edition august 2008 - basf · the name elastocoast. successfully realized reference projects...

Edition August 2008

1

1 Abstract______________________________________________________________________ 2

1.1 Polyurethanes (PU) ______________________________________________________ 3

2 The innovation Elastocoast_______________________________________________________ 4

2.1 Conventional revetments _________________________________________________ 4

2.2 Elastocoast : The idea_____________________________________________________ 5

2.3 Processing and installation ________________________________________________ 5

2.4 Performance of hydraulic constructions_____________________________________ 6

2.4.1 Hydraulic function ________________________________________________ 6

2.4.2 Dimensioning _____________________________________________________ 8

2.4.3 Overtopping dikes_________________________________________________ 8

2.4.4 Monitoring _______________________________________________________ 9

Laserscanning_____________________________________________________ 9

Wave and wind observation _______________________________________ 10

2.5 Weather resistance ______________________________________________________ 12

2.6 Environmental compatibility _____________________________________________ 13

2.6.1. Effect on aquatic ecological systems _________________________________ 13

2.6.2. Recolonization of flora & fauna on Elastocoast revetments _____________ 13

Project Zuidbout _________________________________________________ 13

Project Petten ____________________________________________________ 14

Laboratory Experiments ___________________________________________ 14

Summary________________________________________________________ 15

2.7 End of lifetime and disposal ______________________________________________ 16

2.8 Eco-efficiency __________________________________________________________ 16

2.9 Cost effectiveness _______________________________________________________ 18

3 Reference projects ____________________________________________________________ 19

4 Further non-coastal applications__________________________________________________ 34

Addendum______________________________________________________________________ 38

Documents_____________________________________________________________ 38

Newspaper articles______________________________________________________ 38

Publications in appendum _______________________________________________ 39

Publications not in appendum ____________________________________________ 39

E l a s t o c o a s t A n i n n o v a t i v e T e c h n o l o g y i n C o a s t a l P r o t e c t i o n . . . t o d a y a n d t o m o r r o w

2

1Revetments with Elastocoast are a new and innovative coastal protection system. The term Elastocoast means a

bonding system that reinforces hydraulic gravel at their contact surfaces permanently by means of the 2-

component plastic polyurethane (PU).

In a common research project of Elastogran

GmbH, a BASF subsidiary, and the TU

Hamburg-Harburg (TUHH) the suitability of

the use in coastal protection systems has been

proven and the long-lasting stability under

environmental influence has been

demonstrated. In a further research

cooperation with TU Delft and the engineering

office ARCADIS (NL), additional tests and

dimensioning procedures (GOLFKLAP) for the

use of Elastocoast in accordance with

international standards has been provided.

The material PU which is environmentally compatible sticks the hydraulic gravel together, resulting in a

monolithic, three-dimensional and stable structure. The small amount of PU used ensures that the structure

remains completely porous and the wave impact is far better absorbed. The result: a reduced wave run-up and

therefore a decreased potential of damage.

Furthermore, this new technology is more cost effective as a substantial amount of construction material is saved

due to the high resistibility of the PU.

Elastocoast consists of approx. 50% of renewable raw materials and was nominated for the BIOPLASTICS Award

2007 of the European Plastics News (see addendum). This innovation is now well known by experts under

the name Elastocoast. Successfully realized reference projects performed on a total area of approx. 15,000 m 2

shows that revetments reinforced with Elastocoast provide a fully approved alternative in the field of coastal

protection constructions, and that Elastocoast is on the right track to become an established technology.

This report is supposed to serve the operators (architects, planners, engineers and executing construction

companies) as a source of information and guideline. Besides the principle of the installation procedures,

hydraulic features and environmental compatibility, the reference projects performed at the coasts in northern

Germany, the Netherlands, France and the UK will be presented.


3

1.1 POLYURETHANES (PU)

Polyurethanes (PU) the material of opportunities basically consists of two types of raw material, namely

isocyanate and poylol. Mixing the two components together, results in a reactive mixture. Depending on the

formulation and mixing ratio, the range of properties of the finished PU may be controlled exactly to produce

rigid, flexible, integral, cellular (foamed) or compact products.

The fields of application are as diverse as the people for which they are created.

Elastogran offers a wide range of PU for applications in the automotive, furniture, sports & leisure, electronics,

medical technology and construction industries.


4

2The developments of new revetment systems are subject to various requirements. These requirements refer to the

resistance against hydraulic impact but also to various interactions in the natural environment. In addition to the

permanent attack of weathering, aspects of neutrality with regard to ecological toxicity or visual integration into

the landscape are also very important.

The permanent stability of a revetment ensures the protective function of the structure. Particularly damage

created by stones that brake away from the composite construction are of risk for the security of the whole

structure.

2.1 CONVENTIONAL REVETMENTS

Revetments are constructions that serve as a protection against erosion of the coastal and shore subsoil. There are

two types of revetments, loose and reinforced revetments.

Loose revetments are maintained in their position only by their own weight or their toothing and are usually not

suitable for a severe coastal protection, i.e. against heavy hydraulic loads.

In the case of reinforced revetments, the stones are reinforced to a monolithic structure by the input of bonding

agents.


5

The Open Stone Asphalt and the bitumen grouting have to be processed at up to approx. 200 C. The surfaces

are extensively sealed by the concrete or bitumen grouting (Fig. 2.1.3 and 2.1.5). The permeability of the

revetment is not ensured in this case.

In case of Open Stone Asphalt (O.S.A.) (Fig. 2.1.4), a partial permeability is maintained but the free volume of

pores is drastically reduced due to the high content of bitumen of 20 to 30%. Furthermore, the use of revetments

with Open Stone Asphalt as a severe coastal protection is only possible to a limited extent as it has a limited

erosion resistance.

In case of a sealed surface, the revetment is fully loaded by the wave pressure impact without restrictions. As a

result of this, abrasions, erosions and damage may occur. The wave energy cannot be absorbed and runs ashore.

Therefore, a construction with a high porosity is preferred but the high ratio of bonding agents always results in

complete or partial loss of porosity. However, this high ratio is necessary and essential in order to construct

bitumen and concrete revetments in a way that ensures resistance from erosion as far as possible.

2.2 ELASTOCOAST : THE IDEA

The fact is: only a material with high strength and elasticity may be considered.. First, in order to maintain the

porosity by means of a low content of bonding agent and second, in order to reach a high erosion resistance.

Furthermore, the material has to be practical concerning installation under difficult construction site condition

onshore and environmentally compatible.

In cooperation with the TUHH (institute for hydraulic engineering) this complex challenge was overcome. The

result is not only a new PU-material but also a completely new concept for the construction of revetments for

coastal protection called Elastocoast. Elastocoast features easy processing and a high ratio of free pores. It may

readily be integrated into the landscape and has a high environmental compatibility.

In the course of a system analysis, all crucial features of the new material and of the Elastocoast revetments were

researched experimentally and translated into physical law. Within this cooperation, BASF / Elastogran was

responsible for the development of the physical and chemical features also with regard to processing, mechanics,

stability and environmental compatibility. The TUHH examined aspects of hydraulic engineering with regard to

hydraulics, realization of pilot projects and its analysis by laser surface scans after storm surges.

2.3 PROCESSING AND INSTALLATION

The developed processing technique is practical, very easy and is performed on the spot (see Fig. 2.3.1-2.3.3).

Gravel with a small grain size is mixed in a conventional cement mixer with only approx. 3 vol. % of the cold

curing 2-component PU bonding agent. This process takes only approx. 5 minutes. The PU cures and is reaches

its final strength after one day.


6

The stones used have to be clean and surface-dry before being processed (see addendum; 10-points-processing-

guideline). This is a requirement that seems to be difficult at first sight. As other realized projects show, certain

simple measures regarding handling and logistics eliminate this obstacle.

The material consists of approx. 50% of vegetable fatty acid esters, thus renewable raw materials. In addition,

due to the high porosity cavities provide additional habitat for animals and plants. Also the Elastocoast

revetments easily integrate into the overall appearance of the landscape. Due to the transparency of the material,

it is difficult to set them apart from naturally painted rip-rap (see Fig. 2.3.4 and 2.3.5).

Before the material has completely cured, the surface can be covered with dry sand by which the visual effect is

additionally adjusted and a skid resistant surface can be created.

2.4 PERFORMANCE OF HYDRAULIC CONSTRUCTIONS

2.4.1 HYDRAULIC FUNCTION

As stated above, a porous structure revetment offers measurable advantages. If water masses run on a sealed

surface, they will turn into a wave without being slowed down and eventually brake with their full destroying

power and be reflected. (see Fig. 2.4.1.1)


7

However, if water masses run on a porous surface, part of the hydraulic energy will be absorbed by friction in

the volume of pores and eventually transformed into thermal energy. The water masses will reach a lower wave

runup with lower hydraulic energy and reduced damage potential as a result of this (see Fig. 2.4.1.2).

This reduced wave run-up was clearly proven in a wave channel test that was performed at an Elastocoast

revetment (see Fig. 2.4.1.3). The lower portion of binder agent, and the use of larger sized stones, results in a

more open structure and lower wave run-up.

1,5

2,0

2,5

3,0

3,5

1,0 1,5 2,0 2,5 3,0 3,5 4,0

Rel

ativ

ew

ave

run

up

[Ru

/

sealed concrete surface

Elastocoast revetment (Stonesize 8 - 11 mm)

Elastocoast revetment (Stonesize 16 - 32 mm)

However, the high porosity has a further advantage. Levee bodies are waterlogged in the case of high tide and

are subject to overpressure. When the water level decreases, this overpressure may lead to a destabilization.

Hence, the overpressure has to be relaxed and this is reached faster and safer by means of porous revetments.


8

Abrasion tests show that Elastocoast is much more resistant to erosion and abrasion than Open Stone Asphalt.

The TU Delft was able to achieve these results by using the equipment shown in Fig. 2.4.1.4 and 2.4.1.5 in which

test specimen were exposed to an erosion load consisting of coarse gravel and water in a barrel.

2.4.2 DIMENSIONING

Mechanical studies and correlations of the TUHH showed that the marginal load of 8 m wave height and a flow

velocity of 10 m/s may be reached. This proves that PU-revetments as compared with conventionally reinforced

revetments have at least the same stability features and therefore meet the necessary requirements.

Layers of Open Stone Asphalt can be calculated by the mathematic GOLFKLAP-simulation (NL; TU Delft) based

on expected wave height and corresponding wave pressure impacting the revetment. Based on the frequency-

dependent mechanical data of Elastocoast analyzed by TU-Delft, it was possible to transfer the GOLFKLAP-

simulation to Elastocoast revetments. Therewith a method of calculation was made available that constitutes an

essential element for a safe evaluation and dimensioning of the construction of PU revetments whilst taking into

account the expected hydraulic load.

Calculations have shown that based on equal expected hydraulic impact thicknesses of Elastocoast revetment

layers may be reduced by up to 50%, which results in substantial savings regarding construction costs.

This method was applied to the potential project Sylt Hindenburgdamm (Morsum Keitum) by TU Delft.

Hereby the Elastocoast revetment with a thickness of 15 cm is shown to be able to resist a significant wave height

of 5.2 m in comparison with a maximum wave height of 2.0 m in case of an Open Stone Asphalt revetment (see

addendum).

2.4.3 OVERTOPPING DIKES

Experts are forecasting a sea level rise up to 50 cm until the year 2100 caused by global warming. However no

report is able to predict when, where and what might be the effective sea level and wave impact by that time.

Consequently all coastal and flood protection measures, especially dikes must be upgraded by increasing their

height. The feasibility of this is most unlikely due to the high financial investments required as well as technical

reasons due to lack of space for increasing the dike levels. Consequently this will also result in broadening the

dike base.


9

Overtopping a dike by water masses with high flow speeds is one of the most dangerous scenarios as this can

cause landside erosion and a total failure of the dike. At the moment hydraulic engineers are discussing how to

protect dike surfaces on the land side from erosion by overtopping.

Early April 2008 Rijkswaterstaat executed a test with an overtopping simulator on an Elastocoast revetment as

well as on other constructions like grass and Open Stone Asphalt (O.S.A.). In three series of tests the simulator

released 30, 75 and 125 liters per meter per second impacting the Elastocoast revetment over six hours each (see

Fig. 2.4.3.1. and 2.4.3.2.)

Even at the highest flow rates ever tested of 125 l/m*s no single damage was monitored and the Elastocoast

revetment was analyzed as the most stable construction.

2.4.4 MONITORING

LASERSCANNING

In order to provide the proof of steadiness and erosion resistance of Elastocoast revetments, laser surface scans

were applied to the pilot project Hamburger Hallig (approx. 120 m 2; built in October 2004) by TUHH in October

2005 and March 2007 (see subsequent Figures). The marked results were analyzed comparatively.


10

The difference between the two scans (Fig. 2.4.4.2) is shown in 2.4.4.3 analyzes possible changes of the revetment

concerning lift, subsidence or other superficial erosions for the respective time period that would be marked

green or red. However, Fig. 2.4.4.3 illustrates that no substantial changes have occurred hence the steadiness of

this Elastocoast revetment is validated.

