frank-zemdrain-exp

Zemdrain®-Controlled Permeability Formwork (CPF)liners for high quality durable concrete surfaces

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Zemdrain®

Summary of Contents

Properties and actions

Why use? ...............................................................................................................Page 4

Improving the concrete cover zone .........................................................................Page 5

How it works .............................................................................................................Page 6

What it does..............................................................................................................Page 7

Visible Benefits ..........................................................................................................Page 8

Measurable Benefits................................................................................................Page 10

Impact of formwork .................................................................................................Page 12

Impact of cement types ..........................................................................................Page 13

Impact of admixtures & mix strength .......................................................................Page 14

Impact of coatings & penetrants..............................................................................Page 15

Performance with time ............................................................................................Page 16

Performance in extreme / harsh climates.................................................................Page 17

The economic benefits of using...............................................................................Page 18

Practical applications:

Zemdrain® MD or Classic ........................................................................................Page 19

Transport / Marine / Waterway Structures ...............................................................Page 20

Potable Water / Wastewater Structures...................................................................Page 21

Practical applications on formwork..........................................................................Page 22

Tender specification clauses and product range

Specification clauses...............................................................................................Page 24

Zemdrain® MD product range ................................................................................Page 25

Zemdrain® Classic product range............................................................................Page 26

Instructions for use

Technical Guidelines ................................................................................................Page 27

Fixing details - Zemdrain® MD ...............................................................................Page 28

Fixing details - Zemdrain® Classic ...........................................................................Page 29

Frequently Asked Questions....................................................................................Page 30

Reports:

Test certificate / report summary .............................................................................Page 31

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Zemdrain® is DuPont’s registered trademark.www.zemdrain.com

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Zemdrain®

Why use?

Problems that can arise due to the use

of oiled impermeable faced formwork

and to workmanship include:

■ excess air and water trapped at the

formwork/concrete interface

■ reduced cement contents

■ surface contamination

■ improper/ ineffective curing

■ insufficient cover

Air(2) trapped at the surface results

in blowholes and pinholes. Although

attempts are made to fill these in, over

the longer term they reappear and look

unsightly.

Water(2) trapped at the surface can

cause other blemishes:

■ a weak surface laitence

■ segregation

■ scouring

■ bleeding

■ some forms of cracking

Water gain(1) in the outer 20 mm of

the surface leads to an increase in

w/c ratio and a decrease in cement

content.

Decreases in cement content of up

to 40 kg/m3 have been measured,

irrespective of mix strength, cement

type, admixture use or formwork orien-

tation.

The resulting surface has higher porosi-

ty and is more liable to degradation

from abrasion, acid attack and other

aggressive elements

Release Agents(3) prevent full hydra-

tion of the surface concrete, with

dusting a sign of incomplete hydration.

Residues of biological release agents

contaminate the concrete surface and

encourage bacterial growth in all

wet/dry environments.

The performance of coatings and pe-

netrants can also be reduced by these

residues.

Curing(4) is beneficial in improving the

performance of the cover zone concre-

te to a depth of 20 to 50 mm.

Properties imporved by curing:

■ resistance to dusting

■ resistance to abrasion

■ risk of cracking reduced

■ reduced surface porosity

Curing is rarely carried out correctly. It

is often not applied early enough and

for too short a period.

Higher surface porosity due to the

water gain from the use of oiled imper-

meable faced formwork causes an

immediate loss of moisture on form-

work removal. The result is reduced

concrete performance.

Insufficient Cover(5)

Several extensive surveys have shown

that deficiencies in cover of over 15 mm

are common. The need for high quality

surfaces is therefore very important.

The reality is that the outer 20 mm of

the concrete surface is the poorest in

the structure. The combination of redu-

ced cover and poor quality concrete

ensure a reduced structural life in any

aggressive environment.

The outer surface (up to 20 mm)

is usually the poorest quality

concrete in the structure due to

“process“ problems(1).

The Solution: The use of Zem-

drain® CPF liners to overcome the

majority of “process“ problems.

Zemdrain®

Improving the concrete cover zone

5

Zemdrain® use results in improved

quality and durability of the cover

zone concrete(16).

By replacing oiled plywood and steel as

the formwork face contact material,

Zemdrain® overcomes many “process“

problems by:

■ removing excess air

■ removing excess water

■ not using release agents

■ acting as a curing membrane

The resulting concrete surface is of

higher quality and more resistant to all

aggressive elements such as chloride

salts, carbon dioxide acidic water and

freeze/thaw action.

Laboratory and in-situ testing has

shown Zemdrain® to be effective with

all concrete grades, cement types, ad-

mixture types and to work irrespective

of formwork orientation and height of

pour. Zemdrain® use in hot climates is

also very beneficial, particularly the

curing benefits(7).

Zemdrain® formwork liners provide a

simple and effective method of produ-

cing a virtually blemish free, dense,

low permeability cover zone. The result

is increased protection of the steel

reinforcement and the concrete core

from attack by aggressive elements.

Recent research(8) has concluded that

if a CPF liner is used correctly, the

resulting durability benefits can be

equivalent to having an extra 15 mm to

20 mm of cover.

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■ surfaces free of blowholes and

other blemishes

■ increases in cement content

of up to 100 kg/m3 in the outer

20 mm of the surface

■ decreases in w/c ratio

■ surfaces that are hostile to

growth of microorganisms

■ durability benefits equivalent

to an extra 15 - 20 mm of cover

■ a well cured surface

■ release agents are not used

■ minimal formwork cleaning costs

■ liner can remain on concrete

surface to protect from dirt and

damage

■ longer service life of highly-

loaded concrete structures

■ significant reduction in upkeep

costs for structures

■ provides an ideal surface for coatings without the need for preparatory work

■ reduction in costs which arisedue to operational downtimecaused by refurbishment ofstructures

■ improvement in concrete appearance

■ the use of less expensive concrete mixes is feasible

Concrete formed with Zemdrain® offers the following benefits:

The result is a virtually blowhole-

free, low porosity, uncontaminated,

high quality concrete surface which

is highly resistant to aggressive

environmental agents

Using conventional formwork Using Zemdrain®

Zemdrain®

How it works

Zemdrain® acts as the formwork face

contact material(9). Both sides of the

formwork liner are different and have

unique functions.

The formwork side has a drainage/

storage function. It ensures that air and

excess water are collected at the

contact surface with the formwork and

are removed using a textured surface

with coarse fibres or a grid.

The concrete side, with its controlled

pore structure, retains the cement

fines, which leads to a denser and

less porous surface. Zemdrain® only

permits removal of excess quantities of

water and air, and there is no vacuum

effect. Water removal is by gravity,

ensuring an ideal w/c ratio in the outer

20 mm of the cover zone. This encour-

ages quicker and more complete

hydration of the cement with reduced

pore formation. The resulting higher

concentration of fine constituents and

cement reduce surface porosity and

the formation of blowholes.

The result is a denser, more compact

and more durable concrete cover zone,

which protects the concrete core

and the reinforcement from attack by

aggressive elements.

Concrete

VibratorFormwork Panel

Zemdrain®

Enlargement of the filter layer which

retains the cement particles.

Conventional formwork

Air and excess water in the concrete

are expelled to the formwork surface

by vibration energy. The result is

blowholes, other surface blemishes,

an increased w/c ratio and decreased

cement content in the concrete cover

zone. It is easier and quicker for harm-

ful substances to penetrate this more

porous concrete. Aggressive agents

can begin their destructive work earlier

and more intensively.

Formwork with Zemdrain®

Zemdrain® CPF liners remove excess

water and air from the concrete sur-

face in a controlled manner. Cement

fines are retained at the surface. The

result: an almost blemish free and low

porosity surface with significantly redu-

ced w/c ratio and increased cement

content. The dense, hard, low perme-

ability concrete in the outer cover zone

gives improved protection to the rein-

forcement.

Form

wo

rk f

ace

With

Zemdrain

® - decreasing w/c ratioZemdrain®

Formwork with Zemdrain®

H2O: excess water taken up

H2O: water required for hydration given back

0.7

0.5

Formwork without Zemdrain®

Without Zemdrain ®

- increasing w/c ratio

w/c = 0.4

w/c = 0.5

w/c ratio

Concrete Cover

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Zemdrain®

What it does

The fine pore structure of the Zemdrain®

filter facilitates removal of excess water

from the surface zone during and after

vibration. The quantity of water removed

will be a function of initial w/c ratio, any

admixtures used, type of cement and

vibration efficiency. Tests carried out

worldwide confirm this conclusion.

