Volume 7, no. 13 - Colbond Geosynthetics

Volume 7, no. 13 

N 

GEOSYNTHETICS W 

S 

Good drainage takes 

the pressure off 

of Alpine 

engineering

Volume 7, no. 13 

N 

GEOSYNTHETICS W 

S 

Good drainage takes 

the pressure off 

of Alpine 

engineering 

September 2002 

Colophon 

Geosynthetics News is a publication of 

Colbond Geosynthetics for its business 

relations all over the world. 

Geosynthetics News appears in English, 

German and Spanish. 

Editors: 

Winny van den Tempel 

Sietske Buiskool Leeuwma 

Hannah Hübner 

Editorial contributions: Sam Garrett 

Editorial address: 

Colbond Geosynthetics 

P.O. Box 9600 

6800 TC Arnhem 

The Netherlands 

Tel. +31 26 366 4561 

Fax +31 26 366 5812 

E-mail: geosynthetics@colbond.com 

Internet: 

www.geosynthetics.colbond.com 

® = registered trademark 

Printed in the Netherlands on recycled 

paper. 

Articles or illustrations may be copied in other 

publications subject to Colbond’s prior 

authorization in writing and acknowledgement 

of the source. 

Publication of articles by authors who are not in 

the service of Colbond shall be for the 

responsibility of the authors concerned. 

2 Colbond Geosynthetics News 13 - 2002 

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From the editors 

Cover story 

Good drainage takes the pressure off of Alpine engineering 

Column 

by Wim Voskamp 

Will bypass bring mountain idyll back to Giswil 

Polymer expertise and know-how: key ingredients for tailor-made 

product development for AlpTransit project 

Enkamat ® & Enkadrain ® : high-performance flexibility 

Underslating/drainage composite layers in metal roofings 

Short News 

Enkagrid ® PRO picked for Floriade 

Enkagrid ® PRO and Enkamat ® a fruitful combination 

Mekastone and Enkagrid support World Cup Soccer 2002 

Worldwide network 

Colbond Geosynthetics is a supplier of quality products for civil engineering applications. Based 

on polymer technology, these products are used in drainage, erosion control, landfill application and 

soil improvement. The company has a global network of specialists at its disposal. 

Colbond’s materials are produced and supplied in accordance 

with the ISO 9001:2000 quality assurance standard. 

Contents

Dear Readers, 

From the editors 

Geosynthetic materials are often “silent partners”. These 

materials do their work precisely in those places where the 

general public - and often even the end-users - don’t see them. 

Preventing erosion, stabilizing embankments, draining and 

diverting water pressure are just a few of the very important, but 

often largely unnoticed, tasks our products fulfil. 

At the same time, these silent partners are often an essential part 

of a silent revolution. In projects around the world, the unique 

properties of reliable Colbond Geosynthetics’ products have 

offered solutions that would not have been possible with 

traditional materials. 

This issue of Geosynthetics News is dedicated to the role of our 

materials in the demanding area of tunnel construction. Here 

you’ll read about exciting new projects currently underway in 

Switzerland. And about how, in combination with geomembrane 

waterproof liners, our geosynthetics (and geospacers in 

particular) are allowing new design freedom, lower maintenance 

and greater tunnel stability. 

So the next time you steer the family car through one of these 

modern marvels of engineering, be sure to think of us. Because 

you may not see our products - but chances are, they’re there. 

Your editorial team 

Colbond Geosynthetics News 13 - 2002 

3

Cover story 


Good drainage takes the 

pressure off of Alpine 

engineering 

“Tunnel-builders are a rare breed.” The gentleman manning the stand 

at the STUVA exhibition (taking place end of last year) in Munich 

takes a sip of his coffee and looks around. “Did you know that they 

name their tunnels after women, but that it’s considered bad luck for 

a woman to enter the tunnel before it’s finished? Sort of like… 

submarine commanders.” 

Somehow what he’s saying isn’t too hard to believe. Walking around 

the floor of Europe’s biggest tunnel-building exhibition in the 

Bavarian capital’s Messestadt hall is a bit like waking up to find 

yourself in a novel by Jules Verne. 

Massive five-megawatt tunnel-boring machines, with cutting heads 

made of space-age material that can grind through granite for days 

on end. 

Caissons the size of houses that can be sunk into mud and 

connected under sixty meters of water. The highest high-tech going, 

in other words. And all of it surrounded by that rush of excitement 

we’ve all had as children, when the tunnel we burrowed under the 

sandcastle finally emerged on the other side, and our fingers touched 

fresh air. 

Romantic? Probably. Challenging? Absolutely. Because what most of us don’t 

realize, as we cruise at 100 kilometers per hour hundreds of meters below the 

mountain slopes, are the incredible forces that have to be dealt with in order to 

build a modern transport tunnel. Or the stringent safety requirements that have 

to be met by every piece of material in one of these marvels of engineering. 

All things we do not realize, perhaps… until things go wrong. 

The tragic fires in the tunnels at Mont 

Blanc and St. Gotthard, however, are 

still fresh in the minds of European 

travelers and transport professionals. 

While, years later, the economic 

effects of the almost total 

deregulation of the transport 

infrastructure on both sides of those 

crucially important tunnels are still 

being felt.

Forces at play 

Fire safety is a very important 

parameter in tunnel construction. 

Today’s tunnel materials are therefore 

subject to very stringent fireproofing 

requirements. But the very makeup of 

the Earth’s crust through which these 

transport tubes are bored or blasted, 

and the forces at play in those layers 

of rock, pose hazards and challenges 

all their own. A perfect example is 

found in one of the biggest tunnel 

ventures ever: the NEAT (New Alpine 

Rail Axes) project. 

Being billed even now, in the first 

years of the new millennium, as “the 

rail-transport project of the century”, 

the NEAT plan is being supervised by 

Switzerland’s AlpTransit authorities 

and is breathtakingly ambitious. 

Consisting of two gigantic and 

roughly parallel base tunnels, the 

Lötschberg and the Gotthard, NEAT 

will create new high-performance rail 

links on the north-south axes through 

Switzerland. Among other things, the 

project is creating the world’s longest 

rail tunnel for passenger and goods 

transit traffic - 57 kilometers from 

Erstfeld in central Switzerland to 

Bodio in the Italian-speaking south. 