WAVE AND WIND OBSERVATION

Two pilot sites were installed in 2007 in the Netherlands at Oosterschelde-Zuidbout and Petten with layers of 10,

20 and 30 cm each.

During the storm season 2007/2008 a detailed monitoring analysis was executed by TU Delft in cooperation with

the engineering office ARCADIS (Elastocoast Pilots in the Netherlands Storm Season 2007/2008 Bijlsam, E.;

TU Delft 2008 ).

Detailed data provided by wind and wave observations in the Oosterschelde are the base of the correlation with

the stability of the Elastocoast revetments.


11

The Figure 2.4.4.5 shows wind speeds in m/s and also Beaufort scale. In the season, running from October 2007

to April 2008, six storm periods were observed with wind speeds peaking above 17 m/s.

During this period the Elastocoast revetment was checked for possible damages. Figure 2.4.4.6 shows a

quantitative monitoring of the stability during the current season providing number of eroded stones versus time

of observation

Following conclusions can be draw:

o Microscopic damages of the Zuidbout and Petten Elastocoast revetments are negligible.

o There are only superficial abrasions.

o Even the 10 cm layers performed as stable construction

0.00%

0.10%

0.20%

0.30%

0.40%

0.50%

0.60%

0 50 100 150 200

Numberofdaysafterconstruction

Damagepercentage

Zuidbout

average

Petten

average

0.00%

0.10%

0.20%

0.30%

0.40%

0.50%

0.60%

0 50 100 150 200

Numberofdaysafterconstruction

Damagepercentage

Zuidbout

average

Petten

average


12

2.5 WEATHER RESISTANCE

Hydraulic engineering structures are expected to have a life time of 20 years and more. All construction materials

on inorganic (cement-bonded) or organic (plastics) basis are subject to the impact of weathering when used

outdoor. Particularly damage caused by ultraviolet radiation, salt water and frost must be considered. PU

materials are established in outdoor applications such as concrete and sports ground coating or offshore, oil and

gas pipelines resisting salt water attack.

The resistance of Elastocoast against salt water was validated by using the so-called Arrhenius-correlation (EN

ISO 2578; see Fig. 2.5.1). In doing so, the degradation process that takes place in sea water very slowly at low

temperatures was accelerated by increasing temperatures of up to 80C in order to extrapolate the results at 20-

30C afterwards. This extrapolation shows, that the PU-material is fully stable in salt or sea water at service

temperature of 20 30 C.

0,1

1,0

10,0

100,0

1000,0

0 10 20 30 40 50 60 70 80 90

Lif

etim

e in

exp

ecta

tion

1,9

0,7

0,2

extrapolate

measured

Lifetime in expectation

at 20-30 C

The TUHH provided evidence that there is a sufficient persistence when exposed to UV irradiation, tested in

special developed water transition area equipment. The frost resistance is secured by tests in accordance with

DIN EN 13383-2 (see appendix).


13

2.6 ENVIRONMENTAL COMPATIBILITY

2.6.1. EFFECT ON AQUATIC ECOLOGICAL SYSTEMS

Substances of all construction material are principally able to migrate into the environment. Particularly in the

field of hydraulic engineering, it is very important to evaluate if the aquatic ecological system is affected by such

a migration. This aspect was considered from the beginning of the development of this material. Elastocoast was

tested on six different water organisms (DIN 38412 and DIN 38415; see appendix). These extensive toxicological

studies support the conclusion that there is no expected effect on organisms living in the ecosystem water.

Studies undertaken at the SGS Institute Fresenius are confirming this conclusion (see reports in appendix).

2.6.2. RECOLONIZATION OF FLORA & FAUNA ON ELASTOCOAST REVETMENTS

Two pilot sites have been installed in 2007 in the Netherlands at Oosterschelde-Zuidbout and Petten.

Colonization by flora and fauna on these Elastocoast revetments has been monitored by University of

Amsterdam in cooperation with the engineering office ARCADIS (Early Colonization of Littoral Communities

on Polyurethane Coated Substrates - A Filed and Laboratory Study; Loock, M.; UV Amsterdam; 2008).

PROJECT ZUIDBOUT

On the Elastocoast layer the main colonized species Blidingia minima, and Enteromorpha compressa have settled on

some rocks. Full-grown Fucus spiralis shoots have also occupied some patches. Snails were found in large

amounts, especially just below the vegetation zone. They are probably feeding on the algae, which may have

caused the boundary to move upwards.


14

PROJECT PETTEN

The dyke near Petten is completely overgrown with algae. Blidingia minima and a brown-algae (probably a

Fucoid) are the main species found here. There is no difference in coverage percentages anymore, but it seems

that some areas are mainly covered with the brown algae, and other areas more with Blidingia minima. Birds, such

as the common oystercatcher (Haematopus Ostralegus) and the seagull (Larus spp.) forage on the revetment.

Fucoid species play a key role in the marine littoral environment, they are the most dominant but also very

vulnerable for change. The formation of a dense Fucoid canopy (such as seen in the original vegetation on the

Zuidbout) can be a good indicator of a stable community. When this is not the case it may indicate that full

community recovery may take longer. This study mainly is focused on algae but also snails and other animal

colonization. They can provide a food source for larger animals, making full community recovery possible.

LABORATORY EXPERIMENTS

Different stone substrates have been coated with Elastocoast and incubated in an algae mix (amongst others

Nitzschia (diatom), Synechococcus (cyano-bacteria), Leptolyngbia (cyano-bacteria), Pseudoanabeana (cyano-bacteria)).

After 27 days of incubation, algae had grown and all stones had visible algae attachment (see Fig. 2.6.2.7.). A

biofilm of different species (see Fig. 2.6.2.8) had formed on the water surface and the stones.


15

SUMMARY

This study examined the recovery and growth during the winter of 2007-2008 of the biological community on

two dikes in the Netherlands which were refurbished with Elastocoast at the beginning of the storm season, and

describes an algal colonization experiment done with Elastocoast in the laboratory.

In the field, 4 months after the construction of the Elastocoast top layer, dike vegetation has returned, though

strongly zonated and leaving large patches without any vegetation. Main algal species are Enteromorpha minima

and Fucus spiralis. Animals found on the Elastocoast layer mainly consisted of Littorina sp. and Patella Vulgata.

The Elastocoast pilots in the field were examined for 25 weeks and it is expected that the biological community

will recover further when given enough time.

The laboratory experiment showed that colonization by micro-algae under favorable circumstances can be fast

and substantial, by numerous micro algae and animals.


16

Elastocoast therefore seems to be a material which allows fast community recovery according to the typical

vegetation of that area. It can be concluded that Elastocoast is a suitable material for algal attachment.

Due to the transparency of the Elastocoast material the coated stones keep their natural colour and appearance.

Consequently Elastocoast revetments integrate much better into the landscape compared to concrete or bitumen

based constructions. On top it is possible to replant Elastocoast revetments with grass or plants by insert of earth

and seed.

2.7 END OF LIFETIME AND DISPOSAL

At the end of its lifetime the composite of cured PU and stones can be handled as non hazardous waste.

According to European Waste Catalogue EWC 07 02 13, separately both cured PU and stones are non hazardous

waste as well. As demolition waste with content of less than 5 Vol % PU the EWC 170107 or 170504 (mix of

concrete, bricks, tiles, ceramic : recycling as building material is possible) or in case of more than 5 Vol% the EWC

170904 (mix of construction and demolition disposal : waste disposal possible or recycling after burning as

building material is possible) can be applied. A possible recycling opportunity is to use the composite PU/stones

for use in road construction.

2.8 ECO-EFFICIENCY

The aim of the eco-efficiency analysis is to compare products or processes. This involves carrying out an overall

study of alternative solutions to include a total cost determination and the calculation of ecological impact over

the entire lifecycle. The alternatives are compared on the basis of the same customer benefit.


17

Thus, based on a 20000 m 2 project Elastocoast versus traditional coastal protection methods such as concrete and

Open Stoned Asphalt (O.S.A.) were analyzed concerning their Eco-efficiency (ISO 14040).

First, the environmental impact of the different alternatives is calculated based on six categories.

0,00

The combination of these individual data provides the total environmental impact of the alternative systems.

Facts:

o O.S.A. has the highest impact in the categories energy consumption due to high

consumption of fuels and energy for bitumen production, processing and energy content of

bitumen itself

o Concrete has the highest impact in all remaining categories. Resources consumption is high

mainly due to high construction masses of cement and stones extraction. Risk potential is

originated from the higher amount of stones and cement used and higher number of working

hours in the construction site: both aspects have high impact on industrial accidents. The high

toxicity potential is based on toxicity of materials used in the pre-chain and labeling (risk

phrases) of the mortar

o Land use is the only category where Elastocoast has an higher impact due to cultivation of

used renewable resources (fatty acid esters)

o In all other categories Elastocoast has the lowest impact on environment

At the same time, all the various costs incurred in manufacturing or using the products are calculated for each

alternative. The economic analysis and the overall environmental impact are combined in the eco-efficiency

portfolio.


18

Facts:

o Elastocoast is the alternative with highest eco-efficiency

o Concrete is by far less eco-efficient

2.9 COST EFFECTIVENESS

The projects showed that Elastocoast is cost effective and competitive. The basic cost points in an evaluation of

the coastal protection structure are transport, prices for raw materials, simple installation and processing of the

construction materials. These points are even more important if the construction site is located in a hard-to-reach

place on the main land and on isles and holms where the construction materials have to be transshipped several

times.

The high porosity and high load-bearing ability of Elastocoast results in substantially lower layer thicknesses of

the revetments constructed with Elastocoast. This may rise by up to 50% compared to conventional revetments.

Furthermore, gravel of smaller grain size (20 60 mm) can be used and reinforced whereas revetments based on

bitumen or concrete grout require hydraulic gravels of between 300 and 500 mm. Thus substantial cost savings

with regard to transportation and processing of construction materials will overcompensate the additional cost

for the PU bonding agent. This cost advantage is about 20-30% which leads to a relief of the public budget. The

way of applying Elastocoast revetments does not only result in higher security but also in a clear relief of the

budget/public funds in coastal protection, and therefore additional financial capital that may be used for further

important measures in this field.

-1,0

1,0

3,0

-1,01,03,0

costs (norm.)

en

vir

on

me

nta

lim

pa

ct

(no

rm.)

O.S.A. Elastocoast Concrete


19

3

ProjectnameYear of

constructionArea [m

2] Country Responsible Authority

Hamburger Hallig 2004 120 Schleswig Holstein (DE) LKN

Sylt Ellenbogen 2005 270 Schleswig Holstein (DE) LKN

Holm Grde I 2006 500 Schleswig Holstein (DE) LKN

Holm Grde II 2007 3000 Schleswig Holstein (DE) LKN

Sylt Munkmarsch 2007 1500 Schleswig Holstein (DE) LKN

Zuidbout 2007 500 NL Rijkswaterstaat

Petten 2007 500 NL Rijkswaterstaat

Fighting Island 2007 100 CAN ERCA

Bridge K45 2007 150 Schleswig Holstein (DE) LKN

Overtopping Testfield 2008 100 NL Rijkswaterstaat

Holland on Sea 2008 300 UK Tendring Council

Nordstrandischmoor 2008 1800 Schleswig Holstein (DE) LKN

Langeness 2008 3000 Schleswig Holstein (DE) LKN

Canal de Tancarville 2008 100 Frankreich Port Auth. Le Havre

Amrum 2008 1500 Schleswig Holstein (DE) LKN

Total 13440


20

HAMBURGER HALLIG (DE)

The coastal protection structure built in 2004 is located at the west side of the North Sea holm and is flooded even

in case of low storm tides and exposed to heavy wave impacts. The structure protects the direct area located

behind the reinforced shore line against erosion due to breaking water. Without such a break-water construction

far-reaching scouring may occur. In previous years attempts were made to stop these erosions by reinforcing the

surface of the area. However, this resulted in a shift of the damage towards the inside of the holm. Therefore, a

revetment reinforced by means of colloidal cement has been built in large areas in order to avoid retrograde

erosion. In cooperation with LKN Husum the existing coastal protection structure was expanded by realizing the

new construction method and using Elastocoast as a pilot field.

In order to provide the proof of steadiness and erosion resistance of Elastocoast revetments, laser surface scans

were applied to the pilot project by TUHH in October 2005 and March 2007 and validate the stability of

Elastocoast revetments (see 2.4.4. Monitoring).