Water removal and the water/

cement ratio

Reductions in w/c ratio of 0.05 to 0.25

are common with between 0.3 and

2.0 litres/m2 of water drained off. The

greater the initial w/c ratio of the mix,

the greater will be the quantity of water

removed.

Absorbency and Drainage

Too much absorbency and too little

drainage capacity can reduce the effec-

tiveness of a formwork system:

■ absorbent timber can remove only

0.2 litres/m2 of water on first use.

Further uses cause pores to block,

reducing drainage. This type of tim-

ber is not effective in this application.

■ thick fleece liners absorb around

0.8 litres/m2 of water. Such a small

amount of water can already be

absorbed by a fleece liner prior to

concreting due to for example light

rainfall.

■ Zemdrain® liners have low absorb-

ency, relying upon vibration and con-

crete head to force out excess water.

Classic requires positive drainage,

while MD has enough capacity

(1.5 litres/m2) to function without

drainage for most mixes.

Does the weather influence

Zemdrain® performance?

Higher cement concentrations on

the surface

Removal of the excess water leads to a

flow of cement particles which concen-

trate in the surface zone, thus forming

a dense and compact concrete cover

with a high pH-value.

Mass ratios

Denser concrete boundary zones

The ideal ratio of water to cement en-

courages quicker and more complete

cement hydration. As there is minimal

excess water available, there are few

pores remaining after evaporation. The

result is a high concentration of fine

constituents and cement and thus a re-

duction of porosity.

Petrographical images

In contrast to absorbent timberand thick fleeces, the weatherhas no influence on the wayZemdrain® performs, which al-ways remains the same.

Any water resulting from rainshowers immediately beforeconcreting is not absorbed by Zemdrain®, so that its fullwater-draining capacity is stillavailable for the excess waterin the concrete.

Water will only pass throughZemdrain® under the influenceof concrete pressure and vibra-tion.

1

0.1

Distance from surface (cm) With Zemdrain® Without Zemdrain®

TU Munich tests Mass ratios in 12 cm test wallwith/without Zemdrain®

w/c value

cement/sand

2 3 4 5 6 7 8 9 10 11 12

0.2

0.3

0.4

0.5

0.6

Without Zemdrain® porous texture

With Zemdrain® denser structure Excess water drained out by Zemdrain® is evacuated to the outside via the formwork.

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Freeze / Thaw Resistance(10) The problem: Expansion of capillariescaused by ice pressure, also under theinfluence of de-icing substances, leadsto spalling of the concrete surface. The porous surface, which results fromthe use of traditional formwork facecontact materials, can readily displayspalling after relatively few freeze/thawcycles.

Zemdrain®

Visible benefits

Surface Hardness(3,8) The problem: Vibration moves air andwater to the formwork face. The resul-ting concrete surface is weak andporous. Such concrete surfaces are liable todegradation from abrasive action. Theyalso require costly preparatory work prior to coating application.

Benefits of Zemdrain®

By removing the excess air andwater, an optimum w/c ratio isachieved in the cover zone. Com-plete hydration of the cement re-sults in a surface with increasedhardness and tensile strength.The dense, blemish free surfaceprovides an ideal base for coa-tings without extensive substratepreparation.

Carbonation(3,8,13,20) The problem: Carbonation reducesthe alkalinity of the concrete, removingthe protection to the steel. Carbonatedconcrete encourages quicker pollutantentry and results in reduced concretedurability.The rate of absorption of carbon dioxi-de and other harmful gaseous sub-stances from the atmosphere is signifi-cantly increased by the porous surface

formed by oiled steel or plywood facedformwork.


Significant reduction in the rate ofcarbonation due to a dense coverzone - resulting from increases in cement content of up to 100kg/m3 in the outer 20 mm of thesurface.

Water / Chloride Ingress(3,8,13,20,25)

The problem: Most coastal and trans-port structures are subject to wettingand drying cycles in the presence ofwater borne chlorides.The quality and permeability of the sur-face concrete governs surface chloridelevels and chloride diffusion rates. Thesurfaces produced by conventionalformwork increase the rates of chlorideingress and water penetration.


Zemdrain® improves the frost resistance of concrete with or without air entrainment due to re-duced surface porosity. The improved weathering re-sistance of the surface leads toincreased durability for transportstructures subjected to de-icingsubstances.

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Reduced w/c ratio and higher ce-ment contents at the surfacecombined with better curing leadto a concrete cover zone with lower porosity and permeability.Resistance to water borne ag-gressive agents such as chloridesis increased.

WithZemdrain®

WithoutZemdrain®

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Zemdrain®

Visible benefits

Microbiological Growth(1,3,11) The problem: Micro-organisms canreproduce and live in blowholes, largecapillary pores and imperfections in thecarbonated outer concrete surface. Modern biologically degradable releaseagents, residues of which can penetra-te up to 5 mm into the surface, providenutrients for further organic growth. Potable water reservoirs made of un-treated concrete, with the use of relea-se agents pose a danger for hygienicand problem free drinking water.


The uncontaminated, virtuallyblemish free surface with its in-creased hardness and resistanceto carbonation provides a hostileenvironment resistant to micro-organism growth.

Acid / Chemical Attack(26,27) The problem: The acid resistance ofconcrete depends upon the cementcontent and porosity of the surface.The greater the cement content thelonger the surface will resist degrada-tion.Surfaces produced by oiled impermea-ble formwork have significantly redu-ced cement contents and increasedporosity.


Zemdrain® use results in an in-crease in surface cement contentof up to 100 kg/m3 and reduc-tions in surface porosity of around30 %. The result is a surface with signifi-cantly increased resistance toacid/chemical attack.

Curing Effect(1,4,20) The problem: Water gain in the outercover zone results in a porous surface,which on formwork removal allows arapid escape of moisture into the at-mosphere. This has a negative influen-ce on the hydration process. Unless curing is applied immediatelyand is maintained, the result can besignificant reductions in concrete quali-ty and a rapid drying out of the surface.


Zemdrain® retains drainage waterin its structure and acts as a cu-ring membrane until the formworkis removed.Lower porosity in the cover zoneminimises moisture loss.Zemdrain® use largely desensi-tises concrete to the effects of poor quality curing.

Surface Blemishes(12) The problem: Water and air trappedby the use of oiled steel and plywoodfaced formwork cause blowholes andother blemishes. These blemishes arenot only an aesthetic problem, but alsoreduce long term durability. Repairs areusually cosmetic and have a short life. Many more blowholes are present justbeneath the surface and are easily re-vealed by grit blasting.


Water and air removal results in avirtually blemish free surface forboth inclined and vertical surfa-ces. Sandblasting exposes fewfurther blowholes.

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Zemdrain®

Measurable benefits

Important concrete properties are measurably improved by using Zemdrain® in differing con-crete compositions.

0

0.5

1.0

1.5

2.0

2.5

MPa

100% PC CEM I

Definition to EN

70% PC/30% PFA CEM II/B-V

0.59

2.1

0.76

2.35

0.59

1.56

0.87

2.17

50% PC/50% GGBSCEM III/A

0.87 0.87

2.13

2.32

30% PC/70% GGBSCEM III/B

0.55

2.13

0.72

2.34

100% PC-AEA CEM I + AEA

0.52

0.98

2.13

With curing

Without curing

With curing

Without curing

With curing

Without curing

With curing

Without curing

With curing

Without curing

2.32

Without Zemdrain®

With Zemdrain®

1. Surface strengthMeasured according to BS

1881 (pull-out test at 28 days)

Up to five times stronger surfa-

ce strength has been achieved

through the use of Zemdrain®,

thanks to optimum cement

hydration.

0

1000

2000

3000

4000

ml/m

2061

306

1103

113 126

779

81

2493

194

2106

279

3618

518

18721872

180

806

86

540

54

2

100% PC CEM I

Definition to EN





With curing

Without curing

With curing

Without curing

With curing

Without curing

With curing

Without curing

With curing

Without curing

2. Surface absorptionTwo hours cumulative Initial

Surface Absorption Test (ISAT)

according to BS 1881, after 28

days.

Surface of the concrete is up

to ten times less permeable

due to a denser structure and

fewer capillaries left by evapo-

ration of excess water.