This section alone, scheduled for 

completion in 2012, is expected to 

cost more than 10 billion Swiss francs 

(US $5.8 billion). 

That the art of tunneling today has a 

pronounced high-tech element is 

illustrated by AlpTransit’s use of GPS 

satellite communication, in 

combination with gyroscopic (nonmagnetic) 

compasses and computer 

simulation, to guide surveyors 

working at the mountains’ heart. 

Because tunnels of this length must 

be built in stages, often starting at 

points dozens of kilometers from 

each others, pinpoint navigation is 

essential. Still, many were amazed 

when the Swiss authorities recently 

announced that the current state of 

alignment between the portals at the 

north and south ends of the 57kilometer 

Gotthard Base Tunnel had 

achieved an accuracy of less than 

one centimeter! 

Cover story 

Soaring demands 

With the extension of its railway 

infrastructure, and the use of highspeed 

freight and passenger trains, 

Switzerland plans to be in a position 

to meet soaring demands on its 

international transport grid. A study 

recently carried out on behalf of the 

European Commission showed that 

by 2010, this traffic through 

Switzerland will have increased by 

around 75% above 1992 levels. One 

goal of the NEAT project, therefore, is 

ultimately to almost halve transport 

times from north to south - estimates 

are that, by the time the project is 

completed, travel times for passenger 

trains from Zurich to Milan will have 

shrunk from three hours and forty 

minutes today to a mere two hours 

and ten minutes. 

But even more amazing than length, 

expense or speed, perhaps, is the 

depth at which the tunnels in the 

NEAT project are being built. 

Because the tunnels are being bored 

and blasted much closer to the base 

of mountains than ever attempted 

before (at the most extreme point, 

there will be more than 2,000 meters 


5

Cover story 

of mountain on top of the tunnels), 

trains will be able to go straight 

through, rather than having to wind 

their way up and down the sides of 

the mountains on the approaches. 

But, as a famous soccer analyst once 

said, every advantage has its 

disadvantage. One disadvantage of 

the relatively flat trajectory of the 

Lötschberg and Gotthard tunnels is 

that massive rock formations above 

the work exert more pressure than 

that encountered on more 

conventional tunnels: tricky rock 

layers can shift and jam drilling 

equipment. In addition, says Peter 

Zwicky of Zurich’s Ingenieurbüro für 

Abdichtungstechnik, a consultant to 

AlpTransit, rock temperatures there 

can rise to as high as 40°C. And, 

equally demanding for the materials 

used is the fact that the water 

pressure from strata overlying the 

Gotthard base tunnel has been 

estimated at as high as 100 bar. 

6 Colbond Geosynthetics News 13 - 2002

High-pressure cascade 

Tunnel shells alone, of course, 

cannot evenly distribute that kind of 

pressure, and would actually be 

destroyed by it. The recurring 

problem, until now, has been how to 

ensure that this high-pressure 

cascade finds an outlet well away 

from the inner tunnel walls. 

Traditionally, tunnel-builders use a 

waterproof liner between the rough 

cement-covered rock walls and the 

inner shell. But it is very important 

that the liner remains intact in order 

to keep water off of the shell itself. 

That is where geotextiles come in. 

“Geotextiles are not only used to 

protect the liner from perforations,” 

Zwicky says, “but also create a 

hollow drainage space between the 

shotcrete and the liner. That serves a 

very important function in diverting 

water pressure from the inner shell. 

The problem is that the pressure from 

the shuttered concrete shell on the 

inside and the pressure coming from 

the outside can press normal 

drainage material flat, so the water 

cannot escape. With all the problems 

that would entail. Even under 

pressure, though, geotextiles like 

special Enkadrain tunnel types 

provide a transmissivity of almost 200 

times that of normal drainage 

material.” 

All well and good, of course, but at 

temperatures like those found in the 

Gotthard base tunnel, the use of 

thermoplastic geotextiles in 

combination with a thermoplastic 

waterproof liner would only make the 

problem worse. This problem was 

therefore one of those recently 

addressed during the specifying 

rounds for the more westerly 

Lötschberg base tunnel. 

Cover story 

There, AlpTransit’s preliminary testing 

indicated that not only pressure, but 

also the combination of heat and the 

caustic chemical makeup of the rock 

itself - and therefore of the water 

seeping through it - called for 

construction materials unlike those 

commonly applied in tunnel 

construction. 

Water from the rock 

“Rock water,” Zwicky says, “can have 

properties that affect the resistance of 

geotextiles. These can include an 

extremely high pH, or the presence of 

carbonic acid, microbes, etc. The 

geotextiles used must therefore be 

resistant to all these things.” 

The first round of testing in the year 

2000 perfectly illustrated his point. 

The standard materials submitted by a 

host of manufacturers, proved, without 

exception, incapable of surviving the 

hostile climate to which they would 

later have to be submitted. Despite 

the expense involved in a second 

round, a number of manufacturers 

returned to their designers with an 

even stricter set of parameters. 

In the case of Colbond Geosynthetics, 

this meant taking a good hard look at 

items like chemical resistance, fire 

resistance and oxidation - the latter as 

a result of the abnormally high 

temperatures measured in the 

Lötschberg base tunnel. 

“The Enkamat material we had tested 

again in the second round,” says 

Colbond Geosynthetics Sales 

Manager Karl Wohlfahrt, “was based 

on a core and filter made from 

polypropylene. This material actually 

exceeded the drainage demands 

placed by the specifiers, and also 

significantly reduced the accelerated 

aging of the material at higher 


7

Cover story 

temperatures. And, almost needless to say, it passed the 

test.” 

Colbond Geosynthetics, in combination with liner 

manufacturer Sika, is currently a front-runner to obtain the 

contract for supplying some 430,000 square meters of 

drainage material for the first section of the Lötschberg. “We 

have by now managed to get the first part of the order,” 

says Wohlfahrt, “and I trust that this will be the case for the 

overall order, too. This could be a good reason for important 

customers like Alp Transit to employ these products in 

future projects as well - and this is not only true for NEAT, 

but also for other tunnel construction projects worldwide.” 

