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A
polyurea spray elastomer system for capping landfills has
recently been developed. Specifically it provides a seamless
cap, which prevents water infiltration and can increase landfill
capacity.
Artwork
courtesy of ITW Irathane, UK |
| The
system is a two component, 100% solids, polyurea spray elastomer
that offers the following features as a landfill cap: |
- Provides a monolithic,
seamless membrane
- Increases landfill
capacity
- Bonds to soil
and almost any underlying support material
- High strength
and elongation values to handle settling
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- Exhibits characteristics
between HDPE and VLDPE, without seams
- Directly applied
to surface obstructions such as vent pipes
- High interface
friction angle
100% solids, no volatile organic compounds (VOC’s)
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- Easy to repair
damaged areas, including areas of differential settling
- Absorbs and
dissipates stress, including thermal cycling
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| This
polyurea spray elastomer consists of an isocyanate terminated
prepolymer reacted with an amine terminated resin. The liquids
are pumped by a two component dispensing unit at 2,000 psi
and 155oF and sprayed through a mechanical purge
gun in a fan-shaped pattern. They react almost immediately
with a gel time of 3 seconds and tack free time of 6 seconds.
The elastomer can be walked on in minutes. The application
can be made by hand or with automated equipment, using a transversing
spray gun.
Application consists
of applying a levelling soil over the filled landfill. Next,
a non-woven polypropylene geotextile fabric is rolled into
place. The spray elastomer is used to "seam" the
geotextile. The geotextile is then sprayed with an average
thickness of 100 mm with the polyurea spray elastomer. Drainage
material and topsoil can then be applied over the seamless
membrane. |
| The
cured elastomer will have the following physical properties: |
| Tensile
Strength |
20
MPa |
ISO
37 |
| Elongation |
450
% |
ISO
37 |
| Tear
Strength |
78.8
kN/m |
ISO
34 -1, die C |
| Puncture
Resistance |
109.4
kN/m |
ASTM
D 4833* |
| Index
Puncture Resistance |
323.8 |
FTMS
101 C* |
Water
Vapour Transmission
(g/m²/24 hours) |
42 |
ISO
6179 |
| Direct
Shear: |
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ISO
6179 |
Elastomer onto soil
Elastomer/Geotextile onto soil |
38o
37o |
ISO
6179 |
Linear
shrinkage @ 2.5mm DFT
600 x 600 sheet |
1.1% |
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| Hardness,
Shore A |
90
95º |
ISO
7619 |
| Coverage
Rate |
2.44kg/m²
2.5mm dft |
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*
No direct EN or ISO standard comparable with US standards
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| This
polyurea spray elastomer produces a smooth, durable, seamless
hydraulic barrier. It has been analysed by an independent educational
institution and found to be "very suitable for a landfill
cap application". |
| Advantages |
- Monolithic,
SEAMLESS cover prevents water penetration
- Elimination/Reduction
of clay cover, increasing capacity
- Eliminates need
for heavy equipment or extensive labour
- Ideal for differential
settlement applications
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- Combats freeze/thaw
problems and desiccation cracks
- Conforms to
subgrade condition, gripping surface and allowing an increase
in friction angle
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- Bonds directly
to leachate removal sump riser, preventing water penetration
- Physical properties
comparable to PVC and VLDPE
- Improved application
rates
- Cost competitive
with current capping technologies
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| SPRAYED
ELASTOMER SYSTEM APPLICATIONS |
CORROSION
PROTECTION |
WATERPROOF
MEMBRANES |
ABRASION
RESISTANCE |
BARRIER
COATINGS |
Manhole Rehabilitation
Tank Lining
Pipe Lining
Effluent stacks
Concrete coatings |
Pond/ditch linings
Foundation coatings
Landfill cover liners
Bridge deck coating
Utility chases |
Pick-up/load bed liners
Storage/shipping container
Dumpster
Tank coating
Tumblers |
Secondary containment
Asbestos encapsulation
Freezer lining
Floor/wall/ceiling coating
Maintenance coatings |
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| Advantages |
- Seamless
- Strong adhesion
- Tough
- Durable
- Algae-resistant
- Colour Options
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- Fast curing
- Puncture resistant
- 100% solids
- Flexible
- Abrasion resistant
- Chemical Resistant
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- Versatile
- Moisture insensitive
- Glass Reinforcement
- Cost competitive
- Easy-spray application
- Texture Variability
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