0

2

4

6

8

10

12

mm

7

1

9

0.5

10

1.5

8

0.5

8.5

3

9

0.5

12

2

9

0.5

5

0.5

3

0.5

Without Zemdrain®

With Zemdrain®

100% PC CEM I

Definition to EN





With curing

Without curing

With curing

Without curing

With curing

Without curing

With curing

Without curing

With curing

Without curing

3. CarbonationAccelerated test, for 12 weeks,

4% CO2, 50% RH, 23°C, at 28

days age

Up to ten times greater resi-

stance to carbonation has be-

en measured at the surface, as

a result of the reduced porosity

of the concrete cover.

The surface of a C20 concrete

cast against Zemdrain® form-

work liner is more durable than

that of a conventionally cast

C50 concrete.

With Zemdrain®

WithoutZemdrain®

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Zemdrain®

Measurable benefits

4. Chloride diffusionAccelerated test, extrapolated

according to the Second Law

of Fick (at 28 days): AASHTO T

227-831

When Zemdrain® is used, the

time necessary to activate cor-

rosion of steel reinforcement

by reaching a specified con-

centration of chloride (0.4 %

Cl / cement) is two to ten times

longer.

No. of cycles

1

0

2

3

4

5

6

Scaled Material, kg/m2

no cure

7 14

with cure no cure with cure no cure with cure no cure with cure no cure with cure

28 42 56

Without Zemdrain®

With Zemdrain®

5. Frost resistanceAccording to Swedish SS 137

244: freeze / thaw cycles with

solution of sodium chloride

Thanks to a denser, less

porous cover, up to one hun-

dred times less material scaling

has been measured on surfa-

ces cast with Zemdrain®.

NB: done on a different mix:

C65; w/c = 0,42; AEA 2,2%,

M 5%

50

0

100

150

200

Effect (%) relative to control sample without Zemdrain®

and without curing

2 hours cumulative ISAT

38

100

5

50

Surface hardness

100100

136

117

Accelerated carbonation

9596

10

38

hot-dry

Chloride diffusion

95

163

18

57

hot-wethot-dry hot-wethot-dry hot-wethot-dry hot-wet

With Zemdrain®, without curingWithout Zemdrain®, 3 days curing

6. Curing effectAll properties of a concrete

surface cast against Zemdrain®

formwork liner, and left without

cure in the lab, are better than

those obtained on a surface

cast again conventional forms

followed by an ideal wet cure.

High surface porosity explains the poor

performance of the control mixes with

GGBS, compared with results of tests on

cubes and cylinders. The use of Zemdrain®

enabled concrete to achive outstanding

resistance to chloride diffusion in all mixes.

0

100

200

300

400

Years

3467

3565

40

97

35

147

33

217

27

361

40

345

60

353

85

191

77

210

Without Zemdrain®

With Zemdrain®

100% PC CEM I

Definition to EN




no cure


wet cureno cure wet cureno cure wet cureno cure wet cureno cure wet cure

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Zemdrain®

Impact of Formwork

The types of formwork face contact

material used will vary between sites

and countries. The most commonly

used facing materials are oiled

plywood, timber and steel.

The orientation of the formwork de-

pends upon the application and can

be vertical, inclined top, inclined bot-

tom, soffit and top horizontal.

The types of face contact materials

and release agents used, and the qua-

lity of workmanship can cause:

■ surface blemishes due to trapped air

and water

■ surface contamination due to the

use of release agents

■ increased w/c ratio and decreased

cement content in the outer 20 mm

of the surface

These problems can be magnified by

the use inclined shutters. Trapped air

shows up as blowholes and pinholes.

Their size and frequency increasing as

the inclination of a top shutter gets

shallower. On any formed surface, a

light grit blasting will reveal many more

blemishes.

Zemdrain® can be used with all form-

work types. Irrespective of the backing

material and formwork inclination,

Zemdrain® use will normally result in:

■ a virtually blemish free surface

■ a surface uncontaminated by relea-

se agent residues

■ improved early age curing

■ decreased w/c ratio and increased

cement content in the outer 20 mm

of the surface

Any Zemdrain® cast surface will after

light grit blasting reveal significantly

less blowholes than a non CPF cast

surface.

For top horizontal surfaces Zemdrain®

will only work to remove air and water

if there is sufficient pressure from head

of concrete and vibration to do so.

Panel formwork systems can give un-

sightly joints unless they are overshee-

ted with plywood. Zemdrain® can re-

place this plywood layer to save weight

and to improve concrete quality and

durability.

0

50

100

-50

VerticalSloping

(T)Sloping

(B)

Cement Content

Variation (kg/cu.m)

-40

61

Control

CPF

-44

54

-24

69

Soffit

-30

60It is recommended that trial panels be cast to con-firm performance for any site.

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As-Struck Surface

Grit blasted SurfaceCement Contents in outer 20 mm of Surface(8)

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Zemdrain®

Impact of Cement Types

Different cement types and additions

like Pulverised Fly Ash (PFA), Ground

Granulated Blast Furnace Slag (GGBS),

Meta Kaolin (MK), Condensed Silica

Fume (CSF), can help to improve over-

all concrete durability. This is particu-

larly the case in terms of resistance

to chloride ingress. However, blended

cement concrete can:

■ be more prone to carbonation

■ have an initial surface strength gain

that is generally less than that for a

PC concrete.

■ be more sensitive to the quality of

site curing

Research(8) has shown that when cast

against formwork using oiled plywood

or steel as the face contact material,

the cement content in the outer 20 mm

of the surface can be reduced by up to

40 kg/m3. This occurs irrespective of

the type of blended cement used.

When Zemdrain® is used as the form-

work face contact material with blen-

ded cements, the following is noted:

■ cement contents in the outer 20 mm

of the cover zone can be increased

by up to 100 kg/m3

■ w/c ratio is reduced

■ early age surface hardness and ten-

sile strength are increased signifi-

cantly

■ early age and longer term carbonati-

on are minimised

■ a better cured surface results

■ surface porosity is reduced

Zemdrain® and Blended Cements

The synergism between Zemdrain®

and blended cements enhances the

durability of concrete(13).

The benefits in the outer 20 mm from

using Zemdrain® and the improve-

ments to the mass of the concrete

from the blended cements ensure a

longer structural life.

Improved curing is a major benefit

when using Zemdrain® with blended

cements. Keeping the liner in contact

with the concrete surface for prolon-

ged periods and ensuring that the net

(MD) remains filled with water can en-

hance this effect further.

Zemdrain® and White / Pigmented

Cements

Interest in white and pigmented con-

cretes increases as dissatisfaction

grows with shades of grey concrete

and the pseudo white colour given

by release agent retardation of the sur-

face.

Zemdrain® has been used with diffe-

rent pigments and with white cement

on several projects. The following is

noted or recommended:

■ the pigmented colours will be slightly

darker for Zemdrain® cast surfaces

■ trials should be performed to ensure

that pigments perform correctly with

Zemdrain®

■ with white cement there is a slight

reduction in the whiteness factor

and care should also be taken to

choose light coloured fine aggre-

gate(14).

It is recommended that trial panels be cast to con-firm performance for any site.

Cement Contents in outer 20 mm of Surface(8)

-50

-100

0

50

100

PC PFA GGBS

Cement Content

Variation (kg/cu.m)

-45

55

Control

CPF

-30

45

-60

65

MK

-35

40

CSF

-60

45

Bridge cast using Zemdrain® and white cement

14

Zemdrain®

Impact of Admixtures & Mix Characteristics

Admixtures:

A range of admixtures have been de-

veloped to improve concrete durability,

including:

■ water reducers (WR)

■ superplasticisers (SP)

■ waterproofers (WP)

■ pore blockers (PB)

■ air entrainment (AE)

■ fibres

These improve overall concrete quality.

However, for the outer 20 mm of the

surface, workmanship and the type of

formwork face contact material used

can negatively affect concrete perfor-

mance.

Research(8) has shown that in this criti-

cal zone the use of oiled plywood or

steel as the face contact material can

cause reductions in cement content of

up to 40 kg/m3 and increases in w/c

ratio. As a result of this and the other

“process“ problems, the full benefits of

admixtures are never realised.

When Zemdrain® is used as the form-

work face contact material with admix-

tures, the following is noted:

■ cement contents in the outer 20 mm

are increased by up to 100 kg/m3

over those for the oiled plywood /

steel face

■ w/c ratio is reduced by 0.2

■ increased early age surface

hardness and tensile strength

■ increased resistance to all aggressive

agents

■ surface is better cured

■ surface porosity is reduced

Air entrainment is widely used to im-

prove the frost resistance of concrete.