8 Colbond Geosynthetics News 13 - 2002

Column 

“The world 

changes rapidly” 

is an observation that is probably as 

old as the world itself. Progress, as a 

result of change, has widened people’s 

horizon and made the world 

increasingly accessible. Fifty years ago 

a journey from Europe to Asia took 

three weeks by boat. This was the only 

means of conveyance to travel there at 

the time. My first flight to Asia, some 

20 years ago, took about 24 hours. 

Today’s non-stop flights only require 

half of that time. 

Communications between the 

continents show a similar pattern. 

The days of forwarding letters by boat 

do not lie far behind us. 

Airmail was quite an improvement, not 

to mention telex. 

The latter provided a more direct 

contact, though various steps were 

needed between writing the message 

and its receipt received by the 

addressee. Different time zones were 

additional time obstacles. 

The fax machine offered new 

possibilities and quickly evolved from a 

relative ‘time-consuming’ 

communication tool to a convenient 

and widely used facility. 

Highly advanced yesterday, today the 

fax is obsolete and virtually 

superseded by the almost unlimited 

possibilities of electronic mail. 

Texts, pictures, sounds - you name it - 

everything can be transmitted via email 

in a jiffy. And, thanks to cell phones 

everybody can be reached, whenever 

and wherever. 

Additionally, the electronic highway has evolved from a cumbersome and 

rather unreliable novelty into the backbone of many a firm’s communications 

and information systems. 

The advantages are numerous and the impact of progress on the modern 

business environment is undeniable. 

Does all this make us happier, and does it really improve the quality of work 

and communications? 

Yes, it actually does, at least as long as it is used properly. 

A tool should never be used as a target in itself. 

The proper use of a tool always requires a certain discipline. The new tools 

are no exception to this rule. 

Communication remains what is, a process by which information is 

exchanged between individuals through a common system of symbols, signs 

or behavior. The system may change, the principle, however, does not. 

Finding over 150 emails after returning from a couple of days out of the office 

does not have anything to do with communications. It is frustration caused by 

overkill resulting from the unlimited forwarding of information. 

We, users of the system, all have our own responsibility in making it work the 

way it was meant to. 

This not only implies for better-targeted communications at the right time and 

with the right frequency but it also means that communication efforts should 

be placed into the right perspective by comparing the usefulness of 

conventional media with electronic ones. This could very well result in 

reconsideration of an established approach. 

Could the role of such printed communication tools as brochures, data sheets 

and magazines partly or entirely be taken over by an electronic alternative? 

Colbond Geosynthetics already successfully provides a substantial part of its 

information via the Internet and on CD-Rom. 

Could this also be extended to our magazine Geosynthetics News? 

Would the advantages outweigh the limitations? 

Anticipating the future obviously involves careful consideration of all ‘pros’ 

and ‘cons.’ 

The world changes, people change, communication changes. 

Whether Geosynthetics News will be changed and how, is still subject to 

reflection. We will keep you posted. 

Wim Voskamp 


9

Will bypass bring 

mountain idyll back 

to Giswil? 


Past Oerlikon Stadium, the highway south pops in 

and out of the shade of a seemingly endless series 

of cut and cover tunnels, then stretches out along a 

chain of long lakes mirroring the rocky peaks 

around. It’s the stuff picture postcards are made of. 

For the good people of the town of Giswil, 

Switzerland, however, peace and quiet may only now 

be returning. For this town of not quite 3,500 souls is 

located on the main arterial road between the 

metropolis of Zurich and the city of Interlaken. 

Convenient enough for the tens of thousands of 

visitors who come each winter to ski on the 

surrounding 6,000-foot slopes, but something less 

than a blessing for the citizens themselves. 

The beginning of the solution started, 

however, when the authorities of 

Obwalden Canton received approval 

to build a two-kilometer bypass tunnel 

to lead the N8 national highway 

around Giswil. The project, estimated 

at some 121 million Swiss francs, 

started in 1997 and is scheduled to 

be open to traffic in the course of 

2003. 

Although the tunnel is not yet open to 

the public, construction machinery 

now drives in and out of the south 

portal, where the first breakthrough 

came in February of 2000. Inside, the 

tunnel itself is a model of modern 

engineering. When completed, the 

inner shell, with a diameter of a little 

over ten meters, will house a twolane 

highway with a maximum speed 

limit of some 85 kilometers an hour 

and a gradient of 2.5%. To get there, 

the builders used more than 50,000 

man-hours and 180 tons of 

explosives to mine their way through 

sandstone, chalk and limestone 

formations. Close to the north portal, 

the almost vertical layers of 

sedimentary rock produce a flow of a 

few hundred liters of water per minute 

in the vicinity of the tunnel entrance.

Today, most of the 2,000 meter 

gallery has been covered in a 25 - 30 

centimeter thick layer of ‘shotcrete’ - 

liquid concrete sprayed onto the raw 

rock walls - and a large portion is 

already equipped with bright orange 

PVC membrane. Outside the winter 

sun is bright, but here in the cavern 

men are working in constant dusk, 

air-testing the welds on the 

waterproof liner. 

“The membrane used in tunnels 

almost always has a colored signal 

front layer and usually a black 

backing,” explains Rudi Kubli of 

Schoellkopf AG, Colbond 

Geosynthetics’ Swiss distributor. 

“That makes it easier to check 

visually for cuts and punctures.” 

Behind the PVC at Giswil is some 

45,000 square meters of Enkamat ® 

three-dimensional geospacer, 

attached to the rock wall at one-meter 

intervals by means of steel nails and 

PVC washers. Liner and Enkamat 

form a ‘sandwich’ when the liner is 

heat-welded to the washers. Valves 

located at strategic points in the liner 

allow air to be pumped behind the 

PVC to make sure the ‘sandwich’ is 

truly water-tight. 

“Tunnels are a major infrastructural 

investment,” Kubli says. “You can’t 

afford to close down a tunnel and fix 

the walls every few years. So the 

highest safety combined with 

extremely low maintenance is a very 

important criterion for specifiers. 


