Why basements are waterproofed - WordPress.com...2012/03/15 · Grades of Waterproofing • The grade of waterproofing depends upon the usage in the basement. • If the basement

© 2011 NAUE GmbH & Co. KG · www.naue.com

Waterproofing With GCLsVolker Streffing-HellhakeNAUE GmbH & CO. KG


Why basements are waterproofed

• Stop surface water which perculates intothe ground from entering the basement

• Stop perched water from entering thebasement

• Stop ground water from entering thebasement from the bottom

• Stop radon or methane gas from enteringthe 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 israining/snowing outside) then theefficiency of the waterproofing does not have to be so good compared tobasements containing shops or othervaluable goods/machines.


Lining systems for waterproofingbasements of buildings

• Special Concrete• Bitumin sheets (GBR-B)• Coatings• PVC/TPO plastic liners (GBR-P)• Bentonite liners (GCLs) (GBR-C)• Combination of the above.




Geosynthetic Clay Liners (GCLs)

In the EU, GCLs are now officially abbreviated to

Geosynthetic Barriers – Clay: GBR-C


The Bentonite in GCLs




• The bentonite in GCLs–High swelling sodium bentonite–sodium improved calcium bentonite

(also called sodium bentonite)–calcium bentonite


The k value of sodium bentonites is significantly lower (better) than calcium ones.




What is Bentonite?

- - - - - - - - - - - - - - - -+Na

- - - - - - - - - - - - - - - -+ +

Na+- - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - -+ +

+Ca+

- - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - -

+Ca+

- - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - -+ +

+ +- - - - - - - - - - - - - - - -+

Na

- - - - - - - - - - - - - - - -+ +

Substitution (Si 4+ Al 3+ ; Al3+ Mg 2+) => negative unbalance compensated partly by exchangeable cations, e.g. Na+ which hold the flakes electrostatically together.

Sodium Bentonite

Calcium Bentonite


The bentonite in GCLs

• What is better?–High Swelling sodium bentonite–Sodium enriched calcium

bentonite (also called sodium bentonite)




Comparision of Bentonites

High swelling sodium bentonite

Bentonite presently used in Chinese GCLs

Calcium bentonites

Swell Index is a quick way to identify the bentonite quality for GCLs


Bentonite can be improved by adding special polymer additives in about 1%

quantity.

How can 1% additives be added evenly to the bentonite?

Austrian Guidelines do not allow the use ofadditives in GCLs for waterproofing

applications.

Most polymer additives are toxic.





Self-healing Performance of GCL s with High Swelling Sodium Bentonite




The methods of joining the components together.


GCLs• Method of joining the components

together:–needle punching (Bentofix)–sewing–heat bonding–gluing




The reinforcement of GCLs by a needle punching process

Top non-woven geotextile

The bentonite layer

The bottom carrier geotextile


The Bentofix Peel Test




You can see the fibres breaking as the Bentofix BFG 5000 is pulled apart.

The high force required to break these fibre reinforcements is causing the geotextile to “neck”.

The Bentofix Peel Test

There are about 2.5 million fibre bridges each m² with Bentofix


Why GCL overlaps can fail

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 main reason for overlap failure is not enough

bentonite to seal the non-woven component.




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!


Some GCLs have extra bentoniteas 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 anyoverlap area on site.




Bentofix® BFG5000 as WaterproofingHow it works

Concrete wallBentonite movesinto cracks

Bentofix BFG5000as waterproofing

With a fully bentonite impregnated nonwoven as top layer


GCLs are robust enough to survive rain during installation.




Installing GCLs for waterproofing of underground

structures


Reinforced concrete floor slabsVertical WallsConcrete CaissonsSheet pilesStorage & RepairsFinal Remarks




Sealing of reinforced concrete floorslabs


Sealing of reinforced concrete floorslabs




Subgrade / mud slab

Level measurements

Overlap fixing

Concrete placement

Concrete spreading


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.




Sealing of foundation piles


Sealing Penetrations in base slab




Sealing Penetrations in base slab


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)




Installation against shuttering


How to stop the concrete getting into the overlaps:

An alternative, which we have found to be technically

good, is to use a flexible metal strip with holes, fixed

with the Hilti gun

•

Fresh concrete

Staples are used sometimes

GCL

leakage overlap




Details to consider in the base slab.These should be designed before the

works starts!


Installation on vertical walls




Vertical Walls

Wall Joints


Waterstops are required at joints.Between different concrete pours

Between concrete andsheet piles…….etc.

We supply Bentostrip only.




When exposed on vertical walls for a long time the GCL needs to be protected from

rain.

Bentofix X2 BFG 5300

Voltex CL

Etc.


42

Advantages

• Resistance against desiccation

• Protection against ion exchange

• Reduction of root penetration

• Gas, radon barrier

• k-value improvement

• Improves additionally the goodbentonite erosion stability at high waterpressures and gravel soils




43

Disadvantage- Susceptible to damage during

installation

- low interface friction

Advantage

• 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


How do you create a hole in the ground withoutcausing damage to the buildings next door?

Sheet piles Concrete piles: Caissons




Concrete Caissons

Sealing of concrete baseslabsSealing of vertical wallsConcrete CaissonsStorage & RepairsFinal Remarks


Concrete Caissons

0.60

m

> 10 cm

> 90 °




Connecting caisson wall to bottom sealing.


Sometimes the contractor has to improve thesurface before the waterproofing liner can be

installed.




Points to watch out for:


Concrete Caissons

Fixing Patching Finished wall(with e.g. Hilti shot nails (with e.g. stapling)




Sealing sheet piles


This can be a cheaper solution (lessfixing points), but the structural stability

of the wall should be looked at.

Polystyrene




Sealing sheet piles

Void filled using metalplate and gravel.

Close up of the specialwasher to stop the nailfrom penetrating theBentofix. Special ammunition is required.


Final Remark

If it´s leaking ......

... it´s probably not a GCL…..




Or it is bad installation!


Thank you for your kind attention.

[email protected]

+49 5743 41 582



mailto:[email protected]

Why basements are waterproofed - WordPress.com...2012/03/15 · Grades of Waterproofing • The grade of waterproofing depends upon the usage in the basement. • If the basement

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