sodium bentonite
–sodium improved calcium bentonite
(also called sodium bentonite)
–calcium bentonite
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The k value of sodium bentonites is significantly lower
(better) than calcium ones.
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What is Bentonite?
Mg 2+) => negative unbalance
Substitution (Si 4+ Al 3+ ; Al3+
compensated partly by exchangeable cations, e.g. Na+ which hold the
flakes electrostatically together.
Calcium
Bentonite
Sodium Bentonite
+
+ -
- - - - - - - - - - - - - - - + - - - - - - - - - - - - - - - - +
- - - - - - - - - - - - - - - +
+
- - - - - - - - - - - - - - - Na
+
Na
Na
+
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
- - + - - +
Ca
- -++
- - -
- - - - - - - - - - - - - - - - - - - - - - - - - +
+
Ca
- - - - - - - - - +- - - +
- - - - - - - - - - - - -
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The bentonite in GCLs
• What is better?
–High Swelling sodium bentonite
–Sodium enriched calcium
bentonite (also called sodium
bentonite)
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Comparision of Bentonites
Swell Index is a quick way to identify
the bentonite quality for GCLs
High swelling
sodium bentonite
Bentonite presently
used in Chinese GCLs
Calcium bentonites
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Bentonite can be improved by adding
special polymer additives in about 1%
quantity.
How can 1% additives be added evenly
to the bentonite?
Most polymer additives are toxic.
Austrian Guidelines do not allow the use of
additives in GCLs for waterproofing
applications.
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© 2011 NAUE GmbH & Co. KG · www.naue.com
Self-healing Performance of GCL s with High
Swelling Sodium Bentonite
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The methods of joining the
components together.
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GCLs
• Method of joining the components
together:
–needle punching (Bentofix)
–sewing
–heat bonding
–gluing
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The reinforcement of GCLs by a needle
punching process
Top non-woven geotextile
The bentonite layer
The bottom carrier geotextile
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The Bentofix Peel Test
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The Bentofix Peel Test
You can see the fibres
breaking as the Bentofix
BFG 5000 is pulled
apart.
There are about 2.5 million fibre bridges each m²
with Bentofix
The high force required
to break these fibre
reinforcements is
causing the geotextile to
“neck”.
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Why GCL overlaps can fail
The main reason for overlap
failure is not enough
bentonite to seal the nonwoven component.
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Most GCLs have at least
one needle punched
geotextile component.
Needle punched
geotextiles are very
porous
At overlaps the needle
punched geotextile
needs to be sealed with
extra bentonite
The result of improper GCL overlaps
The Results of Improper
Sealing of GCL
Overlaps
The total discharge of the liquid
through such incorrect
overlaps per day is around
4.4 m³/day (1604 m³/year) in
this example of a 1000 m²
pond, depth 1 m.
This is very disturbing!
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Some GCLs have extra bentonite
as a second layer impregnated
into the needle punched geotextile
The unique Bentofix BFG 5000
GCL is manufactured with
additional bentonite powder
impregnated into the top
geotextile covering the complete
roll area.
There is no need for any extra
bentonite to be placed in any
overlap area on site.
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Bentofix® BFG5000 as Waterproofing
How it works
With a fully bentonite impregnated nonwoven as top layer
Concrete wall
Bentofix BFG5000
as waterproofing
Bentonite moves
into cracks
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GCLs are robust enough to survive rain
during installation.
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Installing GCLs for
waterproofing of underground
structures
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Reinforced concrete floor slabs
Vertical Walls
Concrete Caissons
Sheet piles
Storage & Repairs
Final Remarks
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Sealing of reinforced concrete floor
slabs
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Sealing of reinforced concrete floor
slabs
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Subgrade / mud slab
Concrete placement
Level measurements
Concrete spreading
Overlap fixing
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One way to keep the
overlap areas clean.
Another way is to fold
over the GCL on itself.
Make sure when you
open the fold later, the
second piece covers the
fold.
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Sealing of foundation piles
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Sealing Penetrations in base slab
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Sealing Penetrations in base slab
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The GCL is a system
• 1st part of the system:
• The surface upon which the GCL will be installed must
have the right form: even, no sudden differences in
height, no small cavities, no standing water, suitable
environment.
• 2nd part of the system:
• the proper installation of the GCL
• 3rd part of the system:
• The GCL must have a surcharge to stop uncontrolled
hydration e.g. a concrete layer or soil pressure
(minimum 6 kN/m²)
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Installation against shuttering
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How to stop the concrete getting into the
overlaps:
Fresh concrete
leakage
GCL
Staples are used
sometimes
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overlap
An alternative, which we
have found to be technically
good, is to use a flexible
metal strip with holes, fixed
with the Hilti gun
•
Details to consider in the base slab.
These should be designed before the
works starts!
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Installation on vertical walls
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Vertical Walls
Wall Joints
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Waterstops are required at joints.
Between different
concrete pours
Between concrete and
sheet piles…….etc.
We supply Bentostrip only.
© 2011 NAUE GmbH & Co. KG · www.naue.com
When exposed on vertical walls for a long
time the GCL needs to be protected from
rain.
Bentofix X2 BFG 5300
Voltex CL
Etc.
© 2011 NAUE GmbH & Co. KG · www.naue.com
Advantages
• Resistance against desiccation
• Protection against ion exchange
• Reduction of root penetration
• Gas, radon barrier
• k-value improvement
• Improves additionally the good
bentonite erosion stability at high water
pressures and gravel soils
42
© 2011 NAUE GmbH & Co. KG · www.naue.com
Advantage
• Resistance against desiccation
• Protection against ion exchange
Disadvantage
- Susceptible to damage during
installation
- low interface friction
• Reduction of root penetration
• Gas, radon barrier
• k-value improvement
• Improves additionally the good
bentonite erosion stability at high
water pressures and gravel soils
43
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How do you create a hole in the ground without
causing damage to the buildings next door?
Sheet piles
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Concrete piles: Caissons
Concrete Caissons
Sealing of concrete base
slabs
Sealing of vertical walls
Concrete Caissons
Storage & Repairs
Final Remarks
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Concrete Caissons
0.60 m
> 90 °
> 10 cm
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Connecting caisson wall to
bottom sealing.
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Sometimes the contractor has to improve the
surface before the waterproofing liner can be
installed.
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Points to watch out for:
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Concrete Caissons
Fixing
Patching
(with e.g. Hilti shot nails
(with e.g. stapling)
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Finished wall
Sealing sheet piles
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This can be a cheaper solution (less
fixing points), but the structural stability
of the wall should be looked at.
Polystyrene
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Sealing sheet piles
Void filled using metal
plate and gravel.
Close up of the special
washer to stop the nail
from penetrating the
Bentofix. Special
ammunition is required.
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Final Remark
If it´s leaking ......
... it´s probably not a GCL…..
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Or it is bad installation!
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Thank you for your kind attention.
[email protected]
+49 5743 41 582
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