11


Cross-section tunnel: 

rock 

gunite/shotcrete 

Enkamat/Enkadrain 

liner 

inner-wall 

lateral drains 

main drains

“One way to keep tunnel walls intact 

is to ensure that water seepage is 

ruled out. And one major function of 

Enkamat is to protect the waterproof 

liner, and so the entire tunnel, against 

leakage. Add to that the higher 

discharge capacity of Enkamat and 

its much lower susceptibility to 

clogging, and you have the best 

system available for protecting the 

inner shell of the tunnel and for 

leading water into the tunnel drainage 

system.” 

Here at Giswil, 80-centimeter-high 

concrete “benches” have been built 

on both sides of the tunnel floor, 

serving to protect the parallel drains 

which themselves are covered with a 

single layer of Enkamat. The 

geospacer’s lack of sensitivity to 

particle or mineral clogging means 

that seepage from the rock face and 

seepage from the stream high above 

the north portal of the Giswil tunnel 

can continue to pass into the 

Enkamat. In chalky surroundings like 

Giswil, this is crucial to keeping the 

tunnel dry. 

For builders, one of the prime 

advantages of Enkamat geospacers 

is how easily they can be adapted to 

individual projects. “We offer 

Enkamat in different breadths, of 

course,” says Colbond Geosynthetics 

Sales Manager Karl Wohlfahrt. “The 

most usual being the 3.85 m wide 

rolls. But even more importantly, part 

of our service is to deliver the right 

lengths to the site. If they want 24meter 

lengths, they can get it. If they 

want 23 meters, they can get that 

too.” 

Meanwhile, further down the tunnel, 

the roar of the huge shuttering 

machine that is compacting the 

concrete for the inner shell makes 

conversation difficult. But when the 

machine is quiet for a moment, we’re 

able to ask construction foreman 

Georges Strickler about his 

experiences with the Colbond 

material. His reply is typically Swiss 

and typically down-to-earth: “Enkamat 

is easy to use. Most tunnels in 

Switzerland are built this way 

nowadays. That’s all. It’s a good 

product.” 

And what will the future bring for 

Giswil? The latest news is that the 

Swiss federal government has 

approved plans for yet another, 

slightly shorter, bypass tunnel to the 

north, between here and the town of 

Ewil. Construction will start in 2003, 

and the first cars will pass through in 

2006. Before long, the loudest noise 

in the valley of the Reuss may once 

again be that of cowbells. 


13

Polymer expertise and 

know-how: 

key ingredients for tailor-made 

product development for 

AlpTransit project 


Cross-section tunnel: 

rock 

gunite/shotcrete 

Enkamat/Enkadrain 

liner 

inner-wall 

lateral drains 

main drains 

“The largest challenge lies in cutting the time it 

takes to get technology out of our lab and into 

operations.” 

In the nineties the ambitious Swiss NEAT - Neue Eisenbahn 

Alpen Transversale (New Alpine Rail Axes) - infrastructural 

project was developed. The NEAT transalpine rail route 

system is designed as a network solution - in combination 

with the Lötschberg-Symplon and Gotthard axes - and will 

create new high-performance rail links on the north-south 

axes through Switzerland. 

The construction of the base tunnels, the 34 km long 

Lötschberg tunnel and the Gotthard tunnel with a length of 

some 57 km, is supervised by Switzerland’s AlpTransit 

authorities. The tunnels will be operational in 2012. 

(Also see our cover story pages 4 to 8). 

The base tunnels, for which a system consisting of two 

parallel single-track tunnels was selected, are being 

constructed according to the New Austrian Tunneling 

Method (NATM). This method, in which waterproof liners 

are part of the tunnel design, includes the protection of the 

inner side by shotcrete - either reinforced or not - and the 

installation of permanent steel supports such as anchors, 

lattice girders and full profile arches. After monitoring of the 

settlement, the drainage and protection layer and the 

waterproof liner are installed. Finally, the formwork is being 

placed, followed by pouring of the concrete for the inner 

concrete wall.

Waterproofing system 

The waterproofing system, consisting 

of the drainage and protection layer 

and the waterproof liner, plays an 

important role in the NATM tunnel 

design. 

The drainage and protection layer 

functions as: 

• drainage on the outside of the 

tunnel 

• cushioning layer between rock face 

and concrete structure 

• protection of the waterproof liner 

The waterproof liner offers protection 

against leakage. 

The waterproofing system must be 

continuous and easy to handle and 

install. 

As during installation and use, the 

waterproofing system is exposed to 

extreme mechanical, physical, 

chemical, and - incidentally - 

biological loads, the materials must 

be resistant to these loads. They 

must also be able to adapt to 

irregularities of surfaces on which 

they are installed and may not cause 

any harm to the environment. 

Challenging aspects 

The prestigious NEAT project 

includes a variety of striking and 

challenging aspects. 

The long base tunnels will provide a 

modern flat-trajectory line, allowing 

for substantially longer and heavier 

good and passenger trains that travel 

twice as fast. The latter trains can 

even reach a speed of some 200 

km/h. 

Such trains cannot be used on the 

existing Alpine lines, due to the steep 

grades and small radii of curvature. 

The flat-trajectory involves unusually 

deep construction - maximum 

overburden is 2,300 m - and high 

temperatures, which can reach 45ºC. 

The water pressure from strata 

overlying the Gotthard base tunnel 

has been estimated at as high as 100 

bar. 

High demands 

In view of the exceptional conditions, 

the materials to be used for the 

construction of the two base tunnels 

must meet the most stringent 

requirements for a designed service 

life of 100 years. 

Waterproofing systems, however, are 

relatively “young” and have only 

available for 30 years. This means 

that no long-term experience has 

been gained with these systems. 

Consequently, for this part of the 

tunnel construction the requirements 


15


regarding aspects such as 

temperature, overburden, and 

chemistry of the rock water have 

been tightened considerably. The 

material properties and behavior are 

to be tested and approved by the 

Swiss Federal Material Test and 

Research Institute EMPA. 

Test concept 

Separate tests are used to measure 

the performance of the drainage and 

protection layer and that of the 

waterproof liner. Tests are also made 

to determine the properties of the 

composite and the performance of 

the waterproofing system in the 

complete construction, including the 

concrete inner shell. 