Results of research have shown that:

■ Zemdrain® modifies the air void sy-

stem close to the formed surface.

The total amount of air entrained in

the cement paste is increased, but

both the spacing factor and specific

surface measurements remain within

accepted guidelines(10)

■ the frost resistance of concrete with

and without air entrainment is impro-

ved by using Zemdrain®.

■ for freezing/thawing In the presence

of deicing salts, Zemdrain® and non

air entrained concrete perform better

than conventionally cast air entrained

concrete

Mix strength:

Increased mix strength is often viewed

as a way of improving durability. But

the use of higher strength mixes can

increase the likelihood of surface ble-

mishes and other process problems.

The surface problems of air and

water gain are also evident for all mix

strengths. The result will be decreased

durability performance. The need for

better curing is also apparent with

increasing mix strength.

The improvements resulting from Zem-

drain® use, also apply irrespective of

mix strength.

Zemdrain® - Admixtures & Strength:

The synergism between Zemdrain®

and admixtures enhances the durabili-

ty performance of concrete.

The benefits in the outer 20 mm from

using Zemdrain® and the improvements

to the mass of the concrete from the

admixtures and/or higher strength

concrete ensure a longer structural life.

Zemdrain® ensures that the maximum

performance benefits are derived from

the use of admixtures and higher

strength (lower w/c ratio) concretes.


Cement Contents in outer 20 mm of Surface(8) Cement Contents in outer 20 mm of Surface(8)

-100

0

50

100

-50

C25 C37 C45

Cement Content

Variation (kg/cu.m)

-20

75

Control

CPF

-45

55

-70

45

-40

-20

-60

0

40

80

20

60

100

PC WR SP

Cement Content

Variation (kg/cu.m)

-45

55

Control

CPF

-45

65

-45

70

AE

-38

88

WP

-40

50

15

Zemdrain®

Impact of Coatings & Penetrants

Coatings and surface penetrants are

usually applied to concrete to protect

the surface from the harmful effects of

the environment. Coatings for architec-

tural reasons are also becoming com-

mon.

Problems affecting coatings and

Penetrants

■ contamination of the surface from

release agents, curing agents, spil-

led oils etc., will inhibit absorption of

penetrants and adhesion of coatings

■ physical defects such as cracks,

blowholes, laitence and general

roughness can effect coating perfor-

mance

■ life expectancy of a coating will be

influenced by the quality of surface

preparation. The majority of coatings

fail due to substrate problems

■ environmental degradation of con-

crete surfaces can reduce effec-

tiveness of penetrants like silane as

they sometimes penetrate only 1

mm into the surface

■ the need for specialist applicators to

apply coatings and penetrants

■ for penetrants like silane the need

for strict Health & Safety precautions

to protect the public and the envi-

ronment. This is particularly the case

for watercourses

■ a life expectancy shorter than that of

the structure they protect, so the

need for several reapplications du-

ring the life of a structure

Benefits of using Zemdrain®

■ surface has a tensile strength of over

1.5 N/mm2

■ surface is uncontaminated by relea-

se agent residues

■ surface is virtually blemish free

■ surface porosity reduced by up to

35%

■ depth of effect is up to 20/30 mm

and lasts the life of the concrete

■ surface is well cured

■ grit blasting of the surface is not nor-

mally needed

■ increased cement content and redu-

ced permeability give a surface that

is more resistant to graffiti and from

attack by acids, chlorides, abrasives

and other environmental agents

■ with Zemdrain® you can see that it

has been used, this is not the case

with the majority of penetrants

Zemdrain® & Coatings

■ the improved quality of the concrete

may mean that a coating is not re-

quired

■ if coatings are required the only pre-

paratory work prior to primer appli-

cation will generally be a surface

cleaning

■ the avoidance of grit blasting and fa-

ring coats can ensure considerable

savings

■ unlike coatings the improvements to

the concrete from using Zemdrain®

have a long life

■ it is always advisable to perform a

trial to confirm that the coating has

good adherence to the Zemdrain®

cast surface

■ putting a coating onto a Zemdrain®

cast surface will enhance the projec-

ted coating life

Zemdrain® & Penetrants

■ the quality of concrete may mean

that use of a penetrant is not neces-

sary

■ laboratory and field results show

that a Zemdrain® cast surface has

lower absorption rates than a control

surface with silane(16)

■ with the absence of release agent

residues and the low porosity of a

Zemdrain® surface, the effectiveness

of silane is improved


Lab Field Lab/Silane Field/Silane

1

0

2

3

4

5

6

7

So

rpti

vity

Ind

ex

Control

Zemdrain®

M2 Bridge, Belfast - Surface Absorption

16

Zemdrain®

Performance with time

The performance of concrete with timeis very important. The actions of aggres-sive environmental agents will causesurface deterioration and eventuallyreinforcement corrosion. Extensive laboratory and in-situ testing of newstructures has shown the significantbenefits to concrete of using Zemdrain®.

Recent in-situ tests on 6 to 7 year oldstructures have confirmed that the be-nefits predicted by laboratory tests areachieved in concrete exposed to de-icing salts and in a marine environment.

The extension to Dock Street bridge inBelfast, N.Ireland was constructed in1992. Testing was performed at the endof construction and repeated in 1999(17).

At the end of construction, test resultsshowed significant reductions in air

permeability and sorptivity and increa-ses in surface strength. The level of im-provements was not affected by silaneapplication.

“The test report concluded that after 7 years in service, that the durabilityproperties of concrete cast againstZemdrain® remain considerably betterthan those of the concrete cast againstnormal formwork.“

Concrete Average Average Air Average CarbonationSurface Surface Permeability Sorptivity (mm)(1999) Strength Index Index

(MPa)

Control 7.28 0.0717 0.499 5 - 10

Zemdrain® 9.21 0.00229 0.073 0

Improvement1.27 1/31 1/7 Very good

Ratio

At Brighton, England, several kilome-tres of sea wall were constructed inthree sections between 1992 and1996. Zemdrain® was used on the sea ward facing faces of the verticaland wave-return sections of the wall(18).

In this very aggressive environment theconcrete used was C45, 70% PC / 30%GGBS with polypropylene fibres. After6 years exposure to the aggressive en-vironment of the Channel, the Univer-sity of Dundee carried out a program-me of in-situ and laboratory testing.

The concrete facing the walkway wascast without Zemdrain® and the growthof algae on this face is very prominent.

Test results have shown the significantbenefits derived from the use of Zem-drain®.

IMF (Steel Faced Formwork) Zemdrain®

Test method (3 yrs. Exposure) (6 yrs. Exposure)

Inter Tidal Splash Zone Inter Tidal Splash Zone

Surface Hardness42 41.6 52.0 55.3

(rebound number)

Pull Off Tensile0.8 1.0 2.4 2.2

Strength (N/mm2)

Capillary Porosity4.865 5.958 3.203 3.391

( % )

ISAT – 1046.1 36.4 16.1 11.4

(m2/sec x 10-2)

Surface Chlorides7.7 10.4 2.3 3.3

(% weight of cement)

Apparent Chloride12.0 27.9 8.1 9.2

diffusion coefficient

17

Zemdrain®

Performance in extreme / harsh climates(19,20,21,28)

Climate extremes, hot or cold and wet

or dry conditions, pose a significant

threat to the life expectancy of con-

crete.

Reinforced concrete structures in hot

climates often deteriorate much more

rapidly than structures in more tempe-

rate regions. Whilst in some cases, this

accelerated deterioration is a result of

unavoidable use of poor quality or con-

taminated materials, the climate itself is

a significant factor.

High initial concrete temperatures lead

to rapid cement hydration, producing

a weak porous microstructure of re-

duced strength and increased perme-

ability. The difficulty of achieving effec-

tive site curing in hot climates is also

well known, with the initial rapid mois-

ture loss after formwork removal par-

ticularly detrimental to long term dura-

bility.

Careful specification of the mix can

enhance the bulk properties of the con-

crete. However, the performance of

the cover zone is significantly effected

by “process“. “Process“ factors include

the type of formwork face contact

material, quality of curing and general

workmanship.

The cover zone is even more important

to long term durability in extreme/harsh

climates.

The use of Zemdrain® has already been

shown to enhance the surface proper-

ties of concrete.