Location: German North Sea coast, Schleswig-Holstein

Year of construction: October 2004

Realization: Martin Limbrecht GmbH & Co

Competent authority: Schleswig-Holstein Agency for Coastal Defense (LKN)

Planning: TU Hamburg Harburg (TUHH)

Area: approx. 120 m2

Task: Protection against scouring by wave impact

behind the reinforced coastal line

Construction: Breakwater revetment built of iron silicate stones and

Elastocoast on gravel core and geotextile

Bonding agent: Elastocoast 6551/100; 1 t


21

SYLT ELLENBOGEN (DE)

The project area is located at the northern end of the island of Sylt at the western coast of the Ellenbogen (Sylt

Elbow). The Elastocoast revetment built in September 2005 is directly connected to an existing protective

construction made of natural basalt stones. Two cement grouted revetments have not been able to resist the wave

pressure impacts at this exposed place and failed immediately after construction in 2002 and 2007. The test field

is surrounded by existing old and heavily damaged sheet pile walls.

Location: Northern end of Sylt Island at the west coast of the Ellenbogen

German North Sea coast, Schleswig-Holstein

Year of construction: September 2005

Realization: Martin Limbrecht GmbH & Co

Planning: TU Hamburg Harburg (TUHH)

Area: approx. 270 m2

Task: Securing the beach against sand erosion

Construction: Revetment made of iron silicate stones; geotextile



22

HALLIG GRDE I (DE)

Hallig (holm) Grde is located at off the North Sea coast of Germany. The coastal protection structure was built

in the same way as the project Hamburger Hallig where Elastocoast was built on a gravel core and geotextile.

2This project is no more a pilot project as an area of approx. 500 m is protected. Due to the simple processing, the

employees of LKN authority were able to install the construction after a one-day briefing on their own.

Location: Southwest of the Hallig Grde


Year of construction: July 2006

Realization:

Competent authority:

Planning:

Area: 500 m2


Construction: Revetment built of granite gravel (50/60mm) and

Elastocoast on gravel core and geotextile base



23

HALLIG GRDE II (DE)

Due to the successful construction in 2006 by the LKN Husum the Elastocoast breakwater revetment was

extended from 80 m to 500 m. This coastal protection system was presented to the public worldwide amongst

others Rijkswaterstaat (RWS) and U.S. Army Corps of Engineers (USACE) within the framework of an on-site

conference. The news agency Husumer Nachrichten reported (see addendum).

Location: Southwest of the Hallig Grde


Year of construction: June 2007

Realization:


Planning:

Area: 3000 m2



Elastocoast on gravel core and geotextile base

Bonding agent: Elastocoast 6551/100; approx. 23 t


24

SYLT MUNKMARSCH (DE)

At the beginning of September 2007 130 m of a coastal protection construction located at the tidal side of Sylt

Munkmarsch and heavily destroyed by the storm season 2006/2007 was repaired with approx. 11 t Elastocoast.

The realized slope of 1:2 of the revetment construction was exceptional here and would not have been possible to

be realized by means of conventional coastal protection measures. Due to this steep slope of 1:2 the area to be

secured could be clearly reduced.

Location: Sylt Munkmarsch



Realization:


Planning:

Area: 1500 m2

Task: Protection against wave impact and retrograde erosion


Elastocoast on gravel core and geotextile base;

toe protection by piling



25

ZUIDBOUT - OOSTERSCHELDE (NL)

The test field is located in the south of Rotterdam on an embankment within the tidal bay Oosterschelde. Three

different revetment thicknesses of 10, 20 and 30 cm were built. To the surprise of Rijkwaterstaat, even the

thinnest revetment layer of 10 cm resisted the storm season 2007/2008. The detailed monitoring in correlation

with detected wind speeds and water levels has been executed by TU Delft in cooperation with engineering

office ARCADIS (see 2.4.4. Monitoring) and validates the steadiness of Elastocoast revetments.

The recolonization of flora and fauna was monitored by UV Amsterdam showing that even after a short time of

two months a dense population of algaes and snags settled on the revetment (see 2.6.2.).

Location: Zuidbout at Oosterschelde (NL), North Sea


Realization: Oohm-Hesselberg-Hydro

Competent authority: Rijkwaterstaat

Planning: Arcadis NL

Area: 500 m2

Task: Test field

Construction: Revetment 10 cm, 20 cm, 30 cm; without

geotextile base, 20/40 mm limestone

Bonding agent: Elastocoast 6551/100; 3.5 t


26

NOORD PETTEN (NL)

A further pilot project was realized also in collaboration with the competent authority Rijkswaterstaat, the

engineering office Arcadis and the construction company Oohms-Hesselberg-Hydro in October 2007 in Noord

Petten, Netherlands. Due to the critical tides, a time slot of only 2 hours was given to install the Elastocoast

revetment. Despite these difficult conditions the work could be completed within 2 days. The thickness of the

three revetments layers was 10, 20 and 30 cm respectively. To the surprise of Rijkwaterstaat, even the revetment

layer of 10 cm resisted the storm season 2007/2008.

The recolonization of flora and fauna was monitored by UV Amsterdam showing that even after a short time of

two month a dense population of algaes and snags settled on the revetment (see 2.6.2.).

Location: Groyne near Petten (NL), open North Sea


Realization: Oohm-Hesselberg-Hydro

Competent authority: Rijkwaterstaat

Planning: Arcadis NL

Area: 500 m2

Task: Test field

Construction: Revetment 10 cm, 20 cm, 30 cm; without

geotextile base, 20/40 mm limestone



27

SLOPE PROTECTION ROAD BRIDGE K45 (DE)

Two embankments at the road bridge K45 were constantly eroded due to slumping. This road bridge had been

protected by concrete fixed stone blocks that had to be repaired every year. In December 2007 the slope was

reinforced by Elastocoast. Even at temperatures below 5C the material could be processed in three hours

without any problems.

Location: K45 Lecker Au near Niebll; Schleswig-Holstein

Year of construction: December 2007

Realization: Martin Limbrecht GmbG & Co

Competent authority: State Agency for Road construction (Landesbetrieb fr

Straenbau) Flensburg

Planning: State Agency for Road construction (Landesbetrieb fr

Straenbau) Flensburg

Area: 150 m2

Task: Embankment protection

Construction: Granite gravel (50 60 mm) reinforced with Elastocoast,

geotextile base,



28

FIGHTING ISLAND (CAN)

Fighting Island is an island of 600 ha in Canada surrounded by the Detroit River and bordering the U.S. State

Michigan. A test field of approx. 100 m2 was installed in September 2007. This was the first Elastocoast project

outside of Europe. A mixer with automatic feed that was provided specifically for this purpose was used

successfully. Approx. 1/3 of the area was built into the water. This Elastocoast revetment resisted the first ice

loads in winter 2007/2008.

Location: Fighting Island (Canada) at the Detroit River


Realization: J & J Marine Co.

Competent authority: Essex Region Conservation Authority (ERCA)

Planning: BASF Corporation

Area: 100 m2

Task: Riverbank protection

Construction: Revetment reinforced with Elastocoast; geotextile base



29

EMBANKMENT PROTECTION LEMFRDE (DE)

At the company site of Elastogran GmbH in Lemfrde a processing method was tested that enables the mixing

and output of huge amounts of Elastocoast-stone-mix for a size of 4-8 m3 in a very short time. For this purpose a

typical concrete mixer truck was successfully used. Approx. 4 m3 could be built in less than 5 minutes.

Location: Lemfrde; Elastogran company site


Realization: Elastogran GmbH

Area: 50 m2

Task: Test field

Construction: Sandstone from piesberg 20/40 reinforced with Elastocoast,



30

EMBANKMENT PROTECTION CANAL DE TANCARVILLE (F)

Embankment protection measure alongside a canal with 15 cm layer thickness with geotextile protecting the

sandy subsoil from undercutting. Gabions to protect the toe of the slope were set on the first 10m. The following

10 m of the revetment had no gabions on the toe but instead of that a 40 cm layer of Elastocoast built-in below

water level up to about 1 m in depth. This was done to fix the geotextile to the ground and avoid undercurrents,

eroding of the embankment beneath the revetment.

Location: Canal de Tancarville, Le Havre, Normandy

Year of construction: May 2008

Realization: SNV Maritime

Competent Authority: Independent Port Authorities Le Havre

Panning: SNV Maritime

Area: 80 m2

Task: Above water build with 15 cm layer with gabions, under water build

without gabions as slope protection

Construction: Lime stone reinforced with Elastocoast next to a lose stone slope

protection measure of > 50 cm layer thickness



31

REVETMENT HOLLAND ON SEA (UK)

The existing 8 year old Open-Stone-Asphalt (OSA) revetment had eroded due to heavy wave impacts and been

repaired with OSA 4 years ago. Again after that time the surface had failed showing substantial cavities and has

now been covered by a 20 cm layer of Elastocoast. The work was completed within 2 days on a slope of 1:3.

Location: Holland-on-Sea, Tendring Council, East Anglia

Year of construction: April 2008

Realization: Hesselberg Hydro Ltd. UK

Competent Authority: Tendring Council

Panning: Hesselberg Hydro Ltd. UK

Area: 300 m2

Task: Revetment installation; erosion protection of subsoil

Construction: Flint stone reinforced with Elastocoast on top of failed

existing Open-Stone-Asphalt revetment

Bonding agent: Elastocoast 6551/100; 1,5 t


32

NORDSTRANDISCHMOOR (DE)

The German holm Nordstrandischmoor is located in the North Sea in Schleswig Holstein. It is close to the holms

Grde and Langeness. Due to the continuous growth of the holm the height of the existing revetment had to be

adjusted. A breakwater revetment made with the Elastocoast system therefore was placed on the shore line. The

PU was delivered in 1 to IBC packaging and easy dosed by pumps.

Location: Holm Nordstrandischmoor (west end)

Year of construction: June 2008

Realization:


Planning:

Area: 1800 m

Task: Protection against erosion and wave impact

Construction: Revetment built of granite gravel (40/60 mm), reinforced with Elastocoast.

On gravel core and geotextile base.

Bonding: Elastocoast 6551/100; approx. 15 t


33

LANGENESS (DE)

The Holm Langeness is located in the North Sea in Schleswig Holstein. It is close to the Holms Grde and

Nordstrandischmoor. Due to the continuous growing of the holm the hight of the existing revetment had to be

adjusted. A breakwater revetment made with the Elastocoast system therefore was placed on the shore line.

Location: Holm Langeness (Mayenswarft)

Year of construction: August 2008

Area: 1500 m

Task: Protection against erosion and wave impact

Construction: Revetment built of granite gravel (40/60 mm), reinforced with Elastocoast.

On gravel core and geotextile base.

Bonding: Elastocoast 6551/100; approx. 13 t


Realization:


Planning:

34

4Another application area of Elastocoast is in road and lane construction. Because of the open-pored bonding of

stones and PU a drainage pavement system is generated. The composition is characterised by its high fraction of

rough fine stone grains, which provides an enormous contingent of adjacent hollow spaces. Through these

originated voids rain water can be drained off.

At the beginning of 2008 approximately 500 m2 of Elastocoast were laid as a drainage-pavement covering at the

Central Station in the middle of Chur (CH) Terraflexx realized this project successfully even at temperatures

around the freezing point.

Location: Chur in the canton Graubnden (CH); City Central Station

Year of construction: January 2008

Realization: Terraflexx Lenzburg (CH)

Planning: Schweizer Bundesbahn SBB

Area: 500 m2

Task: Forecourt of the railway station frequented by pedestrians and delivery traffic

Construction: Roadbed: 5-7 mm open-pored concrete

Coating: 1 -3mm granite reinforced by 5 Weight % of Elastocoast

Binding material: Elastocoast 6551/100; 1,5 t


35

In April 2008 a first test track was built within the framework of open-pored pavement. As a test field 30 m2 of

this product was coated on an access road, which is highly frequented by agricultural equipment and also by

light- and heavy-load-traffic. After promising results this test field will be extended to 600 m2 in July 2008 by a

local road construction company.

Location: Access road horse farm Horn; Lemfrde

Year of construction: April 2008

Realization: Wiebold Landschafts- und Straenbau GmbH

Planning: Wiebold Landschafts- und Straenbau GmbH

Area: 30 m2

Task: frequented by trucks, cars and agricultural equipment

Construction: Roadbed: 20-60 mm compacted gravel

Coating: 1-3 mm Piesberger particulates reinforced with Elastocoast

Binding material: Elastocoast 6551/100; 0,2 t


36

The Wyandotte site of BASF Corporation (US) is located on the banks of the Detroit River approximately 20 miles

south of the city of Detroit, MI. A porous pavement parking lot and sidewalk were installed with the use of

successfully evaluated continuous processing equipment capable of delivering 12 m3/hr. during construction.

Location: BASF Corporation, Wyandotte, MI

Year of construction: May 2008

Realization: Debacker’s Lawn Care and Maintenace Co

Planning: BASF Corporation

Area: 700 m2

Task: Porous pavement parking area and sidewalk

Construction: mixed aggregate, approximately 6 10 mm

Binding material: Elastopave (TM) 621001


37

In the US, a parking lot was built with the Elastocoast system (Elastopave) using a continuous process. The

installation was successful with ca. 40t of gravel placed within 4.5h. The machine was the smallest unit available

from the supplier (Cemen tech, Inc.). It is a light weight, easily maneuverable model. Using a larger machine of

the same type will lead to much higher outputs and shorter installation times.