The test concept includes: 

1. check of existing material tests 

according to SIA 280 or V 280 and 

the tests specified in the Swiss 

geotextiles handbook; 

2. laboratory tests to determine 

material properties and system 

technical suitability of the system; 

3. material, installation and technical 

laboratory tests as well as 

installation and handling tests and 

system behavior tests under onsite 

conditions. 

As NEAT was not quite sure about 

the conditions to be expected, the 

tests were made under extreme 

conditions. At an expected 

temperature of 40ºC, the requirement 

of 70ºC had to be met, while an 

expected pressure of 100 bar was 

translated into a requirement of 1,500 

bar.

The exceptional conditions of the 

project also affected the initial testing 

schedule, because the required 

materials simply did not exist. 

Despite their acknowledged excellent 

properties and performance in many 

tunnel applications, and positive test 

results, Colbond Geosynthetics’ 

Enkamat and Enkadrain materials did 

not meet all the extreme 

requirements. However, always 

focusing on better ways to do the job 

and to achieve improvement, 

Colbond Geosynthetics took up the 

challenge of dealing with uncommon 

requirements. 

Creativity put to productive use 

Colbond Geosynthetics put creativity 

to productive use in order to 

overcome the problems presented by 

the high pressure and the 

combination of heat and caustic 

composition of the rock. A major 

development program was initiated 

based on the comprehensive 

expertise and know-how available 

within Colbond Geosynthetics. 

Chemical analyses, extensive testing 

and trials were part of the intensive 

search to find the proper polymer and 

modification parameters. 

Polymers have their own chemical 

structure and feature different 

properties that make it impossible to 

simply replace one material by 

another without affecting the 

performance of the ultimate system. 

Upgrading one property could affect 

another characteristic. 

Colbond Geosynthetics has worked 

out several alternatives, which have 

been tested under a great pressure of 

time. Hardly had the technology left 

the lab, when it was already 

converted into the material for the 

waterproofing system. 

All the efforts have resulted in a 

drainage product based on a core 

and filter made of polypropylene. In 

combination with a waterproof liner 

produced by the Swiss company 

Sika, a reliable waterproofing system 

that exceeds the standards and 

meets the exceptional requirements 

has been provided. 

Having passed the test, the system 

has been approved for use in the 

prestigious AlpTransit tunnel project. 

Some 80,000 m 2 have already been 

installed in lateral tunnels and portals. 


17

Enkamat ® & Enkadrain ® : 

High-performance flexibility 


In tunnel-building, Enkamat and Enkadrain serve a 

number of specific functions. In addition to 

protecting the waterproof liner and allowing an outlet 

for runoff and seepage, as seen at the Giswil tunnel 

and others using the NATM technique, these 

products are also used in open-cut tunnels to 

provide drainage on the outside. In special cases, 

they can even serve as a grip-layer for the shotcrete 

lining. 

The insensitivity to clogging of these geosynthetics, their 

easy installation, proven high performance and low 

inflammability make Enkamat and Enkadrain the drainage 

materials of choice for mined and bored tunnels, open-cut 

techniques, tunnel repair and special projects (such as the 

use of injection and expansion layers and the fabrication of 

micro-tunnels for power stations). 

In tunnels that are blasted or bored using a Tunnel Boring 

Machine (TBM), the installation of geosynthetic drainage 

mats and waterproof lining commonly begins after a period 

(6 months to a year) of monitoring rock settlement. 

The shotcrete sprayed first is very rough material indeed, 

with surface irregularities of up to 10 mm. After the 

shotcrete has dried, seepage and leaks may become 

visible. These spots require drainage, but can in the course 

of time wander and reappear at other places in the tunnel 

wall. Local drainage is therefore not enough: lining the 

entire tunnel wall with drainage material is the choice of 

most specifiers. 

Enkamat is attached to the shotcrete wall with shoot nails, 

fitted with PVC disks. And because of its flexibility and 

structure, Enkamat adheres well to even the most irregular 

shotcrete wall. 

The waterproof liner is attached starting at the roof of the 

tunnel, and working down. For this purpose, a special 

hydraulic rolling scaffolding is used. Once the sheets of liner 

are in place, they can be double-welded along the seams, 

and to the drainage system at the bottom of the tunnel wall, 

and tested for impermeability by means of compressed air.

Once the drainage layer and liner are in place and tested 

for leakage, the concrete inner wall of the tunnel is applied 

directly over the liner. For this purpose, a special shuttering 

machine is used. 

For open-cut tunnels, obviously, a very different technique is 

applied. Here the separate, pre-fabricated segments of the 

tunnel are put in place and sealed against leakage with 

bitumen strips. Enkadrain TP, for example, is then applied to 

protect the seals and provide drainage. A major advantage 

of Enkadrain TP in this respect is that it works when 

installed either vertically or horizontally, and can therefore 

protect open-cut tunnel roofs as well. 

Both Enkamat and Enkadrain provide excellent permeability 

and transmissivity, and can protect the waterproof liner 

against puncturing. A good reason for many of the world’s 

most demanding tunnel-builders to specify these 

geo-spacers. 


19

Underslating/drainage composite 

layers in metal roofings 


Already in the mid-nineties Rheinzink and Colbond Geosynthetics 

commercialized the first underslating/drainage composite layer. 

After initial teething problems these novel composite layers made 

headway, especially for use in slightly inclined roofs. Thanks to 

numerous advantages over conventional underslatings, the utilization 

of these products turned from being the exception to becoming the 

rule. Nowadays the insertion of underslating/drainage composite 

interlayers is not only recommended by all leading zinc 

manufacturers and represents the state of the art; it is even 

prescribed in directives. In paragraph 3.2.3 of DIN 18339, regarding 

titanium-zinc roofs of up to 15° roof pitch, the express requirement is 

made for insertion of a composite layer having a drainage function, 

i.e. an underslating/drainage composite one. In the new concepts of 

construction recommendations for the roofers as well as plumbers’ 

professional associations, the use of these new composite layers is 

prescribed too. 

New construction-acoustical insight 

and practical experience show 

moreover that not only with titaniumzinc 

covers but with any kind of metal 

cover it makes technical sense to 

apply an underslating/drainage 

composite layer. Besides their 

function as a covering in the 

construction stage these products 

show essential advantages over 

conventional underslatings. They 

create a space between the 

substructure and the metal cover, 

thus providing a drainage layer. 