Laboratory and field tests have shown

that Zemdrain® consistently improves

concrete durability in hot/wet, hot/dry

and cold conditions. Perhaps the most

significant finding was that using Zem-

drain® desensitises the concrete against

the effects of inadequate curing.

In hot/wet and hot/dry climates the in-

creased presence of chlorides in the

atmosphere is particularly harmful to

concrete. The effective chloride diffu-

sion coefficient of concrete cast against

Zemdrain® is generally reduced by

more than 50%.

Results for blocks of 50% PC / 50%

GGBS (0.4 w/c ratio) concrete exposed

in the United Arab Emirates are shown.

Levels of surface chlorides and ingress

rates are significantly reduced. The

result is an improved service life for all

reinforced concrete structures.

The use of Zemdrain® prevents sig-

nificant carbonation, and thus allows

chloride binding by the uncarbonated

surface concrete. This will consequent-

ly reduce the risk of reinforcement

corrosion in structures exposed to salt

spray or marine splash zone conditions

in hot climates. This is particularly im-

portant in hot/dry climates.

In extremely cold climates the quality

of the cover zone remains important,

especially when de-icing agents are

being applied.

Zemdrain® use in all extreme/harsh

environments is essential for an

increased structural life.

5 17.5 37.5 62.5 87.5

0.5

0

1

1.5

2

2.5

3

3.5

CI (

% o

f cem

ent c

onte

nt)

Sample Depth (mm)

Control Zemdrain®

Jebel Ali Port Quay 10

0

2

4

6

8

10

12

14

16

Control Zemdrain®

No Cure Cure

HOT / DRY

Car

bona

tion,

mm

Zemdrain®

The economic benefits

Investment decisions

When making investment decisions ab-

out the need to construct structures

such as bridges, drinking water reser-

voirs, sewage treatment works etc., it is

critical to take account of not only the

investment costs, but also the opera-

ting costs.

Maintenance bills are often a major pro-

portion of the operational budget.

Costs associated with minor mainten-

ance work are usually included in the

annual running costs. However, major

refurbishment projects which increase

asset valuations and prolong service life

are handled separately and, in the case

of e.g. sewage treatment works, must

be capitalized.

Initial and ongoing costs

According to current findings - practical

experience since 1989 and test investi-

gations - the time between construc-

tion of a given concrete structure and

its first renovation doubles under the

same exposure conditions if the con-

crete surface has been formed with

Zemdrain®.

The values mentioned therein apply for

a well-organised construction site and

a working team experienced in fixing

Zemdrain® on the formwork.

Costs become charges

In the case of public structures for drin-

king water supply or sewage treatment,

major renovations are often financed

via charges, connection fees or additio-

nal one - off premiums - or even finan-

ced in advance from reserves. The mo-

re expensive and more often that refur-

bishment is required, the higher the

costs which have to be passed on to

the customer. This is often the cause of

intense public discussions.

Construct economically

When talking about cost reduction, we

generally mean investment costs. This

way of looking at things is, however,

rather short-sighted.

Zemdrain® Classic and MD liners

give significant benefits at relati-

vely low costs.

The extra costs to double the

time to renovations are consider-

ably less than the cost of remedi-

als.

The crucial factor is not the in-

vestment costs but the whole life

costs, which result from the in-

vestment costs and the operatio-

nal costs over the service life of a

structure. Here the refurbishment

costs of any structure are of ma-

jor significance.

The use of Zemdrain® helps to

minimise future refurbishment

costs.

Economic benefits of concrete

formed with Zemdrain®

The technical benefits give increased

structural durability. The result is a lon-

ger service life with increased intervals

between any necessary maintenance.

Over the entire service life of any

structure, increased economic be-

nefits result from the use of Zem-

drain® (taking into account a finan-

cial calculation for advance finance

of extra costs).

This was confirmed by a study carried

out by Prof. Seyfried at the University of

Hanover in accordance with LAWA gui-

delines. The adjacent simplified graphic

shows the results(22).

18

3/m2

Years10 30 3520

Extra investmentwith Zemdrain®

15,35 3/m2 Construction investmentwithout Zemdrain®

{

2nd renovation

3rd renovation237,25 3/m2

1st renovation1st renovation

Construction investmentwith Zemdrain®

127,30 3/m2

109,95 3/m2

savings

{

2nd renovation

Costs of 1 m2 concrete surface in sewagetreatment woks during 35-year operationallife including construction and renovationto "basic standard"

19

Zemdrain® MD or Zemdrain® Classic

There are two different styles of Zemdrain®. The differences between them are:

a) Zemdrain® MD (Type III CPF liner*):

■ a composite filter/net liner

■ 2.2 mm thick

■ formwork side - a special drainage grid

■ concrete side - a white engineered filter

■ one roll size at 2.5 m wide and 35 m long

b) Zemdrain® Classic (Type II CPF liner*):

■ a single layer combined filter/drain

■ 0.7 mm thick

■ formwork side - black

■ concrete side - a grey engineered filter

■ various roll widths between 1.6 m and 5.2 m,

standard roll length 50 m

When should you use Zemdrain® MD?

■ for multiple use with minimal risk of folding

■ for reduced costs per m2 of concrete surface

■ for easy application with simple tensioning devices

■ for applications with special formwork or in precast plants

■ for completely sealed formwork - intermediate grid space

serves as additional storage

■ easier to use with circular, concave, convex and complica-

ted formwork shapes

When should you use Zemdrain® Classic?

■ if only one use is necessary

■ when round steel formwork is used in monolithic con-

struction

■ if specifications demand that concrete is cured with Zem-

drain® formwork liner remaining on the concrete face

■ if steel formwork is used which may require wide sheets

■ for applications with special formwork or in precast plants

■ for soffit formwork for bridges

Both types of Zemdrain® produce concrete of equal

quality and durability(23,24) - the skilled work required and

application to the formwork are different, however.

Ask our support department to advise you on the opti-

mum solution.

*as defined by CIRIA Report C511 “Controlled Permeability Formwork“

20

Zemdrain®

Transport / Marine / Waterway Structure

Brighton, England Donegal, Ireland

Freeport, Bahamas Doha Corniche, UAE

King George V Dock, London; UK Skullerund Bridge, Norway

Oresund Link, Sweden/Denmark Charles de Gaulle Airport, Paris, France

21

Zemdrain®

Potable Water / Wastewater Structures

Spillway, Alabama, USA

Dam, Ireland

Service Reservoir, England

WTW, GermanyDam, Germany

22

Zemdrain®

Practical applications on formwork

Lining steel formwork for bridge pier with Zemdrain® MD Formwork element for bridge lined with Zemdrain® Classic

Frame formwork for a drinking water reservoir lined with

Zemdrain® MDSoffit of bridge over a canal lined with Zemdrain® Classic

Round convex steel formwork lined with Zemdrain® Classic Formwork for a bridge pier curving in two directions lined

with Zemdrain® MD

23

Zemdrain®

Practical applications on formwork

Featured bridge pier formwork lined with Zemdrain® MD Steel formwork for a sea wall lined with Zemdrain® Classic

Bridge parapet formwork lined with Zemdrain® MD Steel formwork for outflow cone in sewage purification basin

lined with Zemdrain® Classic

Lining a small detail shutter - gaps between the individual

shutter panels are bridged with Zemdrain® ClassicInternal flexible formwork lined with Zemdrain® Classic

24

Zemdrain®

Specification Clauses

1. All formed surface finishes are to be achieved using a Type III controlled permeability formwork(CPF) liner, comprising a filter fabric bonded to a backing grid, Zemdrain® MD or equal approved.

2. The approved Type III CPF linershall have the following properties:■ a maximum compression of less

than 10 % under a pressure of200 kPa

■ a maximum pore size of lessthan 0.050 mm

■ a minimum water retention capa-city of 1.30 litres/m2

■ a maximum absorbency of 0.1 litres/m2

3. The approved CPF liner shall havesupporting test data certified by an

independent testing organisation,such as the Board of Agrément, toconfirm the achievable improve-ments to concrete.

4. Certification and independenttesting shall demonstrate that theuse of the CPF liner improves theperformance of a CPF cast concre-te against that for conventionallycast concrete. The outer 20 mm ofthe CPF cast surfaces shall havecement contents of over 75 kg/m3

greater than the control. A mini-mum improvement of 50 % for sur-face tensile strength, ISAT, carbo-nation and chloride ingress is alsorequired. Liners without an Agré-ment Board Certificate and inde-pendent tests to establish the linerperformance shall not be approved.