Location: USA- Georgia

Year of construction: July 2008

Realization: Local contractor

Competent authority: Local

Planning: Unspecified

Area: 500 m

Task: Parking lot

Construction: Structure made using granite gravel and recycled glass (3/8-1/4 inch),

reinforced with Elastocoast and a polyethylene grid

Bonding: Elastocoast (US-equivalent); ca. 1.8t


Application of PUR-revetment Compared to That of Open Stone Asphalt Revetment on the project of Sylt

Hindenburgdamm

Gu, D.; Verhagen, H. J..; TU Delft

38

DOCUMENTS

Test report (No. 331466) SGS Fresenius about the effect of Elastocoast on the water quality

Test report (No. 2548/07) STB Prfinstitut fr Baustoffe und Umwelt GmbH

Resistance to weathering Resistance to frost (DIN EN 13383-1 and 2 f. water construction stones)

Elastocoast ten point processing guideline

BIOPLASTICS Award Finalist 2007 of the European Plastics News

INTRON Baumaterialienbeschluss A839590/R20070342

Technical instruction sheet Elastocoast 6551/100

Material Connection

Evaluations of the Impact of Cured Elastocoast 6551/100 in Aquatic Ecosystems when Applied for River Bank

Protection

NEWSPAPER ARTICLES

Auf Hallig Grde wird neues Verfahren getestet Husumer Nachrichten June 6, 2007

Mit Kuststoffkleber dem blanken Hans trotzen Husumer Nachrichten July 9, 2007

Orkankleber schtzt Deiche Aktiv Wirtschatszeitung November 10, 2007

Im Verbund gegen Naturgewalten Umweltmagazin April Mai , 2008


39

PUBLICATIONS IN APPENDUM

Elastomeric Revetments A New Way of Coastline Protection

International Conference of Coastal Engineering (ICCE) 2006 San Diego, USA

Pasche, E.; Evertz, T.; Liebermann v., N. (TUHH)

Neue Wege bei der Verfestigung von Deckwerken

Wasser und Abfall 6/2007; Evertz, T.; Petersen, K.

Flexible Deckschicht schtzt Deiche

Deutsches Baublatt Nr. 320, May 2006

Wirksamer Kstenschutz mit Elastocoast

Fachmagazin Polyurethan, July/August 2007

PU-System Elastocoast aktiv im Kstenschutz

PU Magazin, 4/2007

Preliminary Study of PUR-Revetment Application

Gu, D.; Verhagen, H. J.; Ven van de, M.; TU Delft (filed for publication)

First Experience with Polyurethane reinforced Revetments in the North Sea of Schleswig-Holstein (Germany);

International Conference of Coastal Engineering (ICCE) 2008 Hamburg, DE

Mordhorst, A.; Beismann, P.; (LKN Husum), Evertz, T.; (Golder Assocoates GmbH)

PUBLICATIONS NOT IN APPENDUM

Early Colonization of Littoral Communities on Polyurethane Coated Substrates - A Filed and Laboratory Study;

Loock, M.; UV Amsterdam; 2008

Elastocoast Pilots in the Netherlands Storm Season 2007/2008 Bijlsam, E.; TU Delft 2008

Verfestigung von Deckwerken mit Polyurethan-Elastomere Deckwerde im Wasserbau

Dissertation (publication in 2008) Evertz, T. (TUUH with Prof. E. Pasche)


Application of PUR-revetment Compared to �at of Open Stone Asphalt Revetment on the project of

Sylt Hindenburgdamm

Msc. Dehua Gu

Delft University of TechnologyFaculty of Civil Engineering

Section of Hydraulic Engineering and Enviromental Fluid Mechanics

Application of PUR-revetment Compared to �at of Open Stone Asphalt Revetment on the project of

Sylt Hindenburgdamm

September, 2007

1Application of PUR-revetment Compared to �at of Open Stone Asphalt Revetment on the project of Sylt Hindenburgdamm

INTRODUCTIONThis report compares the application of PUR-revetment with that of open stone asphalt (OSA) revetment on the project of Sylt Hindenburgdamm; in which, the major concerned parameter is the layer thickness of Elastocoast and OSA. The major referred criterion is VTV 2004

1

.

According to VTV 2004, there are two methods to obtain the required layer thickness of OSA revetment for a certain boundary condition. One is to simply get it from a graph (see Fig. 2) which was derived by previous computer programs and relative data; the other one is to get it by calculations in computer program GOLFKLAP 1.2 (lastest version). Table 1 shows for what combinations of age and mortar percentage the simplified method is applicable (Step 3) and for what combinations the detailed method must be applied straightaway (Step 4); in which, the quantity of asphalt mortar used is taken as an indicator of the quality of open stone asphalt, because this determines how thick and durably the stones are enclosed.

GOLFKLAP is a computer program for the design and evaluation of an asphalt revetment at wave impacts. It calculates the bending stresses in the revetment due to wave loads and compares it with the failure stress to verify whether the construction will yield.

As we all know, wave loads at a revetment on sands can cause bending stresses in the material and destroy the structure. To calculate this bending stresses in GOLFKLAP, the revetment is schematized as an elastic beam supported by small springs; so the structure can be characterized by the layer thickness, the stiffness modulus, the fatigue strength of the material and the modulus of subgrade reaction; the wave impacts are schematized as a serie of triangular loads on the layer (see Fig.1). The properties of the materials made up of the revetment, which are necessary for the calculation and comparison can be obtained from laboratory tests.

1 De Veiligheid van de Primaire Waterkeringen in Nederland Voorschrift Toetsen op Veiligheid voor Detweede Toetsronde 2001-2006 (VTV) Januari 2004 Ministerie van Verkeer en Waterstaat

Negative deviation relative to mortar content agreed when laying

[percentage by mass]

Age (years)

0 - 5 6 - 10 11 - 15 16 - 20 > 20

0 - 0,5 3 3 3 3 4

0,6 - 1,0 3 3 3 4 4

1,1 - 1,5 3 3 4 4 4

1,6 - 2,0 3 4 4 4 4> 2,0 4 4 4 4 4

Table 1 Applicability’s requirement of aged open stone asphalt

Figure 1 Schematization of the revetment in GOLFKLAP

Application of PUR-revetment Compared to �at of Open Stone Asphalt Revetment on the project of Sylt Hindenburgdamm

2

Due to the similar structures of Elastocoast and OSA, it is reasonable that GOLFKLAP can also be applied to PUR-revetment in a relatively conservative way based on the available information of Elastocoast so far. The detail reasons and derivations of applying GOLFKLAP to Elastocoast are given in a recently published study report

2

, and are not explained in this report.

METHODSTable 1 suggests that for the project of Sylt Hindenburgdamm, graph in Fig. 2 should be applied to obtain the minimum thickness of (new) OSA; the minimum thickness of Elastocoast can be calculated in GOLFKLAP.

The minimum thickness of OSAIn Figure 2, the horizontal axis is significant wave heights, the vertical axis is the thickness of OSA layer. Two kinds of sub-layer are available for reference, sand and clay; for each sub-layer, some corresponding inclination curves or lines are provided to derive the required minimum thickness according to the significant wave heights. In this case, the sub-layer is sand and the inclination is 1:3. So the thickness should be derived from the lowest line with ‘filter zandasfalt‘ and ‘overig‘ (means other slopes). As a result, the required minimum layer thickness of OSA is about 0.13 m at Hs=1.5 m and 0.15 m at Hs=2 m.

The calculations of ElastocoastIn GOLFKLAP, the major input data is stiffness and fatigue coefficients of the material, the wave loads and assumed layer thickness of the material; the output data is miner sum, of which the critical value is 1. In another word, if the output value of miner sum is smaller than 1, the assumed input thickness satisfies the requirement; while if the output value of miner sum is larger than 1, then the construction of the assumed layer thickness may fail.

In the case of Sylt Hindenburgdamm, the significant wave height is 1.5 m which is not quite high; and in GOLFKLAP, the minimum value of input thickness is 0.1m (reasonable due to the practical reason). As a result, with input values of Hs=1.5 m and even only 0.1 m layer thickness, the miner sum value of PUR-revetment were still much less than 1. The parameters and results are given in Table 2, Figure 3 and Figure 4.

2 Gu, D. 2007. Some Important Mechanical Properties of Elastocoast for Safety Investigation of Dikes (VTV 2004). Minor Msc. thesis, Department of Civil Engineering, Delft University of Technology, Delft, The Netherlands.

Figure 2 Design graph of OSA revetment


Elastocoast

Slope inclination 0.33

Bearing capacity of sub-layer (Mpa/m) 100 (sand)

Stiffness (Mpa) 3000

Poisson 0.35

Significant wave height (m) 1.5

Wave periods (T=3.5√Hs ,s) 4.29

a 6

log(k) 3.3

Assumed thickness (m) 0.1Miner sum 0.008

Table 2 The parameters for the first calculation of PUR-revetment in GOLFKLAP

Figure 3 Calculation results of PUR-revetment at Hs=1.5 m in GOLFKLAP-part 1


4

Apparently, the calculation results of 1.5 m wave height were not very ideal for the comparison because the minimum thickness of PUR-revetment was not obtained due to the limitation of assumed thickness. So another calculation was carried out to improve the comparison. The basic idea was to assume the thickness of PUR-revetment to be an acceptable practical value such as 0.15 m, then try different wave heights in the calculations until the value of miner sum is around 1. As a result, the maximum wave impacts at which 15 cm PUR-revetment can withstand was obtained. The parameters and results are given in Table 3, Figure 5, Figure 6.

Elastocoast

Slope inclination 0.33

Bearing capacity of sub-layer (Mpa/m) 100 (sand)

Stiffness (Mpa) 3000

Poisson 0.35

Significant wave height (m) 5.2

Wave periods (T=3.5√Hs ,s) 7.98

a 6

log(k) 3.3

Assumed thickness (m) 0.15Miner sum 1.003


Table 3 The parameters for the second calculation of PUR-revetment in GOLFKLAP


6

CONCLUSIONSIt was found that at the same wave impacts of Hs=1.5 m, the required minimum thickness of OSA revetment is 0.13 m and that of PUR-revetment is less than 0.1 m. Moreover, with same thickness of 0.15 m, the OSA revetment can withstand wave impacts of Hs=2 m but the PUR-revetment can withstand wave impacts of Hs=5.2 m.

In view of the calculation results based on the current available information of Elastocoast, the required minimum thickness of PUR-revetment is smaller than that of OSA revetment at the same wave loads. In another word, PUR-revetment is stronger than OSA revetment from the mechanical point of view.

Elastogran GmbHEuropean Business Management Case & Specialties

Elastogran GmbH · Postfach 1140 · 49440 Lemförde · Germany

Elastogranstraße 60 / 49448 Lemförde Postfach 1140 / 49440 Lemförde Telefon +49 5443 12-0 Telefax +49 5443 12-2932 E-Mail [email protected]

Bankverbindung: Commerzbank AG, Osnabrück (BLZ 265 400 70) Kto.-Nr. 53 56001/00 IBAN: DE 36 2654 0070 0535 6001 00 S.W.I.F.T.-Code: Cobadeff 265

Sitz der Gesellschaft: 49448 Lemförde Geschäftsführer: Wolfgang Stegh (Sprecher); Uwe Hartwig Aufsichtsrat: Jacques Delmoitiez (Vorsitzender) Registergericht: Amtsgericht Walsrode Eintragungsnummer: HRB 100087

Elastocoast® 10 point processing advice

11.01.2008AC/M / A10 Denis Vugrek Tel.: +49 5443 12- 2859 Fax: +49 5443 12- 2936 E-Mail:[email protected]

The following topics are thought as a technical advice to apply Elastocoast® correctly.

Disregarding these topics leads to a reduction in quality which means the product strength

will be reduced and the lifetime also.

Prior to processing the employees have to be informed about health and safety (i.e. safety

data sheet, technical data sheet and general processing guidelines).

Conditions for Elastocoast® processing:1. Dry weather

- no rainfall - outdoor temperature min. 10 °C

2. Gravel has to be delivered dry (and preferred washed)- free of smut

3. Tumbler has to be dry 4. Subsoil preparation corresponding to the specifications 5. Determine the needed amount of gravel and fill it into the tumbler.

example: 33 kg PUR / 1m3 gravel (about 3 % by volume)

6. pour Iso (B)-component into Poly(A)-component and mix it - follow safety data sheet instructions - wear protective clothing !