This technically required drainage 

layer allows to securely drain off any 

undesired moisture having seeped in 

due to the constructional layout, 

through minor leaks or from ice 

flakes. Any occluded moisture can 

diffuse out of the roof structure 

without difficulty. Slight irregularities 

in the substructure (formwork 

tolerances, nail imprints etc.) are 

compensated and will not show 

through at the metal surface. A further 

consideration in favor of applying an 

underslating/drainage composite 

layer should be the improvement of 

the “gliding capacity”, especially with 

long metal sheets.

Present state of development in 

structured interlayers 

Basically two groups of 

underslating/drainage products can 

be distinguished. On the one hand 

there are the three-dimensional, 

structured polymer mats such as 

Enkamat 7008 of Colbond which are 

usually laid out on a separately 

installed underslating of glass-mat 

bitumen (V13) or on some other 

bedding. Occasionally such 

underslating is left away. 

On the other hand there are the 


layers. These are laminated products 

in which a three-dimensionally 

structured polymer mat is directly 

bonded to a vapour-open 

underslating. 

This underslating is as a rule a 

waterproof vapour-open membrane, 

protected on both sides against 

mechanical damage by a nonwoven. 

Until recently, underslating/drainage 

composite layers, which were not 

vapour-open, were also available, but 

by now, these have virtually 

disappeared from the market. 

All presently available 


layers are 6 - 8 mm thick. They are 

applied in an identical manner to any 

conventional underslating. No special 

tools for their installation are required, 

nor are special fastenings to the 

overlying metal sheets. 

The differences among the products 

on offer are in the choice of geometry 

of the three-dimensional structure 

(random, ribs, cusps), the polymer 

employed (polyester, polyamide) and 

the mode of bonding between the 

structured mat and the underslating 

(bituminous or thermal). In choosing 

the right underslating/drainage 

composite layer special attention 

should be paid to the ease of 

installation and the flatness of the 

mat. Selection of a too rigid 

structured mat can result in waviness 

of the support. 

The butt joints are executed as with 

conventional underslatings: the strips 

of the product are given 

approximately 10 cm overlaps and 

are bonded. 


21


When does the use of an 

underslating/drainage 

composite layer serve the 

purpose? 

In ventilated roof designs the 

necessity of an underslating/drainage 

composite layer depends on several 

factors. In slightly inclined roofs 

(3° - 15°) an underslating/drainage 

composite layer must be installed in 

any event. Also, when wood or woodbased 

materials or large-sized roof 

elements are employed, then 

independently of the roof pitch the 


layer should definitely not be omitted. 

With steep roofs (> 15°) where 

temporary moisture protection is 

needed (i.e. in the construction 

stage), its use makes sense too. In 

case a separate underslating is 

already in place, a bare structure mat 

(e.g. Enkamat 7008) should be used.

In the case of non-ventilated metal 

roofs, whatever the roof pitch and 

substructure, the rule should be to 

install an underslating/drainage 

composite layer between the thermal 

insulation and the metal cover. The 

thus ensured ventilation leads off 

moisture and - due to this effect - 

lengthens the life span of the 

insulation and the metal cover. 

Noise reduction by up to 50% 

Metal roofs are found on all types of 

buildings, mostly on buildings having 

slightly inclined roofs and high-grade 

residential dwellings. In these cases 

in particular, much value is placed on 

the high quality of dwelling and living. 

A substantial factor of influence here 

is the level of noise entering the 

premises. Of particular importance is 

the reduction of pounding noises 

generated on metal roofs in extended 

roof framings, since the living room 

directly adjoins the roof. Thus, 


layers contribute in more than one 

way to the quality of metal roofings. 

Recent tests executed by the WTCB 

institute have shown that the 

application of underslating/drainage 

composite layers considerably 

reduces the intensity of pounding 

noises. In particular the propagation 

of low frequencies can be reduced 

much. 

Depending on their structure and 

material the various structured 

interlayers achieve slightly varying 

degrees of noise reduction. By 

installation of a Bauder Top Vent 

02NSK, a Dörken DELTA TRELA or 

an Enkamat 7008 in combination with 

a glass-mat/ bitumen underslating, 

the noise level can be reduced by up 

to 50%. As far as construction 

acoustics are concerned, inserting 

solely a glass-mat/ bitumen 

underslating (V13) offers hardly any 

advantage. An only 1 dB reduction 

was measured, a difference not 

perceptible to the human ear. 


23

Short News ✰ Short News ✰ Short News 

CE marking for 

Colbond Geosynthetics products 

According to the rules and regulations within the European Union, Colbond 

Geosynthetics’ products will be CE marked as from October 1 st 2002. 

CE marking is intended to facilitate the free movement of products within the 

EU by signifying that essential health and safety requirements have been 

met. 

The CE marking comprises the CE symbol together with other information as 

may be required by the European Union directives applying to a particular 

product, printed on the product label. The marking is a legal requirement for 

products covered by one or more of the EU directives stipulating its use. 

Relevant product characteristics with 

variances will be printed on an 

accompanying document. 


The quality assurance process for the 

CE marking is supervised by a Notifying 

Body, which has entered into an 

agreement with Colbond Geosynthetics 

to do so. 

New Development and Application Center 

Colbond Geosynthetics’ Product Development and Testing Department recently 

moved into Colbond’s new state-of-the-art Development and Application 

Center, located at the company’s facility in Arnhem, the Netherlands. 

The new center is designed and equipped for product development, application 

research and the evaluation of products for specific applications, and 

concentrates all activities of the business unit in this field. 

Most of the Geosynthetics’ test equipment in the center has been developed 

in-house by the department’s team of specialists and complies with 

internationally accepted standards such as ISO, ASTM and CEN. 

Long-term drain testing, automated tensile testing, creep testing, and heavy 

duty tensile testing are among the tests being carried out here. 

The new center provides an additional platform for exchanging knowledge and 

ideas with our partners in the market. 

New sales office 

in Argentina 

In the context of its endeavors to 

increase efficiency for all sales 

activities in the South American 

region, Colbond Geosynthetics 

opened a new sales office in Buenos 

Aires, Argentina, at the beginning of 

this year. 