5. The CPF liner shall be installed andused in accordance with the manu-facturer's recommendations. Theuse of release agents is not permit-ted.

6. Type III, CPF liners can be reused,subject to inspection betweenpours. Before approval for liner reu-se is given, evidence that durabilitybenefits are maintained with reusemust be submitted.

7. A trial panel shall be cast to confirmthe suitability of the liner for usewith the design mix and formwork

8. Type III, CPF liners are as defined in the Concrete Society / CIRIA Report “Controlled PermeabilityFormwork“ CIRIA C511.

1. All formed surface finishes are tobe achieved using a controlled per-meability formwork (CPF) liner,Zemdrain® MD, Zemdrain® Classicor equal approved.

2. Approved CPF liners shall have thefollowing properties:■ a maximum compression of 10 %

under a pressure of 200 kPa■ a maximum pore size of 0.050

mm■ a minimum water retention capa-

city of 0.35 litres/m2

■ a maximum absorbency of 0.1 litres/m2

3. The approved CPF liner shall havesupporting test data certified by an

independent testing organisation,such as the Board of Agrément, to confirm the achievable improve-ments to concrete.

4. Certification and independenttesting shall demonstrate that theuse of the CPF liner improves theperformance of a CPF cast concre-te against that for conventionallycast concrete. The outer 20 mm ofthe CPF surfaces shall have ce-ment contents of over 75 kg/m3

greater than the control. A mini-mum improvement of 50 % for sur-face tensile strength, ISAT, carbo-nation and chloride ingress is alsorequired. Liners without an Agré-ment Board Certificate and inde-

pendent tests to establish the linerperformance shall not be appro-ved.

5. The CPF liner shall be installed andused in accordance with the manu-facturer's recommendations. Theuse of release agents is not permit-ted.

6. Single sheet CPF liners can beused once. Composite sheet/netCPF liners can be reused up tothree times, subject to inspectionbetween pours. Before approval forliner reuse is given, evidence thatdurability benefits are maintainedwith reuse must be submitted.

Zemdrain® MD

Zemdrain® MD and/or Zemdrain® Classic

Zemdrain®

Zemdrain® MD product range

Article Roll width Roll length m2/roll weight/rollnumber

ZEMMD2 2.50 m 35 m 87.5 59 kg

can be reused subject to correct handling and cleaning

Product

Tools for working with Zemdrain® MD

Zemdrain® MD

Article Desriptionnumber

ZEMSCHNITTQ Cross cutting rolls to shorten roll lengthZEMSCHNITTL Cutting the complete roll to reduce roll width

ZBBAND MD fixing tape 50 mm x 1.0 mm x 10 lin. m/roll ZBBAND25 MD fixing tape 25 mm x 1.0 mm x 10 lin. m/roll

Double-side adhesive tape, for fixing and sealing of Zemdrain® MD to formwork (it is possible thatsome isolated small blowholes will occur in the vicinity of the adhesive tape due to the impermea-bility of the adhesive film.

ZABAND Zemdrain® cover tape 50 mm x 0.5 mm x 10 lin. mZABAND25 Zemdrain® cover tape 25 mm x 0.5 mm x 10 lin. m

Zemdrain® laminated self-adhesive tape for covering formwork joints, stapled Zemdrain® joints, for repair of any damaged Zemdrain® areas or for edge coverage of lined used formwork elements(it is possible that some isolated small blowholes will occur in the vicinity of the adhesive tape dueto the impermeability of the adhesive film).

ZDSSKBSpecial adhesive tape 50 mm x 0.5 mm x 50 lin. mDouble-sided adhesion for preferred fixing of Zemdrain® MD formwork liner to formwork faceswhen staples should not be visible

Cuts

Article Descriptionnumber

ZSZMD2500Tensioning tool MD 2.5 mfor tensioning of Zemdrain® MD (also available in 0.6 m and 1.2 m)

ZTAKMD1Adjustable stapler, hand-operated for fixing Zemdrain® MD to formwork surfaces for staple size 8 and 10 mm

Additional staplesZTEK08 Model 053-8 mm long, 1400 no./pack. for coated plywood panelsZTEK10 Model 053-10 mm long, 1200 no./pack. for plywood panels

ZSTMKL Steel Knife with blade

General accessories for Zemdrain® MD and Zemdrain® Classic Article Descriptionnumber

ZVBANDZemdrain® pre-fixing tape 50 mm x 2 mm – 10 lin. mfor sealing formwork joints and formwork elements joints

FKBANDSFoam plastic waterstop 19 mm x 6 mm – 10 lin. mfor sealing formwork element joints

ZFSS180Serrated grinding wheel SIC 24 - Ø 180 x 22.2 mm – 80 m/sec.Special grinding wheel for grinding off large burrs and corners on hardened concrete

ZFSS115Serrated grinding wheel SIC 24 - Ø 115 x 22.2 mm – 80 m/sec.Special grinding wheel for grinding off large burrs and corners on hardened concrete

ZSBRILLEProtective gogglesEssential eye protection for carrying out concrete grinding work

ZSFMASKDust protection maskused as respiratory protection when carrying out grinding work on dry concrete,packaging unit 10 pcs.

25

Article Roll width Roll length m2/Roll weight/RollnumberZEM1600 1,60 m 50 m 80,0 28 kgZEM1900 1,90 m 50 m 85,0 33 kgZEM2250 2,25 m 50 m 112,5 39 kgZEM2600 2,60 m 50 m 130,0 45 kgZEM2900 2,90 m 50 m 145,0 50 kgZEM3200 3,20 m 50 m 160,0 55 kgZEM4000 4,00 m 50 m 200,0 70 kgZEM4500 4,50 m 50 m 225,0 78 kgZEM5200 5,20 m 50 m 260,0 89 kgSpecial widths are available on request, subject to a minimum quantity and increased delivery time

26

Zemdrain®

Zemdrain® Classic and accessories

Product

Zemdrain®

Classic roll

Article Descriptionnumber

ZEMSCHNITTQ Cross cutting rolls to shorten roll lengthZEMSCHNITTL Cutting the complete roll to reduce roll width

ZEMSCHWEIßWelding for increasing roll widthWelding seam length

ZDSSKBSpecial adhesive tape 50 mm x 0.5 mm x 50 lin. mDouble-sided adhesive, for fixing rear face and sealing butt joints on Zemdrain® Classic

Cuts

Tools for working with Zemdrain® ClassicArticle Descriptionnumber

ZSZKAZTensioning toolWide-area clamping and tensioning of Zemdrain® Classic across smaller formwork areas. Fix subsequently using staples.

ZTAKHANDStapler, hand-operated for fixing Zemdrain® Classic to 8/10 timbers and to formwork skin or sub construction for staple sizes 6 and 8 mm

Additional staplersZTEK06 Model 053-6 mm long, 1800 no./pack for playwood panelsZTEK08 Model 053-8 mm long, 1400 no./pack for timber and softwood

ZSTMKL Steel Knife with blade

ZHWSCH Heavy duty scissors for simple cutting and shaping work with Zemdrain® Classic

Article Description Size Tensioning No. reqd./m Weightnumber length cm kg/item

ZSH050Tensioning hooks

50 from 20 – 25 4 – 5 0.05ZSH100 100 from 35 – 45 2 – 3 0.06ZSH150 150 from 40 – 50 2 – 3 0.08

Article Description Size Packaging unitnumber

ZEG050Spare rubber band

50 50 pcs./bundleZEG100 100 50 pcs./bundleZEG150 150 50 pcs./bundle

Article Description Weightnumber kg/item

ZSF0810

Tensioning FrogFix approx. 1 per meter to formwork surface, and place 8 x 10 timber in tensioning frogs - length depends on formwork element length. Pretension 2,8 tensioning frog, staple Zemdrain® Classic to timber, release lock and Zemdrains® Classic remains tensioned

Accessories

27

To obtain the best results withZemdrain®, the following should beobserved:

1. Zemdrain® Classic is best suited touse with flat, convex or soffit forms.Zemdrain® MD can be used withnearly all shapes of formwork. Forsteel forms special provisions mustbe made for use of the liner.

2. The form face should be conti-nuous, flat, clean and oil free. Withlower grade plywood, the faceshould be sealed to prevent wateringress/sugar egress. Tape anyjoints where oil may have concen-trated.