7. Give mixed „resin“ to the gravel and start the tumbling process 8. Dump the gravel-resin mixture at the planed place and spread it out. 9. Scatter sand over the revetment. 10. If there is a process stop, clean the tumbler by mixing clean and dry gravel only

Client ARCADIS Regio B.V. attention of Mr. C. Lazonder Post-office box 4205 3006 AE ROTTERDAM

Our reference A839590/R20070342/UHo/eal

Authorisation van Selst

Date November 21, 2007

Author dr. U. Hofstra

ENVIRONMENTALLY HYGIENIC QUALITY EXAMINATIONS ON A REVETMENT WITH ELASTOCOAST

Revetment test in the scope of resolution about constructional material

Summary

INTRON has conducted a environmentally hygienic examination of a revetment affixed with Elastocoast, by order of ARCADIS B.V. On September 13, 2007 several cured samples were taken by an INTRON employee during constructional works, and were examined later on. This revetment is located on an expanded levee in Oosterschelde near Ouwerkerk.

The results of the examined samples were within the limit values from the resolution about constructional material.

During the examinations of the organic part the spores of mineral oils and toluol were found. Those did probably not originate from the Elastocoast samples.

In the leaching test with acid the inorganic part of the samples was measured. Observed leaching of molybdenum and fluorides comes probably from the limestone used in the construction.

ENVIRONMENTALLY HYGIENIC QUALITY EXAMINATIONS ON A REVETMENT WITH ELASTOCOAST

Revetment test in the scope of resolution about constructional material

Summary

INTRON has conducted a environmentally hygienic examination of a revetment affixed with Elastocoast, by order of ARCADIS B.V. On September 13, 2007 several cured samples were taken by an INTRON employee during constructional works, and were examined later on. This revetment is located on an expanded levee in Oosterschelde near Ouwerkerk.

The results of the examined samples were within the limit values from the resolution about constructional material.

During the examinations of the organic part the spores of mineral oils and toluol were found. Those did probably not originate from the Elastocoast samples.

In the leaching test with acid the inorganic part of the samples was measured. Observed leaching of molybdenum and fluorides comes probably from the limestone used in the construction.

Chemical Characteristics

Application

Solvent free, two component Polyurethane coating

Polyol-Component: Mixture of polyols and additives Iso-Component: Preparation containing diphenylmethane-diisocyanat (MDI) = IsoPMDI 92140

Elastocoast® 6551/100Page 1 / 3 Version 01 Date of issue: 16.10.2006

Technical Data Sheet

The type of supply for the components will be decided after consultation with our Sales Office

Supply

Polyurethane components are moisture sensitive. Therefore they must be stored at all times in sealed , closed containers.The A-component (Polyol) must be homogenised by basic stirring before processing.More detailed information should be obtained from the separate data sheet entitled "Information for in-coming material control, storage, material preparation and waste disposal" and from the component data.

Storage, Preparation

For processing follow the information provided by our technical adviser

Processing

The B-component (Isocyanate ) irritates the eyes, respiratory organs and the skin. Sensitisation is possible through inhalation and skin contact. MDI is harmful by inhalation. On processing these, take note of the necessary precautionary measures described in the Material Safety Data Sheets ( MSDSs ). This applies also for the possible dangers in using the A-component (Polyol) as well as any other components.See also our separate information sheet " Safety- and Precautionary Measures for the Processing of Polyurethane Systems." Use our Training Programme " Safe Handling of Isocyanate."

Possible Hazards

More detailed information is provided in our country -specific pamphlet

Waste Disposal

There are national and international laws and regulations to consider if it is intended to produce consumer articles ( eg articles that necessitate food or skin contact,toys etc. ) or medical objects out of Elastogran's products. Where these do not exist , the current legal requirements of the European Union for consumer articles as well as medical products should be sufficient. Consultation with the Elastogran Sales Office and our Ecology and Product Safety Department is strongly recommended

Consumer articles, medical products


Component Data

Unit Polyol-Comp Iso-Comp. Method

Density (25°C): g/cm³ 1.05 1.23 DIN 51 757

Viscosity (25°C): mPa·s 1800 200 DIN 53 018

Storage Stability (20 – 25 °C) months 12 6

Processing Data

Machine Processing

Unit Value Method

Mixing ratio Parts by weight Polyol-Comp. = 100 : Iso-Comp. = 50

Time of processing at 23 °C min. 20 Recommended processing temperaturePolyol-Component Isocyanate-Component

°C°C

10 - 30 10 - 30


Physical Properties

Unit Measured value Method

Hardness Shore D 70 DIN 53 505

Tensile strength N/mm² 22 DIN 53 504

Elongation % 20 DIN 53 504

Tear strenght N/mm 33 DIN 53 515

Density g/cm³ 1.1 DIN 53 420 The mechanical properties were measured by use of test specimen which were casted by hand stored for 28 days under standard climatic condition.

*) The quoted values are guide values. They do not represent a specification or guaranteed properties.

Elastogran GmbH Tel.: +49 ( 0 ) 5443-12-0 Fax: +49 ( 0 ) 5443-12-2020 Postfach mail: [email protected] 49440 Lemförde Internet: www. elastogran.com

® = registered trade mark of Elastogran The data contained in this publication is based on our current knowledge and experience. In view of the many factors that may affect processing and application of our product, this data does not relieve processors from carrying out their own investigations and tests; neither does this data imply any guarantee of certain properties, or the suitability of the product fora specific purpose. Any descriptions, drawings, photographs, data, proportions, weights etc. given herein may change without prior notice and do not constitute the agreed contractual quality of the product. It is the responsibility of the recipient of our products to ensure that any proprietary rights and existing laws and legislation are observed. (Date of publication).

PRELIMINARY STUDY OF PUR-REVETMENT'S APPLICATION / 1

INTRODUCTIONDuring these years more and more attentions have been paid to the protections of coastal and riverine areas due to the global warming and climate change; the appearance of PUR-revetment is one of the results of these attentions. This research is a preliminary study of the feasibility of PUR-revetment’s application.

Nowadays, various protection methods such as sediment supply, groynes, breakwaters and revetments have been applied to prevent bank and shore from erosions caused by waves and currents. A very simple example of a revet-ment is one layer of geotextile with crushed stones on top; besides loose rocks, other materials such as placed blocks, asphalt, grass and rigid structures are also popularly ap-plied for revetments; they can be not only applied individu-ally but also combined together. Recently polyurethane has been involved in the application of revetments as well.

Polyurethane (PUR) is a very well known material in plastic industry and applied for example in automotive, construc-tions, electronic segments as well as offshore oil and gas pipe coating industry. A special hydrophobic PUR-system (Elastocoast 6551/100) has been developed for revetment constructions in coastal protection: gravels of 20-60 mm are coated in a standard concrete mixer with about 1.8 % (by weight and depending on stone size) PUR; this PUR-stone mixture is then distributed on the slope as a 15-30 cm thick top layer of a revetment and starts to cure; one day later the PUR-stone is resilient and achieves its final strength after 2 days, namely a PUR-revetment is ready.

A PUR-revetment has a similar structure with that of open stone asphalt revetment (OSA revetment). Moreover, the structure of PUR-stone mixture is similar to that of open stone asphalt (OSA) as well. So this research is mainly based on the comparisons of PUR-stone to OSA and PUR-revetment to OSA revetment.

Some popular criterions of revetments and the compari-

sons of different applied materials are given in Table 1. In the column of PUR-stone, ‘part of study‘ indicates the studied aspects in this research; the question mark means the aspect was not studied in this research. Seven experi-ments have been done in this study; they were (standard) four-point bending frequency sweep test, (standard) mo-notonic three-point bending strength test, porosity of PUR-stone test, stability of unhardened PUR-stone on slope test, permeability of interface between PUR-stone and geotextile test, wave run-up test and relative resistance of PUR-stone and other materials to abrasive action test; additionally, some calculations were made in computer program GOLF-KLAP with the results of four-point frequency sweep test and three-point bending strength test to compare the minimum required layer thickness of PUR-revetment and OSA revetment at various wave impacts. At last, the final conclusions about the application of PUR-revetment were made.

METHODSAmong the seven experiments carried out in the study, the four-point bending frequency sweep test and monotonic three-point bending strength test were standard material property experiments; and the test results were applied in a computer program GOLFKLAP. The other 5 experiments were designed testes to study the performances of PUR-stone and PUR-revetment in hydraulic applications. In Table 2 a summary of the experiments done in the study is given.

Four-point Bending Frequency Sweep TestThe standard four-point bending frequency sweep test was carried out to obtain the stiffness of PUR-stone, which was necessary for the calculations in GOLFKLAP. The test set-up and applied apparatus are shown in Fig. 1 (in which the specimen on the apparatus was not PUR-stone).

The major set-up parameters of the test are given in Table 3; in which, 23 °C was chosen according to DIN EN ISO 291 (Normklima) for the convenience of comparison with

Criterion Type Loose rock Placed block Grass Rigid structure Asphalt PUR-stone

Accessibility - + + - + part of study

Construction and maintenance ++ 0 + 0 - part of study

Costs depends depends depends depends depends depends

Flexibility for subsidence ++ + ++ - + ?

Heavy loads + + - ++ ++ part of study

Landscape depends depends depends depends depends dependsSpace required 0 0 - ++ 0 0

PRELIMINARY STUDY OF PUR-REVETMENT’S APPLICATION

Dehua Gu, Henk Jan Verhagen, and Martin van de VenFaculty of Civil Engineering and Geosciences, Delft University of Technology,

PO Box 5048, 2600 GA Delft, The Netherlands [email protected], [email protected], [email protected]

Abstract: PUR-revetment is a newly developed method for hydraulic application. Its structure is similar to that of open stone asphalt revetment, but the crushed stones are glued by polyurethane (PUR) instead of bitumen. To study the feasibility of applying PUR-revetment, a research based on the comparisons between PUR-revet-ment and open stone asphalt revetment was carried out, for which, a standard four-point bending frequency sweep test, a standard monotonic three-point bending strength test, a porosity test, a stability on slope test, a wave run-up test, an interface permeability test, a relative resistance to abrasive action test and some cal-culations in GOLFKLAP were done. It suggests PUR-revetment is applicable in practice.

Keywords: PUR-revetment, PUR-stone, polyurethane, open stone asphalt revetment, bank protection

Table 1 Comparisons of different materials applied for revetments

2 / PRELIMINARY STUDY OF PUR-REVETMENT'S APPLICATION

the tests of polyurethane. The test procedure at a certain temperature of 5 °C is given as an example:

First all the beams were stored at 5 °C for at least 3 hours to assure the beams’ temperature were stable.

After conditioning, one beam was fixed on the fatigue test equipment, of which the temperature was also set at 5 °C, and kept for at least half-hour to assure the whole system including the closed environment of the equipment and the tested beam itself stayed at 5 °C stably.

Then the test was carried out with a frequency sweep in the order of 10, 8, 4, 2, 1, 0.5 and 10 Hz again; the

1.

2.

3.

last measurement of 10 Hz was done for checking the reliability of the test.

After this beam was tested at all the 6 frequencies, it was taken out and put at room temperature; then an-other beam was tested.

After all the beams had been tested at 5 °C, the experi-ment was repeated at 23, 35 and 50 °C.

The test results are shown in Fig. 2 and Fig. 3; in which, ‘B’ indicates specimens made of 10/14 mm black limestone, ‘Y’ indicates specimens made of 8/11 mm yellow limestone.

4.

5.

Experiment Type Main Task Main Apparatus Specimens

Four-point bend-ing frequency sweep test

Measured stiffness of PUR-stone at 5, 23, 35 and 50 °C, with frequen-

cies of 0.5, 1, 2, 4, 8 and 10 Hz

A 4-point bending beam fatigue testing equipment, computer

Three 50x50x400 mm beams made of 10/14 mm black limestone and three 50x50x400 mm beams made of 8/11

mm yellow limestone

Monotonic three-point bending strength test

Measured tensile bending strength of PUR-stone at loads of 0.5 mm/

min and 50 mm/min

A universal testing machine (UTM),

computer

Six 50x50x400 mm beams made of 10/14 mm black lime-stone and six 50x50x400 mm beams made of 8/11 mm

yellow limestone

Porosity testMeasured voids ratio of PUR-

stone made of two different grading stones

Sealed wooden mould, scale

Three 25x25x25 cm PUR-stone samples made of 16/32 mm yellow limestone and three 25x25x25 cm PUR-stone

samples made of 8/11 mm yellow limestone

Permeability test

Measured and compared the per-meability of the interface between PUR-stone and geotextile under water pressure of 1, 2 and 3 m

Pump, steel pipes, basin, hydraulic

pressure gauge and computer

20x20x10 cm, 20x20x20 cm and 20x20x30 cm PUR-stone samples made of 16/32 mm yellow limestone; 20x20x10 cm, 20x20x20 cm and 20x20x30 cm PUR-stone samples

made of 8/11 mm yellow limestone

Wave run-up test

Measured the roughness factor of PUR-revetment at regular wave

impacts

Flume, wave gauges and computers

A 1:3 slope of PUR-revetment made of 8/11 mm yellow limestone; A 1:3 slope of PUR-revetment made of 16/32

mm yellow limestone; A 1:3 smooth cement slope

Relative resist-ance to abrasive action test

Compared the resistance of several different materials against abrasive

action

An concrete mixer, cement and abrasive materials (two sizes

of granite)

2 PUR-stone specimens made of 8/11 mm yellow lime-stone, 2 PUR-stone specimens made of 16/32 mm yellow limestone, 3 aged open stone asphalt specimens, 3 artifi-cial basalt specimens and a colloidal concrete specimen

Stability on a slope test

Measured the critical slope angles causing unhardened PUR-stone

unstable on both woven and non-woven geotextile

A trolley, wood plate, crane, woven and

non-woven geotextile and camera

Some bulk unhardened PUR-stone of 16/32 mm yellow limestone

Table 2 Summary of the 7 experiments carried out in the study

Temperatures 5, 23, 35 and 50 °C

Frequencies 0.5, 1, 2, 4, 8 and 10 Hz

Peak micro-strain 150

Conditioning cycles 100

Stop test after 100

Table 3 Major parameters of 4-point bending frequency sweep test

B_5 B_5 B_5 B_5 B_5 B_5

B_23B_23 B_23 B_23 B_23 B_23

B_35B_35

B_35 B_35 B_35 B_35

B_50 B_50 B_50 B_50 B_50

Y_5Y_5 Y_5 Y_5 Y_5 Y_5

Y_23Y_23

Y_23Y_23 Y_23 Y_23

Y_35Y_35

Y_35Y_35

Y_35 Y_35

Y_50 Y_50 Y_50 Y_50 Y_50

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0.50 1.00 2.00 4.00 8.00 10.00

Frequency (Hz)

Stiff

ness

(Mpa

)

B_5 B_23 B_35 B_50 Y_5 Y_23 Y_35 Y_50

Figure 2 Stiffness results chart of 4-point bending frequency sweep test

Figure 1 The 4-point bending frequency sweep test apparatus


The number after ‘B’ or ‘Y’ indicates the temperature (°C).