The office is run by Latin America 

Sales Manager Aline Rebaudo. 

Address: 

Colbond Geosynthetics 

c/o Organon S.A.Q.I. y C. 

Mcal A.J. de Sucre 865 

1428 - Buenos Aires 

Argentina 

Tel.: +54 11 4789 7500 

Fax: +54 11 4789 7550 

Email: aline.rebaudo@ar.colbond.biz

Reinforced Enkamat 

Filled Armater 

Enkagrid ® PRO 

picked for Floriade 

Added soil layer 

Subsoil 

Enkadrain 

In April 2002 the fifth Floriade - the world largest 

horticultural exhibition in the Netherlands, held once every 

ten years - opened its gates, expecting to welcome some 

three million visitors from all over the world. 

Big Spotters’ Hill - with a large watchtower constructed on 

top - represents a spectacular highlight of the exhibition with 

its height of more than 40 m and overlooking the impressive 

exhibition area. 

Big Spotters’ Hill was built from 500,000 m 3 of sand 

(= 40,000 truckloads) in layers of five meters depth. At the 

base it covers an area measuring 230 x 230 meters, the 

same dimensions as those of the Pyramid on Cheops in 

Egypt. 

The final layer of the construction has steep angled at more 

than 45º. Anticipating a large number of visitors on the hill, 

the engineers - using the EnkaSlope software program - 

selected Enkagrid PRO 40 to reinforce the structure for 

additional safety. 

On another level an innovative solution designed by 

Colbond Geosynthetics provides Big Spotters’ Hill with 

drainage by Enkadrain, stabilization by reinforced Enkamat 

and erosion control by Armater. 

(For more information on Floriade: www.floriade.nl) 


25

Their successful solo performances 

apart Enkagrid PRO and Enkamat 

can also join forces in an interesting 

‘partnership’, using the potential and 

flexibility of the two products. 


Enkagrid ® PRO and Enkamat ® 

a fruitful combination 

The local Department of 

Transportation in the mountainous 

area of the French Pyrenees decided 

to widen the existing access road to a 

tourist site while preserving the 

beautiful green scenery. So, instead 

of cutting the road into the mountain, 

soil reinforcement was used to build 

upwards from the valley-side. 

For this purpose a steep slope 

reinforced with Enkagrid PRO 

geogrids was designed. In order to 

improve the establishment of natural 

vegetation Enkamat 7010 was placed 

behind the geogrid, thus ‘closing’ the 

square geogrid structure. 

After construction hydro-seeding with 

seeds, compost, and mulch was used 

to successfully cover the steep slope. 

Natural slope 

Road 

Enkagrid PRO layers 

Compacted gravel 

Enkamat filled 

by hydro-seeding

Mekastone and Enkagrid 

support 

World Cup Soccer 2002 

The 17 th World Cup (June 2002) is 

the first World Cup finals to be shared 

by two hosts, Korea and Japan, and 

the first finals organized in Asia. 

The modern stadium in Jeon Ju, 

some 232 kilometers south of Seoul, 

was completed in the fall of 2001 and 

is one of the 10 Korean stadiums 

specially built for this event. The 

access road to the 42,477-seat 

stadium is made up of a 14-meter 

high retaining wall on soft soil, 

constructed by Mekamore. 

Mekamore, Colbond Geosynthetics 

partner for Enkagrid in South Korea, 

used their innovative, very flexible 

and easy to install block wall system 

which combines Mekastone and 

Enkagrid. The general concept of the 

system includes the use of 

Mekastone concrete units, 

Enkagrid PRO and Mekapin, a 

special pin enabling construction with 

different wall batter. 

The system permits incorporation of 

standard and half units, easy 

installation of serpentine walls with 

minimized curvature, and optimum 

utilization of the Enkagrid PRO 

advantages such as powerful and 

durable soil reinforcement and ideal 

interaction with all soil types. 


27

Worldwide network 

Country Firm, place Phone Fax 

Andorra Sapec, Andorra la Vella (+376) 825123 (+376) 862593 

Argentina Maccaferri de Argentina, Buenos Aires (+54) 3327 457522 (+54) 3327 455394 

Australia Maccaferri Pty Ltd., Seven Hills (+61) 2 88256300 (+61) 2 88256399 

Austria Leopold Wintoniak Industrievertretungen, Vienna (+43) 1 3697373 (+43) 1 3697303 

Belgium Tecmat N.V., Alleur (+32) 4 2390700 (+32) 4 2474626 

Montauban N.V., Nieuwkerken-Waas (+32) 3 7779695 (+32) 3 7779743 

Bolivia Maccaferri Gaviones de Bolivia, La Paz (+591) 407992 (+591) 407992 

Brunei Chrisphilip Sdn. Bhd., Bandar Seri Begawan (+673) 2 652561 (+673) 2 652563 

Brazil Maccaferri do Brasil Ltda., Saõ Paulo (+55) 11 4589 3200 (+55) 11 4582 3272 

Canada Ten Cate Nicolon, Pendergrass, Georgia, USA (+1) 706 6932226 (+1) 706 6934400 

Caribbean Ten Cate Nicolon, Pendergrass, Georgia, USA (+1) 706 6932226 (+1) 706 6934400 

Central America Maccaferri de Centro America Ltda. (+506) 2895564 (+506) 2895464 

(San José, Costa Rica) 

Chile BANFF, Santiago de Chile (+56) 2 204 9444 (+56) 2 204 03503 

China Akzo Nobel China bv, Shanghai (+86) 21 6354 88 48 (+86) 21 6354 8845 

Colombia Maccaferri de Colombia, Santa Fé de Bogotá (+57) 1 613 5021 (+57) 1 613 5021 

Cyprus Tsircon Co. Ltd., Nicosia (+357) 2 487029 (+357) 2 487716 

Denmark Byggros A/S, Holbæk (+45) 5948 9000 (+45) 5948 9005 

Dominican Republic HACHE/ Maccaferri, Santo Domingo (+1) 809 5661111 (+1) 809 5664589 