3. It is important that Zemdrain® linerslie flat on the form. This is aided byfixing during warm sunny periods(the liner expands/contracts whenexposed to and shaded from thesun). In times of high daily/weeklytemperature variations (>10° C), ca-re is required to ensure that the linerremains flat. The use of speciallydesigned fixing tools helps to ensu-re correct fixation.

4. Release agents should not be ap-plied to the form or to the liner. Takecare to avoid all contamination.

5. Zemdrain® can be easily cut usinga blade cutter or scissors and atta-ched to the form using an industrialstapler and 10 mm staples. Oncethe liner is in place, holes for the tiebolts are cut and stapled.

6. Any damaged areas should be cutout and replaced. Put in a new pie-ce of Zemdrain® on top of the old,cut through both, remove damagedarea and replace with the new piece.

7. To avoid visible marks on the con-crete surface, at tie bolt holes andunder spacer blocks the maximumpressure on Zemdrain® should notexceed 2 MPa (20 kg/cm2).

8. Concrete should be placed andcompacted in accordance with ac-cepted good practice. Pouring andvibration of concrete should be per-formed consecutively without delay.■ ensure concrete is not dischar-

ged against the liner surface andminimise splatter

■ the slump should be maintainedat the mid to lower end of thepermissible range

■ avoid concrete wetting the surfa-ce of the liner and then being al-lowed to dry

■ keep the vibrator at least 5-10cm from the form face

■ avoid fast extraction of the vibra-tor

■ avoid excessive and irregular vi-bration

Failure to observe any of the above,may result in prominent pour lines,colour variations, segregation or thepresence of blowholes.

9. Primary vibration must be perfor-med using an internal poker vibra-tor. External vibrators should onlybe used after completion of primaryvibration.

10. Some blowholes and lighter colou-red concrete can occur in the up-per 5-10 cm of a pour. This can beavoided by revibration of this zone(after 20-50 mins), followed by tam-ping and smoothing of the surface.This is especially important forpours with inclined top shutters andwhen using Classic.

11. Rolls of Zemdrain® should be sto-red in a clean environment, awayfrom contaminants and prolongedexposure to UV light. In cold weat-her, rolls should be stored indoors.Zemdrain® should be protectedfrom flames, welding or steel cut-ting and kept free from dirt anddust.

12. The number of uses for Zemdrain®

Classic and MD will depend uponthe reasons for liner use (for durabi-lity or surface blemish removal) andwill be subject to proper handlingand cleaning. Checks for possiblemechanical damage to the skin ofthe liner or the tape should be ma-de between uses.

13. The used liner is chemically inert

and can be disposed of by burying,earth dumping or incineration. A“Material Safety Data Sheet“ isavailable upon request.

Note:a) Zemdrain® cast concrete will gene-

rally be slightly darker than traditio-nally cast concrete reflecting thecolour of the cement. Darker colou-red spacer blocks may be requiredfor soffits. GGBS lightens thecolour.

b) Fillets and features should be pla-ced on top of the fitted liner. Largerfeatures, (width > 100 mm) can belined individually. Smaller featuresare usually left unlined or can be lined using Zemdrain® tape.

c) Minimise any staple marks in the finished surface by ensuring staplesare flush to the liner. Staples andjoints can be covered using Zem-drain® tape. Some blowholes mayoccur at the tape.

d) Cleaning of MD with a high-pres-sure water jet between uses is recommended. Particular attentionshould be paid to the upper half ofthe form. The liner should remain fixed to the form during cleaning.

e) Surface colour variations may occurdue to variable vibration, plywoodquality, the mix used and the num-ber of uses of the liner. Thesecolour variations do not effect con-crete quality.

f) If a Zemdrain® lined form is left ex-posed to full sun for a period of ti-me, it should be left to cool downfor several hours before concreting.

These Technical Guidelines and the Fixing Details overleaf are acondensed description of factorshaving a direct effect on the perfor-mance of Zemdrain® CPF Linersand are based on the present stateof the art. It may be necessary toalter these recommendations, asmore information becomes availa-ble. If in doubt consult your localsupplier.

Zemdrain®

Technical Guidelines

28

1. For successful fixing of Zem-drain® MD, you require the follo-wing:

■ Staple gun (using 10/12 mm staples)■ Special fixing tools (available in

widths of 0.6 m, 1.25 m and 2.5 m)

2. The following are general noteson fixing Zemdrain® MD:

■ before using refer to the TechnicalGuidelines

■ after unrolling and cutting, allow linerto relax and warm up for at least 10minutes

■ in direct sunlight liner will expandand become easier to fix

■ before fixing, ensure liner is squareon the form to avoid distortions

■ always ensure staples are securelyplaced, hammer home if necessary

■ in cold weather MD should be sto-red in a heated environment prior tofixing

3. Zemdrain® MD can be fixed intwo ways:

■ with the length direction of the rollused in the vertical pour direction -PREFERRED

■ with the length direction of the rollused in the axial direction

4. Fixing when the length of the rollis in the vertical pour direction:

■ follow points under 2 above, thenstaple at 25 mm centres (max.)along the top edge

■ at other end, attach a fixing tool overthe full width and stretch MD flat byrotating the fixing tool against theedge, then staple down

■ for the cross direction, ensure that li-ner lies flat with no folds, pull tightwith fixing tool if necessary, stapledown at 30-50 mm centres

■ check that liner is tight with no di-stortions or folds evident

■ repeat above steps with additionalstrips of liner until the formwork iscovered

■ strips of liner are butted up and withcare tight joints can be achieved,otherwise put sealant in the joint

■ Zemdrain® tape can be used tomask the joint and the staples

■ form tie bolt holes using a knife, pla-ce some staples around the hole

■ for forms ( >2.5 m high) - pull linerflat and staple axially at 2.5 m inter-vals over the height, reattaching thefixing tool and pulling flat each time.

■ for forms (>2.5 m high) - tensioningclamps may be used to avoid the in-termediate rows of staples

5. Fixing when the length of the rollis at right angles to the pour di-rection:

■ liner should only be fitted this way ifthe form is less than 2.5 m high, forhigher forms, always fix with thelength of the roll in the vertical pourdirection

■ fixing should be as described in 2and 4 above

■ in the vertical pour direction a fixingtool should be used to ensure that liner lies flat and is tight. Care is re-quired to avoid distortions at thecorners.

6. Other formwork shapes

■ liner can be used with most formshapes, including convex, concaveand circular

■ slightly modified versions of the abo-ve techniques are applied

■ please consult your local supplier forfurther details

The above fixing details apply to flattimber / plywood faced forms. For steelfaced forms, it is recommended thattimber inserts be used to permit liner tobe stapled to the form. For unlined pa-nel systems, take care to ensure thatthere are no gaps between panels be-fore fitting the liner.

Zemdrain®

Fixing Guidelines - MD

3-5 cm

Zemdrain MD

2-3

29

Before using Classic refer to theTechnical Guidelines.

A. Classic must be tensioned in both

directions to avoid folds in the con-

crete. Due to its thermal expansion

properties, the liner should always

be left in the sun for at least 10

minutes before fitting and where

possible be fitted during the war-

mest part of the day. Wherever

possible the length of the roll

should be fitted in the vertical pour

direction.

B. Unroll Classic, cut to the required

length from the roll and place squa-

re on the form. Allow a minimum

overhang of 50 mm all round, with

approx. 200 mm at the end where

principal tensioning is performed.

Always tension in the length of the

roll first, followed by the cross di-

rection. The smooth grey side faces

the concrete.

B. For length direction - at the non-

tensioning end, staple Classic to

the form edge, not the face. At the

other end, attach the tensioning de-

vice and once the slack is taken up,

induce a minimum extension of 5

mm/metre length. Maintain tension

and staple down only after comple-

tion of tensioning in the cross direc-

tion.

C. For cross direction - at the non-ten-

sioning end, pull Classic flat and

staple down. At the other end, pull

hand tight, attach the tensioning

device and induce a minimum ex-

tension of 3 mm/metre width. Sta-

ple down and then finish stapling of

other face.

D. Either trim off the excess liner

or fold over the edge and staple

down. Form tie bolt holes after

tensioning is complete, using a

knife and stapler.