The graph in Fig. 2 suggested that the stiffness of PUR-stone was somehow independent of frequency at a certain temperature. However, the influence of temperature was considerable; the stiffness values varied between 500 Mpa and 3000 Mpa from 5 °C to 50 °C. Moreover, the stiffness decreased with the increase of the temperature; and the difference of stiffness between 23 °C and 35 °C was similar to that between 35 °C and 50 °C; while the difference of stiffness between 5 °C and 23 °C was obviously larger.

Additionally the stiffness of PUR-stone also varied with type of stone. In general, the stiffness of PUR-stone made of 8/11 mm yellow limestone was higher than that of the PUR-stone made of 10/14 mm black limestone; it perhaps was a result of the different quality or grading width of these two types of stones (the density of 8/11 mm yellow limestone was about 1464 kg/m3 and that of the 10/14 mm black limestone was about 1380 kg/m3). Further studies need to be done to understand how the stiffness of PUR-stone is influenced by different stone qualities and sizes.

It was also found the differences of stiffness between these two types of PUR-stone became smaller at higher tempera-tures. It perhaps indicated that at higher temperatures, the influence of stone types was smaller.

The other test result was phase angle which was defined in the test program as Ф=360fs, in which,

f=load frequency (Hz)s=time lag between peak force and peak deflection at centre of beam (seconds)

Normally when the phase angle equals to zero degrees, the material has elastic behaviours; when it is between 0 and 90 degrees, the material is visco-elastic; when it is 90 degrees, the material is viscous.

In Fig. 3, the phase angles of two types of PUR-stone were close to each other. At 5, 23 and 35 °C both of their phase angles respectively remained stable basically around 1, 5 and 9 degrees with the margins of 2, 3 and 4 degrees. The results suggested PUR-stone was approximately a kind of elastic material at lower or normal temperatures. At 50 °C, the test results were neglected due to the error of meas-urements. The unreliable results at 50 °C were caused by the applied small forces which led to unsmooth force sig-nals; consequently it was difficult for the program to derive reliable values of phase angle based on these scattering signals.

On the other hand, the increasing phase angles with in-creasing temperatures might also suggest that PUR-stone became more visco-elastic at higher temperatures.

The main results of the four-point frequency sweep test were: the stiffness of PUR-stone depended on the tempera-ture, stone size and quality; at low temperature (5 °C), the stiffness of PUR-stone was lower than that of aged OSA (around 5000 Mpa); PUR-stone was more or less elastic.

Monotonic Three-point Bending Strength TestThe standard monotonic three-point bending strength test was a failure test carried out at room temperature (20-25°C) to obtain the tensile strength (and other data such as tangent stiffness). Four 10/14 mm black limestone beams and four 8/11 mm yellow limestone beams were tested at 50 mm/minute; two 10/14 mm black limestone beams and two 8/11 mm yellow limestone beams were tested at 0.5 mm/minute.

The tested beam was located in a universal testing machine (UTM); the fixture included two cylindrical supports com-bined with two metal plates and one load roller combined with one metal plate (See Fig. 4). The metal plates were used as the contact interfaces between the beam and the supports or load cell; because the surfaces of the beams were too rough for the cylindrical supports and load cell.

B_5

B_5 B_5B_5

B_23

B_23

B_23

B_23

B_23

B_23

B_35B_35

B_35B_35 B_35

B_35

Y_5Y_5

Y_5

Y_5

Y_5 Y_5

Y_23

Y_23

Y_23

Y_23 Y_23 Y_23

Y_35

Y_35

Y_35 Y_35

Y_35

Y_35

0

2

4

6

8

10

12

14

0.50 1.00 2.00 4.00 8.00 10.00

Frequency (Hz)

Phas

e an

gle

(Deg

)

B_5 B_23 B_35 Y_5 Y_23 Y_35

Figure 3 Phase angle results chart of 4-point bending frequency sweep test

Figure 4 Sketch of the monotonic three-point bending strength test set-up

Samples10/14 mm black limestone beams 8/11 mm yellow limestone beams

Placement Broke in the middle Placement Broke in the middle

Sample 1 Top surface upward No Top surface lateral Yes

Sample 2 Top surface lateral Yes Top surface lateral No

Sample 3 Top surface lateral No Top surface lateral No

Sample 4 Top surface lateral Yes Top surface lateral No

Sample 5 Top surface lateral Yes Top surface lateral YesSample 6 Top surface lateral Yes Top surface lateral Yes

Table 4 Records of the monotonic three-point bending strength test


In the progress of the test, the beams were numbered and their performances were recorded by words and photos; the photos of broken cross sections and broken positions were also taken. At the load of 50 mm/min, the beams bent a little at first and then broke suddenly after less than 20 seconds; at the load of 0.5 mm/min, the beams broke suddenly as well after about 20 minutes since the begin-ning of the tests. The details are shown in Table 4.

The test results are given in Table 5. Generally, the strength of 8/11 mm yellow limestone beams was larger than that of 10/14 mm black limestone beams; besides, the strength at higher loading speed was larger than that at lower load-ing speed.

Moreover, it was found during the test that sometimes the strength of PUR-stone did not depend merely on the bond-ing force of polyurethane between stones. In the test, yel-low beam 6 was protected particularly from being damaged by the underneath metal part of the equipment frame when the beam was broke and fell down; then the cross section was observed and several stones were found broken into two parts with intact bonding points (see Fig. 5). So it was concluded that the strength of bonding points sometimes was even bigger than the strength of stones.

The results of monotonic three-point bending strength test suggested that the strength of PUR-stone depended on the stone size and quality; the different bonding connections (structures) perhaps influenced the performance of PUR-stone. But the strength of PUR-stone was certainly higher than that of OSA which was around or less than 1 Mpa.

Porosity TestVoids ratio influences the resistance to abrasion, the dura-bility and other properties of a material. So a porosity test was done with 6 PUR-stone specimens and the volume of pores, namely the voids ratio, VIM was given by,

VIM=100(dm-da)/dm vol %

In which,

dm=density of the mixture without voids (kg/m3)da=density of the mixure with voids (kg/m3)

(The weight of polyurethane can be neglected)

In the test, in order to obtain the density of PUR-stone specimens without voids, the specimens were put into the water to get the volume of the specimens without voids by measuring the differences of weights.

The results were calculated by average values of the test data. According to the test results, there was no obvious difference of porosity between the PUR-stone specimens made of 16/32 mm yellow limestone and the PUR-stone specimens made of 8/11 mm yellow limestone (see Table 6). In another word, the porosity of PUR-stone was not quite relevant with the stone size and grading width, at least for grading width of 8/11 mm and 16/32 mm. This conclusion was an useful reference for making conclusions of permeability test.

The Stability of bulk Unhardened PUR-stone On Slope TestThe stability on slope test was designed to know how stable a pile of bulk unhardened PUR-stone was on a slope with a certain angle; because the major way of constructing PUR-revetment was tumbling the mixture and spreading it onto the slope. The interface applied in the test between PUR-stone and the wooden plate slope was two different types of geotextile—woven and non-woven. After the unhardened PUR-stone had been put onto the slope, the incline was adjusted gradually and smoothly in less than one minute so as to avoid the influence of different hard extents (started at 0 degrees at a speed of one degree per two seconds). The test set-up is shown in Fig. 6, in which, the camera was used to record the slope angles and time periods.

In the first test, a pile of bulk PUR-stone was tested on a piece of woven geotextile first and then tested again on a piece of non-woven geotextile; and this applied PUR-stone was tested about 10-15 minutes after being produced. To avoid the error due to the different hard extents of PUR-stone on the first tested geotextile and the second tested geotextile, the test was repeated by testing on the non-woven geotextile first and on the woven geotextile second; besides, the PUR-stone was tested directly after being pro-duced in the second test to check whether there was obvi-

Samples and loadsMax. loadax. load Displacement Sum Energyum Energy Etangent σ

[kN] [mm] [J] [Mpa] [Mpa]

Black, 10/14 mm, 50 mm/min, average of 4 beams 0.31 0.85 0.95 800.43 2.66

Black, 10/14 mm, 0.5 mm/min, average of 2 beams 0.26 1.27 0.94 615.77 2.23

Yellow, 8/11 mm, 50 mm/min, average of 4 beams 0.36 1.12 0.86 934.75 3.15

Yellow, 8/11 mm, 0.5 mm/min, average of 2 beams 0.26 1.45 1.11 686.78 2.24

Black, 10/14 mm, average of all 6 beams 0.29 0.99 0.95 738.88 2.51Yellow, 8/11 mm, average of all 6 beams 0.33 1.23 0.95 852.09 2.84

Table 5 Results of the monotonic three-point bending strength test

Specimens B1 B2 B3 S1 S2 S3

Dd (kg/m3) 1463 1427 1475 1425 1382 1393

Dw (kg/m3) 1912 1889 1919 1878 1852 1858

Porosity (-)orosity (-) 0.45 0.46 0.44 0.45 0.47 0.47

Bnumber=the symbol of 16/32 mm yellow limestone specimenSnumber=the symbol of 8/11 mm yellow limestone specimenDd=dry bulk densityDw=wet bulk density

Figure 5 Broken stones at the broken cross section of yellow beam 6 in the monotonic three-point bending strength test

Table 6 Results of the porosity test


ous influence of different hard extent. In these two tests, when the bulk PUR-stone started to move, it was consid-ered as ‘begin failure’; when the bulk PUR-stone spread completely on the slope, it was considered as ‘completely failure’.

The test results are given in Table 7. It indicated that on the woven geotextile, the bulk PUR-stone started failure at about 15 degrees slope and completely failed at about 20 degrees slope; on the non-woven geotextile, the bulk PUR-stone started failure at about 27 degrees incline and com-pletely failed at about 34 degrees incline.

The tests results suggested the types of geotextile influ-enced the stability of bulk unhardened PUR-stone on a slope; and bulk unhardened PUR-stone stayed more stable on a non-woven geotextile. Additionally, there was almost no difference between the first test results and the second test results, it indicated that a short delay between the production and the application had less influence as long as the interval was less than the requirement period (about 20 minutes). Considering the angles of 1:3 slope and 1:4 slope, which are popular slope angles of revetments, are about 18 degrees and 14 degrees, no big problem would be expected in the application of PUR-stone on revetments.

Permeability of the Interface Between PUR-stone and GeotextileAlthough the permeability of PUR-stone had already been proved to be significantly high, the extra polyurethane flowing onto the geotextile during producing should still be concerned since it might block the interface to some extent and then consequently influenced the permeability as well as stability of the whole structure. So this permeability test was designed to study the permeability of the interface between PUR-stone and geotextile. This experiment was carried out with different thick specimens made of two sizes’ stones at various water pressures. The permeability coefficient in this study was defined as,

K=Q/A (m/s)

In which,

K=the permeability coefficient,Q=the water discharge,A=the cross section area of flow path

Six different specimens were produced with PUR-stone, woven geotextile and wooden moulds. Every specimen was produced in a wooden mould with a piece of geotextile at bottom and was tested together with that geotextile. The test system shown in Fig. 7 was set up to measure the permeability of PUR-stone with geotextile at three differ-ent water pressures of 1, 2 and 3 m. The water pressure was generated by a pump and a vertical steel pipe. Various water pressures from 0.8 m to more than 3 m could be obtained by pumping different amounts of water into the vertical pipe; the amount of the water passing through a specimen could be calculated by measuring the variance of water volume in a basin of 21.9x1.35 m2. For each speci-men and water head, one test was done twice.