Egypt Geos, Cairo (+20) 2 243 52 63 (+20) 2 2918236 

Equador Maccaferri de Equador, Quito (+593) 292 4069 (+593) 292 4069 

Finland Kaitos Oy, Helsinki (+358) 9 3507060 (+358) 9 35070610 

France Colbond Geosynthetics SarL, Saint Denis la Plaine (+33) 1 49462430 (+33) 1 49462435 

French Guyana Ets Serge Ampigny, Lamentin (+596) 504949 (+596) 500195 

Germany Colbond Geosynthetics GmbH, Obernburg (+49) 6022 812 020 (+49) 6022 812 800 

Greece Polykem SA, Agios Stefanos Attica (+30) 1 8161857 (+30) 1 8161131 

Hong Kong Spray Engineering Corp., Hong Kong (+852) 25757871 (+852) 28382615 

India Z-Tech (India) Pte. Ltd., New Delhi (+91) 11 6227271 (+91) 11 6227273 

Indian Ocean Islands Omniplast, Sainte-Marie, Réunion (+262) 534131 (+262) 531524 

Indonesia P.T. Tetrasa Geosinindo, Jakarta (+62) 21 633 0150 (+62) 21 633 6706 

Iran Iran Bana Arian Co., Teheran (+98) 21 877 9440 (+98) 21 8771457 

Ireland Lining Services Ltd. Waterford (+353) 51879944 (353) 51855416 

Israel Admir Technologies Ltd., Tel Aviv (+972) 3 9604016 (+972) 3 9604713 

Italy Harpo Seic, Trieste (+39) 0403186611 (+39) 0403186666 

Japan Tokyo Zairyo Co., Ltd., Tokyo (+81) 3 5472 1508 (+81) 3 5472 1606 

Kuwait Al Bahar & Bardawill Specialties Co. W.L.L., Safat (+965) 481 2144 (+965) 483 6193 

Luxemburg Montauban N.V. (Nieuwkerken-Waas/Belgium) (+32) 3 7779695 (+32) 3 7779743 

Polyma S.A., Mondercange (+352) 26 55 3535 (+352) 26 55 3500 

Malaysia Maccaferri Malaysia Sdn. Bhd., Selangor (+60) 3 7955 7800 (+60) 3 7955 7801 

Martinique Ets Serge Ampigny, Lamentin (+596) 504949 (+596) 500195 

Mexico Ten Cate Nicolon, Pendergrass, Georgia, USA (+1) 706 6932226 (+1) 706 6934400 

The Netherlands Colbond Geosynthetics, Arnhem (+31) 26 3664600 (+31) 26 3665812 

Nepal Maccaferri PVT. LTD., Kathmandu (+977) 1 414271 (+977) 1 420049 

New Zealand Maccaferri NZ Ltd., Auckland (+64) 9 6346495 (+64) 9 6346492 

Norway Geonor A/S, Oslo (+47) 67159280 (+47) 67145846 

Oman Suhail & Saud Bahwan, Muscat (+968) 771 0983 (+968) 771 5755 

Peru Maccaferri Peru S.A.C., Lima (+511) 4300292 (+511) 4300289 

Philippines Maccaferri Philippines, Quezon City (+63) 2 749 2438 (+63) 2 749 2438 

Poland GTT, Kielce (+48) 601801443 (+48 ) 413315639 

Portugal Arco Portuguesa, Lisboa (+351) 21 8823700 (+351) 21 8823709 

Qatar Al Obeidly & Gulf Eternit, Doha (+974) 325111 (+974) 367217 

Russia Geotechkomplex, Moscow (+7) 095 746 00 13 (+7) 095 180 55 71 

Saudi Arabia Trading & Development Partnership, Riyadh (+966) 1 4194444 (+966) 1 4193058 

Singapore Colbond Geosynthetics, Singapore (+65) 6 258 1333 (+65) 6 259 8607 

Geocom, Singapore (+65) 741 6308 (+65) 745 8972 

South Africa Kaytech Geotechnical & Industrial Fabrics, Pinetown (+27) 31 7010352 (+27) 31 702 44 77 

South America Colbond Geosynthetics, Buenos Aires (+54) 11 4789 7500 (+54) 11 4789 7550 

South Korea Korea C & S Co. Ltd., Seoul (+82) 2 2217 8740 (+82) 2 2217 8730 

Mekamore Co. Ltd., Seoul (+82) 2 552 5546 (+82) 2 552 5543 

Yuyang Construction & Industry Co. Ltd, Seoul (+82) 2 589 3571 (+82) 2 589 3579 

Spain Terratest Tecnicas Especiales, S.A. Madrid (+34) 91 423 7562 (+34) 91 423 7501 

Sweden bg Byggros ab, Malmö (+46) 40 43 66 30 (+46) 40 43 66 36 

AB Periskopet, Stockholm (+46) 8 673 55 22 (+46) 8 673 2040 

Switzerland Schoellkopf AG, Zürich (+41) 1 3121616 (+41) 1 3121626 

Bossard & Staerkle AG, Zug (+41) 41 7691240 (+41) 41 7614569 

Taiwan Jess Enterprise Co. Ltd., Taipei (+886) 2 25042243 (+886) 2 25050407 

Newmark Engineering Products Co Ltd, Taichung (+886) 4 355 0357 (+886) 4 355 0359 

Thailand Maccaferri Thailand Ltd. (+66) 2 717 0209 (+66) 2 717 0208 

Turkey Imtek Ltd. STI, Istanbul (+90) 216 3863274 (+90) 216 3586737 

United Kingdom Maccaferri Ltd., Oxford (+44) 1865 770 555 (+44) 1865 774 550 

U.A.E. Mirjana Engineering Supplies, Abu Dhabi (+971) 2725985 (+971) 274 8065 

Al Bayan Technical Equipment Est., Dubai (+971) 4 268 9524 (+971) 4 268 9568 

U.S.A. Colbond Geosynthetics Co., Enka, N.C. (+1) 828 6655010 (+1) 828 6655009 

Ten Cate Nicolon, Pendergrass, Georgia (+1) 706 6932226 (+1) 706 69344 

Venezuela Maccaferri de Venezuela, Caracas (+58) 212 241 3289 (+58) 212 242 4495 

Vietnam Maccaferri Asia (+60) 3 7957 8330 (+60) 3 7957 9080

Volume 7, no. 13 - Colbond Geosynthetics

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