Notes:

1. In cold weather Classic should be

stored in a heated environment

prior to fixing

2. Use scissors or a knife to cut Clas-

sic

3. Use an industrial staple gun and

8 to 10 mm staples

4. When stapling, always work from

middle of section to end

5. Staples around edge of form

should be at maximum 25 mm cen-

tres (lengthways tensioning) and at

maximum 50 mm centres (crosswi-

se tensioning)

6. Special tools and techniques are

required to achieve the recommen-

ded extensions for lengths of up to

49.5 m:

a) tensioning frogs/belts (available

from distributors) are used for

lengthways tensioning for roll

lengths from 3.0 m up to 49.5 m

b) tensioning clamps (available from

distributors) are used for crossways

tensioning for roll widths up to

5.2 m

c) For curved formwork or non-ply-

wood faced formwork, guidance on

fixing should be sought from your

local distributor.

d) Specialist accessories such as

staplers, staples and tapes are also

available form distributors.

Zemdrain®

Fixing Guidelines - Classic

Zemdrain

A.

B.

C.

D.

tensioningdevice

5 mm/metrelength

tie-bolt hole

3 mm/metrewidth

30

1. Damage

Repair of damaged areas. For small

areas use a short length of Zemdrain®

tape. For larger areas place a new

piece of Zemdrain® over the damaged

area and cut through both layers to

form an infill section. Remove the

damaged liner and replace with the

new piece using staples or tape.

2. Tie Bars

Holes for formwork ties should only be

formed after Zemdrain® has been com-

pletely fixed to the formwork. Cut a

clean hole with a blade cutter and for

extra security staple in place.

3. Release Agents

Release agents should not be used

with Zemdrain®. They can block the li-

ner pores or cause uneven swelling

making the liner unfit for use. Care

should be taken to avoid spillage of

diesel, hydraulic oil and other contami-

nants onto the liner.

4. Complicated Shapes

Zemdrain® MD is best for complicated

shapes. The liner has been successfully

used with circular, convex and concave

forms.

5. Joints

For Classic, the two pieces of liner are

simply overlapped and stapled down.

For MD, the two pieces are butt jointed

with both stapled down. For good

joints no further action is required. For

poor joints the gap should be filled with

a sealant or covered with Zemdrain®

tape.

6. Spacers

In order to reduce visible imprints on

the concrete, such as those caused by

spacers, the maximum pressure on

Zemdrain® should be less than 20

kg/cm2. Loading caused by reinforce-

ment should be distributed onto as

many spacers as possible

7. Drainage Path

For Classic, it is essential that the bot-

tom of the liner is open to the atmos-

phere to permit unimpeded drainage.

For MD, there is usually sufficient stora-

ge capacity within the net to accom-

modate all water removed from the

concrete.

8. Steel Faced Formwork

Zemdrain® Classic and MD can be

used with steel faced formwork. Speci-

al fixing techniques may be required

depending upon the dimensions of the

formwork.

It is essential when using Zemdrain®

with steel faced forms to design in the

liner fixing details at the time of manu-

facture of the form.

9. Panel Systems

Zemdrain® MD has been used

successfully with large panel systems

without the need for oversheeting with

additional plywood. Care needs to be

taken to ensure that there are no

gaps between panels before fitting

Zemdrain®. The resulting surface is not

completely flat but is acceptable for

most non-visual applications.

10. Concrete Colour

The colour of the finished concrete is

primarily a function of the type of ce-

ment used. Hence for white cement

the concrete colour remains white. For

GGBS the colour will be light grey, with

other cements giving a darker colour.

The fine aggregate will also have

some influence on the colour, as will

the amount and uniformity of vibration

and curing.

11. Other Questions

If you have any other questions please

call us or visit the Zemdrain® web page

at www.zemdrain.com.

Zemdrain® MDFrequently asked questions

Zemdrain® has been tested and approved at numerous universities, institutes, laboratories and on construction sites. In addition to test reports, copies of which are available upon request, there are several independent publications which document the benefits of using a controlled permeability formwork liner.

Test Certificates:A. “Zemdrain® CPF“. British Board of Agrément Certificate No 94/3072. B. “Investigation of the growth of micro-organisms on materials used in the drinking water sector“. Test certificate No

W315D/94. Hygienic Institute, Gelsenkirchen. C. “Tests of effect on water quality of Zemdrain® CPF liner to BS6920“. Report No M100281,WRc, UK.

References:1. Wilson, D. “Durability Problems - is formwork the cause?“ Concrete Engineering Summer 2001 2. Monks, W. “The Control of Blemishes in Concrete. Appearance Matters“. BCA. 19873. Price, WF. “Controlled Permeability Formwork“. CIRIA Report C511, London, 20004. Price, WF. “Curing Concrete“. Current Practice Sheet No. 112. Concrete Magazine, September 1998.5. Wallbank, EJ. “Performance of concrete in bridges. A survey of 200 highway bridges“. HMSO. 19896. Price, WF and Widdows, SJ. “The effects of permeable formwork on the surface properties of concrete“. Magazine of

Concrete Research, 43, No. 155, June 19917. Price, WF. “CPF“. Concrete Society Current Practice Sheet No 117. Concrete Magazine, May 19998. Dhir, RK et al. “Total design using CPF“. CTU Report 1399, University of Dundee. 1999 9. “Formwork - A guide to good practice 2nd edition“. Concrete Society, 199510. Price, WF. “The effect of Zemdrain® CPF on the frost resistance of concrete“. TEL Report 1303/92/634911. Reeves, SJ. “The effect of formwork permeability on algae growth on concrete surfaces“ Bath. 199312. Monks, B. “Plain formed concrete finishes“. Concrete Society Technical Report No. 52, 199913. Price, WF. “The use of Zemdrain CPF for blended cement concretes “. TEL Report 1303/92/615714. Coutino, JS. “Effect of CPF on white concrete“. ACI Materials Journal. March-April 2001 15. Price, WF. “High Performance concrete in practice“. Quality Concrete Part II. May 199516. Basheer, PAM et al. “Influence of CPF on the durability of concrete“. Concrete 2000, Dundee.17. Rankin, GIB. “In-situ evaluation of surface properties of concrete cast using Zemdrain®“. Report No TAS9959. 199918. McCarthy et al. “Tackling chloride ingress and corrosion: the role of CPF“, Concrete Magazine February 200219. “Guide to the construction of reinforced concrete in the Arabian Peninsula“. CIRIA Report CP/62, London 200120. Price, WF & Widdows, SJ. “Durability of concrete in hot climates: Benefits from permeable formwork“. Proceedings 3rd

International Rilem Conference. “Concrete in Hot Climates“, Torquay, 199321. Basheer, M. et al. “CPF: Influence on carbonation and chloride ingress in concrete“. Proceedings International Conferen-

ce. “Concrete under severe conditions Consec 95“, Sapporo 199522. Seyfried, Prof. “Economic feasibility study on the usage of Zemdrain®“. ISAH, Hanover, 199523. Beddoe, RE. “Comparison of concrete surfaces formed with the formwork liners Zemdrain® Classic and Zemdrain® MD“.

Technical University of Munich. Report No 3360-03-06. 1996 24. Beddoe, RE. “Concrete surfaces produced with CPF: Durability and effect of liner reuse“. Concrete 2000. Dundee. 199925. McCarthy et al. “Specifying concrete for chloride environments using CPF“, Materials and structures, Vol 34, Nov 2001,

pp 566 – 57626. BRE Special Digest 1. “Concrete in aggressive ground“ BRE 200127. BS8500:1:2002 Complementary standard to EN206-1, Part 1, “Method of Specifying and guidance for the specifier“.

BSI 2002 28. “Guide to the construction of reinforced concrete in the Arabian Peninsula“ Concrete Society / CIRIA 2002

This information corresponds to our current state of knowledge in the fields described, and is intended to give you as manyhelpful suggestions as possible for your own procedures, which it cannot replace. For each application we recommend that atrial panel be cast using the intended design mix and formwork to ascertain specific performance. As soon as new experienceor findings arise it will be revised. DuPont and Max Frank undertake no guarantee, liability or other responsibility for test or wor-king results which are reproduced in connection with this information. This publication gives no grounds for a licence and isnot intended to infringe existing industrial property rights belonging to third parties.

Zemdrain® is DuPont's registered trademarkwww.zemdrain.com

Zemdrain®

Test certificate / References

31

32

150,00

17,00

Max Frank GmbH & Co. KGAccessories for the reinforced concrete constructionMitterweg 1 · D-94339 Leiblfinghttp://www.maxfrank.deE-mail: [email protected]

Sales Phone +49/(0)94 27/189-0Fax +49/(0)94 27/189-220Technical advisory servicePhone +44/(0)79 68 29 84 39Fax +44/(0)79 68 29 84 46 17

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