It was obviously shown in Fig. 8 the blocking situation of specimens made of 16/32 mm yellow limestone was much more serious than those made of 8/11 mm yellow limestone. It was probably due to the more contact points and surfaces between stones and polyurethane for the

First testWoven Start Begin failure Completely failure

Time 16:15:40 16:16:14 16:16:30

Angle (deg.) 0.0 14.8 18.9

Non-woven Start Begin failure Completely failure

Time 16:21:54 16:22:56 16:23:38

Angle (deg.) 0.0 27.2 34.7

Second testWoven Start Begin failure Completely failure

Time 17:53:58 17:54:32 17:54:46

Angle (deg.) 0.0 15.6 21.1

Non-woven Start Begin failure Completely failure

Time 17:45:34 17:46:30 17:46:50Angle (deg.) 0.0 27.2 33.0

Table 7 Results of stability on slope test

Figure 6 Stability of unhardened PUR-stone on slope test set-up

Figure 7 Permeability test set-up


specimens made of 8/11 mm limestone; and the flow path of polyurethane in a specimen made of smaller stones was believed to be much longer than that in a specimen made of larger stones.

The summary graph of test results is shown in Fig. 9; in which, ‘8/11 mm, 10 cm‘ meant 10 cm specimen made of 8/11 mm yellow limestone; the rest were analogically de-fined.

Fig. 9 suggests:

For 10 cm thickness, the permeability of the specimen made of 8/11 mm yellow limestone was similar with that of the specimen made of 16/32 mm yellow lime-stone.

For 20 cm and 30 cm thickness, the permeability of the specimens made of 16/32 mm yellow limestone was much bigger than that of the specimens made of 8/11 mm yellow limestone.

The differences of permeability between small stone specimens of various thickness were big than those of the different thick big stone specimens. So it was be-lieved that small stone specimens were more sensitive to the changes of thickness.

For small stones, the permeability of 20 cm specimen was bigger than that of 30 cm specimen, it was reason-able. However for big stones, the permeability of 20 cm specimen was a little bit smaller than that of 30 cm specimen.

There were several possible reasons of the phenomenon described in item 4. On one hand, when the specimens were produced, some polyurethanes flow down to the sur-face of geotextile and block the geotextile to some extent; so the permeability could be considerably influenced by these blocking points; moreover, this kind of situation of the big stone specimen was much more severe than the situation of the small stone specimen, and might cause the permeability of 20 cm big stone specimen to be obviously bigger than that of 30 cm big stone specimen. But on the other hand, the geotextile of the three big stone specimens were peeled off and compared together after the test; it was found that the polyurethane’s amount on the geo-textile of 20 cm specimen almost equalled to that on the geotextile of 30 cm specimen. Besides, it was also possible that when the thickness was larger than 20 cm, the perme-ability of the specimens made of bigger stones perhaps maintained stable or namely reached the limitation. Fur-thermore, the measuring error might also influence the test results especially for the big stone specimens; because the water discharge was bigger and so the waves in the basin were bigger which caused bigger measuring errors. In a word, it was hard to judge the influence extent of the extra polyurethanes based on the results obtained from this test.

The conclusions of the permeability test were: for different

1.

2.

3.

4.

thickness, the permeability of the interface between PUR-stone and geotextile was sensitive to the stone size; but the influence of the extra polyurethane on geotextile should be further studied.

Wave Run-up TestThe high permeability of PUR-stone can probably reduce the wave run-up (wave loads) on the revetment and this can be helpful to decrease the cost of the structure. So it is meaningful to design an experiment to make a quantita-tive analysis of the reductive effect. For that purpose, two experiments were done with two PUR-stone slopes, and one test was done with a smooth slope in a flume. The wave run-up was measured; then the roughness factor was obtained and evaluated by comparison with the roughness factor of other materials such as open stone asphalt.

The first test was carried out on an existing smooth cement slope in the flume, the second test with PUR-stone made of 16/32 mm yellow limestone and the third test with PUR-stone made of 8/11 mm yellow limestone were done in a wooden slope mould filled with sands, on which a piece of geotextile was placed and the top layer on the geotextile was PUR-stone; the sizes of the PUR-stone specimens were

Figure 9 Summary graph of permeability test results

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 1 2 3Water pressure (m)

Perm

eabi

lity

(m/s

)

8/11 mm, 10 cm

8/11 mm, 20 cm

8/11 mm, 30 cm

16/32 mm, 10 cm

16/32 mm, 20 cm

16/32 mm, 30 cm

geotextile

Figure 10 Specimens applied for wave run-up test

Figure 8 Blocking extents of 8/11 mm stone specimens (up) and 16/32 mm stone specimens (down)


about 210 x 75 x 10 cm (for 8/11 mm yellow limestone) and about 210 x 75 x 15 cm (for 16/32 mm yellow lime-stone) (see Fig. 10). Different regular wave loads (ξ=1.5-4, H/L=0.004-0.03; ξ=tan(α)/sqrt(H/L0), in which α=slope angle) were applied and the wave run-up was recorded by counting the run-up heights of ten continuous waves on the slope; for instance, if the highest point of one wave reached the middle area between the sixth line and the seventh line, 65 cm was recorded. At last, the results of these three tests were combined to obtain the reduction coefficients and roughness factor of PUR-stone.

The test results are shown in Fig. 11; in which, the horizon-tal axis is breaker parameter (ξ) and the vertical axis is the ratio between wave run-up height (Z) and wave height (H). Then the reduction coefficients of PUR-stone were obtained by comparing the values of Z/H between smooth slope and PUR-stone slopes. At last the roughness factor (γ) was calculated; the roughness factor of PUR-stone specimen made of 16/32 mm yellow limestone varied from about 0.7 to 0.9; the roughness factor of PUR-stone specimen made of 8/11 mm yellow limestone varied from about 0.8 to 0.9 (see Fig. 12).

In the test, it was also found under impacts of plunging waves (ξ=1.5-3), the reductive effects of PUR-stone speci-men made of 16/32 mm yellow limestone was better than that of PUR-stone specimen made of 8/11 mm yellow lime-stone (see Fig. 11). This phenomenon was perhaps due to the higher permeability of PUR-stone specimen made of 16/32 mm yellow limestone (see Fig. 9); because the type of plunging wave was different from that of surging wave, it led to different impacting effect and so the permeability of the top layer probably had bigger positive influence to the wave run-up reductive effect at impacts of plunging waves compared to the situation of surging waves. This point might also explain why the blue trendline of PUR-stone made of 16/32 mm limestone dropped rapidly than the

pink trendline of PUR-stone made of 8/11 mm limestone in Fig. 11 considering most of the applied higher waves were plunging waves.

Considering the roughness factor of open stone asphalt is about 0.9, the wave run-up reduction ability of PUR-stone is better than that of open stone asphalt; in Fig. 11, the roughness factors of grass, colloidal concrete, open stone asphalt, basalaton and rubble mound of rock are included for reference. By comparisons, the test results suggested the roughness factor of PUR-stone was more or less lower than all the other materials except rubble mound of rock.

Relative Resistance to Abrasive Action TestSince the strength of PUR-stone is much higher than that of open stone asphalt, the erosion of wave impacts is prob-ably not a major issue for PUR-stone. Nevertheless, the in-fluences of sands and rocks in the currents should be con-cerned since the crash and abrasion may lead to failures.

A relative comparison method was chosen because it fit the target of this project and could provide intuitional results. The test was done in a concrete mixer, of which the inboard surface of container was covered with different specimens, which were two PUR-stone discs made of 16/32 mm yellow limestone, two PUR-stone discs made of 8/11 mm lime-stone, three artificial basalt discs, one colloidal concrete disc and three open stone asphalt discs; the thickness of all these discs was about 10 cm. By rotating the container filled with water and two sizes of granite stones which were applied as abrasive materials, the relative abraded extents of the specimens were observed after two days’ testing (see Fig. 13).

Artificial basalt specimens

There was almost no obvious abraded situation observed on the surface of all the three artificial basalt specimens; only few cement was eroded, some parts of the small stones on top were exposed and round; a corner of one specimen had a small abraded hole.

Colloidal concrete specimen

The colloidal cement on the surface of the specimen was completely moved away; the aggregates on the top were exposed, round and slick; but the whole surface of the specimen still kept almost flat and no obvious hole was ob-served. In another word, only few stones was lost. On the surface, the distance between the lowest point and highest point was less than 1 cm. Most of the gaps among the ag-gregates on the surface were filled by the small abrasive materials; due to the strength of granite, it might reduce the abrasive effect to some extent.

PUR-stone specimens made of 8/11 mm yellow lime-stone

Some stones were moved away from the specimens and

•

•

•

Figure 12 Results of wave run-up test (γ-H/d)

Figure 13 Set-up of relative resistance to abrasive action test

Figure 11 Results of wave run-up test (Z/H-ξ)

1.5

2.0

2.5

3.0

3.5

4.0

1.0 1.5 2.0 2.5 3.0 3.5 4.0ξ

Z/H

Smooth cement slope PUR-stone made of 16/32 mm limestonePUR-stone made of 8/11 mm limestone Log. (Smooth cement slope)Log. (PUR-stone made of 16/32 mm limestone) Log. (PUR-stone made of 8/11 mm limestone)

γ (OSA, Basalaton)

γ (Rubble mound ofrock)

γ (Grass, colloidalconcrete)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0H/d

γ

PUR-stonemade of16/32 mmlimestonePUR-stonemade of8/11 mmlimestoneγ (OSA,Basalaton)

γ (Rubblemound ofrock)

γ (Grass,colloidalconcrete)

Log. (PUR-stone madeof 8/11 mmlimestone)Log. (PUR-stone madeof 16/32 mmlimestone)


mixed with the abrasive materials in the water; the sur-faces of two specimens were uneven, the stones on top were round and slick; lots of abrasive materials were found in the gaps as well; besides, by the feeling of touch, it was believed there was almost no polyurethane covering around the stones on surface. The deepest holes of the two speci-mens were about -3.5 cm, (‘-‘ means below the surface level of basalt specimens, hereinafter the same), the rest points varied from -0.5 to -2.5 cm, the average surface level was about -1.5 cm.

PUR-stone specimens made of 16/32 mm yellow lime-stone

Some stones were stripped off and mixed with the abrasive materials; the surfaces were quite uneven and the stones on top were round and slick, which is similar to the situ-ations of specimens made of 8/11 mm yellow limestone. Some abrasive stones were found in the gaps; there was almost no polyurethane covering around the top stones. The deepest holes of the two specimens were about -3.5 cm, the rest points varied from 0 to -3 cm, the average surface level was about -2 cm.

Open stone asphalt specimens

Lots of aggregates were stripped off and mixed with the abrasive materials in the water; the surfaces of the speci-mens were considerably uneven, the exposed stones on top were slick and round; there were still a little bit asphalt left but not many abrasive materials were found among the stones due to the big gaps. Two deepest holes of -4.5 cm and -5 cm were observed, even the cement and wood plate at the bottom were exposed and visible. The rest points varied from -4 to -1 cm.

The test results suggested the artificial basalt specimens were strongest. The abraded degrees of PUR-stone speci-mens were between those of colloidal concrete specimen and open stone asphalt specimens (see Fig. 14, 15). The surfaces of all the four PUR-stone specimens were rough and uneven; some stones were stripped off and mixed with the abrasive materials. Many abrasive materials were found

•

•

in the gaps; besides, by the feeling of touch, it was be-lieved there was no polyurethane around the stones on the surface of the specimens. The open stone asphalt speci-mens were abraded most seriously. A lot of asphalt and ag-gregates were moved away and two of the three specimens were considerably damaged; even the white wooden plate at bottom could be observed in one of them. Besides, only a few small abrasive materials were found probably due to the bigger gaps. One of the three OSA specimens had less erosion and more abrasive materials among the gaps. It was probably because it was located between the arti-ficial basalt specimen and the colloidal concrete specimen which were both relatively much stronger than open stone asphalt; so the abrasive action on this OSA specimen was more or less weakened.

One point should be concerned when comparing PUR-stone specimens and open stone asphalt specimens. The PUR-stone specimens were tested directly at about 50 days after the production; but the open stone asphalt specimens were sawed from the samples collected from a dike which was constructed at least 20 years ago which means the proper-ties of the tested OSA specimens were certainly different with the properties of fresh OSA.

The Application of GOLFKLAPAccording to ‘Dutch Guidelines for the Assessment of the Safety of Dikes 2004’, the investigation of asphalt revet-ments in respect of mechanism consists of a comparison between the actual layer thickness and required layer thickness. Two methods have been developed for obtain-ing the required layer thickness (a simplified and a more detailed method); the simplified one is to determine the required thickness from the graph shown in Fig. 16 which was derived by previous computer programs and relative data; the more detailed one is carried out using the com-puter program GOLFKLAP of which the latest version is 1.2. Table 9 shows for what combinations of age and mortar percentage the simplified method is applicable (Step 3) and

Figure 15 Abrasive test results of PUR-stone specimens made of 8/11 mm limestone and 16/32 mm limestone

Negative deviation relative to mortar

content agreed when laying

[percentage by mass]

Age (years)

0 - 5 6 - 10 11 - 15 16 - 20 > 20

0 - 0,5 3 3 3 3 4

0,6 - 1,0 3 3 3 4 4

1,1 - 1,5 3 3 4 4 4

1,6 - 2,0 3 4 4 4 4> 2,0 4 4 4 4 4

Table 9 Applicability’s requirement of aged open stone asphalt

Figure 16 Design graph of asphalt revetment

Figure 14 Abrasive test results of OSA, basalt and PUR-stone discs


for what combinations the detailed method must be applied straightaway (Step 4); in which, the quantity of asphalt mortar used is taken as an indicator of the quality of open stone asphalt, because this determines how thick and du-rably the stones are enclosed.

In this project, fresh OSA and aged OSA were compared to fresh PUR-stone respectively. According to Table 9, step 3 was applied to fresh OSA and step 4 was applied to aged OSA (in operation for more than 20 years) based on the test data provided by Road and Railway Engineering Sec-tion, TU Delft.

Considering the similar structure of PUR-stone and OSA as well as the same structure of PUR-revetment and OSA re-vetment, it was believed to be feasible to apply GOLFKLAP to PUR-revetment; besides, most of the necessary mechan-ical data of PUR-stone for the calculations in GOLFKLAP had already been obtained from the previous four-point bend-ing frequency sweep test and three-point bending strength test. So step 4 was decided to apply to PUR-revetment. Additionally, the calculations of GOLFKLAP needs fatigue line, but at that moment the fatigue property and the fa-tigue line of PUR-stone was still unknown. So in this study, the fatigue line of PUR-stone was assumed based on the fatigue line of aged OSA; and this assumption was believed to be very conservative because from the four-point bend-ing frequency sweep test results it was known already PUR-stone was more or less elastic.

GOLFKLAP is a computer program for the design and evalu-ation of an asphalt revetment at wave impacts. It calculates the bending stress in the revetment due to wave loads and compares it with the failure stress to verify whether the construction will yield. To calculate this bending stress in GOLFKLAP, the revetment is schematized as an elastic beam supported by small springs; so the structure can be characterized by the layer thickness, the stiffness modulus, the fatigue strength of the material and the modulus of subgrade reaction; the wave impacts are schematized as a series of triangular loads on the layer (see Fig. 17).

In this study, the minimum required layer thickness of the

revetment was considered as the parameter for compari-son. The minimum required thickness meant the minimum practical layer thickness or the layer thickness when the value of miner sum, which was the output data of GOLF-KLAP, was equal to 1; because the revetment would prob-ably fail when the value of miner sum was larger than 1.

In Fig. 16, the horizontal axis indicates the significant wave heights, the vertical axis indicates the thickness of OSA layer. Two kinds of sub-layer are available for reference, sand and clay; for each sub-layer, several inclination curves or lines are provided for getting the minimum required layer thickness based on a certain significant wave height. In this study, only one sub-layer (clay) and one inclination (1:3) were applied. The results obtained from Fig. 16 are included in Table 11.

The minimum required thicknesses of PUR-stone and aged OSA were calculated in GOLFKLAP 1.2. The major input parameters are provided in Table 10; in which, the stiffness of aged OSA was obtained from the previous test results carried out in the Road and Railway Engineering lab of TU Delft, ‘a‘ and ‘log(k)‘ are coefficient and intercept of the fatigue curve.

In Table 11, a summary of the minimum required layer thicknesses of fresh PUR-stone, fresh OSA and aged OSA at various wave impacts (significant wave heights) are given. Lower wave heights were neglected in Table 11 because the minimum required layer thickness was determined by the practical value at small wave impacts; in another word, the differences of the results were not obvious for comparisons. In conclusion, it was found that at the same significant wave heights, PUR-stone requires the smallest layer thick-ness compare to fresh OSA and aged OSA.

CONCLUSIONSBased on the results of all the experiments and the calcula-tions in GOLFKLAP, the conclusions of this study are given:

The stiffness of PUR-stone is lower than that of aged OSA at low temperature. It varies with different tem-perature, stone size and quality; the higher the tem-perature is, the lower the stiffness is; but the stiffness of PUR-stone remains almost constant at a certain tem-perature with different frequencies of load.

The strength of PUR-stone is higher than that of open stone asphalt. It is basically constant but sometimes varies due to its particular open structure; furthermore, the strength is not always determined by the bonding force because sometimes the bonding connections can be stronger than the stones themselves.

For PUR-stone specimens produced by stones of 8/11 mm and stones of 16/32 mm, the porosity of them is similar to each other.

PUR-stone stays more stable on the non-woven geo-textile compared with woven geotextile; a short delay between the production and the application makes no influence as long as it is in the range of the required application period. Considering the usual angle of a re-vetment is 1/3 or 1/4, it is feasible to apply PUR-stone to the real construction on site.

For PUR-stone of small thickness, the influences of

•

•

•

•

•

Fresh PUR-stone Aged OSA

Slope inclination 0.33 0.33

Bearing capacity of sub-layer (Mpa/m) 30 (clay) 30 (clay)

Stiffness (Mpa) 3000 4500

Poisson 0.35 0.35

Water depth (m-NAP) 10 10

a 6 6log(k) 3.3 1

Hs Tg Thickness (m)(m) (s) Fresh PUR-stone Fresh OSA Aged OSA

2.5 5.53 0.21 0.36 0.98

3 6.06 0.31 0.54 1.35

3.5 6.55 0.43 0.75 1.774 7 0.56 0.97 2.2

Table 10 Major input parameters in GOLFKLAP

Table 11 Summary of the layer thickness comparison results

Figure 17 Schematization of the revetment in GOLFKLAP


stone sizes and blocking points can both be neglected; however, for PUR- stone of big thickness, these influ-ences should be considered; moreover, the influence of stones sizes is bigger than that of blocking points regarding the porosity of PUR-stone made of 8/11 mm yellow limestone and that of PUR-stone made of 16/32 mm yellow limestone are similar. In another word, for larger thickness, the grading width of stones decides the permeability of the interface between PUR-stone and geotextile despite of the blocking points.

The roughness factor of PUR-stone slope made of 16/32 mm yellow limestone varies from about 0.7 to 0.9; the roughness factor of PUR-stone slope made of 8/11 mm yellow limestone varies from about 0.8 to 0.9. Both of them have smaller roughness factor than grass, col-loidal concrete, basalaton and open stone asphalt; but larger than rubble mound of rock. The different perme-able extents of two different PUR-stone slope probably cause their different roughness factors at impacts of plunging waves.

The artificial basalt blocks are strongest. The resistance of PUR-stone to abrasive action is better than that of open stone asphalt but worse than that of colloidal con-crete.

At same wave loads the required minimum layer thick-ness of PUR-revetment is smaller than that of open stone asphalt revetment.

In conclusion, compared to open stone asphalt (see Table 12), PUR-stone is a kind of strong and permeable material; PUR-revetment is relatively easy to be constructed and maintained as well. It is expected to be a suitable material for applications of revetments.

ACKNOWLEDGEMENTSThe research was supported by Elastogran GmbH, BASF Group. The author wish to thank the fluid mechanics labo-ratory in Delft University of Technology as well as the road and railway engineering laboratory in Delft University of Technology for their assistance throughout the design and operation of all the experiments.

REFERENCESAnongmous. 2004. De Veiligheid van de Primaire Waterkeringen in Ned-

erland, Voorschrift Toetsen op Veiligheid voor Detweede Toetsronde 2001-2006 (VTV). Den Haag: Ministerie van Verkeer en Waterstaat. 303-310.

Anongmous. 2005. Standaard RAW Bepalingen 2005. CROW. 1084 p.De Looff, A., Hart, R., Montauban, K., and Van de Ven, M. GOLFKLAP

a model to determine the impact of waves on dike structures with an asphaltic concrete layer.

Evertz, T. 2007. Elastomeric revetments–a new way of coastline protec-tion. PhD thesis, Hamburger Wasserbauschriften, Technical University of Hamburg-Harburg, Germany. (not published yet)

Gu, D. 2007a. Some important mechanical properties of Elastocoast for safety investigation of dikes (VTV 2004). Minor Msc. thesis, Depart-ment of Civil Engineering, Delft University of Technology, Delft, The Netherlands.

•

•

•

Criterion Type OSA revetment PUR-revetment

Accessibility + +

Construction & maintenance - +

Costs depends depends

Flexibility for subsidence + ?

Heavy loads + ++

Landscape depends depends (+)Space required 0 0

Table 12 Comparisons between OSA revetment and PUR-revetment

Gu, D. 2007b. Hydraulic properties of PUR-revetments compared to those of open stone asphalt revetments. Msc thesis, Department of Civil Engi-neering, Delft University of Technology, Delft, The Netherlands.

K. d’Angremond and F.C. van Roode. 2001. Breakwaters and closure dams. Delft: Delft University Press.

Pilarczyk, K. 1998. Dikes and revetments. Lisse: A.A. Balkema.Pilarczyk, K. Design of revetments.Schiereck, G.J. 2001. Introduction to bed, bank and shore protection. Delft:

Delft University Press.Onderzoek Open Steen Asfalt Havendammen Oosterschelde

FIRST EXPERIENCE WITH POLYURETHANE REINFORCED REVETMENTS IN THE NORTH SEA OF SCHLESWIG-HOLSTEIN (GERMANY)

Dipl.-Ing. Alfred Mordhorst, LKN* Husum, [email protected]

Dipl.-Ing. Peter Beismann, LKN* Husum, [email protected] Dipl.-Ing. Thorsten Evertz, Golder Associates GmbH, [email protected]

INTRODUCTION After profound changes to the coastline, over 100 holms have been created in Schleswig-Holstein in the past centuries. However, only ten of them have survived to the present day. They are protected from further erosion through fixation of their edges. Despite such stabilization measures breaking waves generated by storm surges still cause considerable damage through eroding of the land behind. PU-REVETMENTS AS BREAKWATER A new construction method of so called Polyurethane (PU)-revetments (Evertz, Petersen: 2007) has been tested successfully as stable breakwater constructions on holm “Hamburg Hallig” and “Gröde” evidenced by laser-scanning monitoring by TU Hamburg Harburg (Evertz, Pasche: submission 2008).

Figure 1- “Hamburger Hallig”: laser-scanning monitoring of the PU-revetment by TU Hamburg Harburg (TUHH; Inst. of River and Coastal Eng.)

PU-revetments consist of a 2-component polyurethane (PU) bonding system that reinforces gravel on the surface of their contact points. Only 1,8 ppw of the environmentally neutral PU material creates together with the gravel an open porous, stable three dimensional, monolithic structure. This coastal protection technology is cost-effective due to an easy process and savings in construction materials as the layer of PU-revetments can be designed thinner compared to concrete or bitumen revetments. The wave impact is significantly absorbed by friction in the totally open porous structure of PU-revetments. This causes a reduced wave run up evidenced by wave channel tests at TU Delft (Section of Hydraulic Eng.; Verhagen, Ven, Gu: submission 2008) Successfully realized projects of 5000 sqm show PU-revetments are an economic and technically accepted alternative to conventional revetments.

PU-REVETMENTS IN SCHLESWIG-HOLSTEIN The very first PU-revetment was installed on holm “Hamburger Hallig” as a breakwater construction in 2004 followed on holm “Gröde” with 3500 sqm in 2006 and 2007.

Figure 2- 3500 sqm PUR-revetment on holm “Gröde”

The LKN* made further successful experience with PU-revetments on Sylt island (“Ellenbogen”) installed 2005 in a heavy surging zone, while brittle concrete constructions failed 2008 shortly after six month duration at the same position. Another 1500 sqm revetment was installed at “Sylt-Munkmarsch” at the tidal side of the island.

Figure 3- 1500 sqm PU-revetment on “Sylt-Munkmarsch”

In December 2007 a PU-revetment as function of an embankment protection at the tidal river “Lecker Au” was securely installed where before the embankment was constantly eroded. Further PU-revetment installations in 2008 are ongoing in Schleswig-Holstein. REFERENCES Evertz, Pasche: „Verfestigung von Deckwerken mit PU - Elastomere Deckwerke im Wasserbau“ TUHH (submission in 2008) Evertz, Petersen: Wasser & Abfall; 6/2007;„Neue Wege bei der Verfestigung von Deckwerken“ Verhagen, Ven, Gu: „Preliminary Study of PU-Revetment Application” TU Delft (submission 2008) *LKN: Schleswig-Holstein Agency for Coastal Defense National Park and Marine Conservation