Sikaflex Construction

 

Revised March 2006

Sikaflex-Construction Construction

Sikaflex®-Construction

Polyurethane joint sealant for construction purposes

Description Sikaflex-Construction is a one component thixotropic polyurethane based

joint sealant. It cures under the influence of atmospheric moisture to form an

elastomeric material with adhesive properties in some cases without the

need for priming of the substrate.

Uses An elastic joint sealant on cement based substrates such as:

???? Expansion joints in buildings and civil structures above and below

ground.

???? Joints in precast concrete elements such as facades and tilt-up panels.

???? External walling and cladding joints.

???? Curtain walling.

???? Retaining walls.

Advantages ???? New Sikaflex-Construction will bond to well cleaned old Sikaflex-

Construction.

???? Excellent adhesion on all cement based materials.

???? High durability.

???? Good weathering resistance.

???? Easy to use.

???? Short cut off string even after storage.

???? Ready for immediate use – no mixing saves time.

???? No potential mixing errors or wastage due to mixed quantities being

greater than required.

???? Non-corrosive.

???? Can be painted over with many water solvent and rubber based paints

(preliminary tests recommended).

Storage and Shelf Life When stored in cool dry conditions between 10°C and 25°C unopened

Sikaflex-Construction will keep for a minimum of twelve (12) months.

Instructions for Use

Surface Preparation

Clean sound dry and free of oil grease and surface contaminants such as

form release agents curing membranes and hydrophobic water repellents.

Any loose particles or laitance should be removed with a rotary mechanical

wire brush followed by blowing out with oil free compressed air. Use Sika

cementitious or epoxy mortars for making good spalled or damaged joints.

Priming (Refer Primer Selection Guide for detailed information. This is a

separate document).

Application Slide unipac into the special applicator gun then either “nick” the unipac

wrapper at the extrusion end or cut off the very end of the unipac if it contains

partially cured lumpy Sikaflex. Fit the gun with a suitable nozzle that has

been cut to deliver the right bead size.

All primer on joint sides which is generally applied after backer rods or

release tapes are in place (refer joint design section) must have not exceeded

it’s open time and it must be thoroughly dry and not just skinned over;

otherwise in conditions of rising temperature trapped solvent can blow

bubbles in the uncured sealant.

Very porous substrates such as poorly compacted or cracked concrete must

have their porous bond area surfaces thoroughly sealed to avoid the

possibility of air bubbles being blown into the uncured sealant if the substrate

temperature rises.

Extrude the Sikaflex-Construction into the joint ensuring that no air is trapped

in the joint. Wide joints will require more than one pass of the application gun

to make sure that Sikaflex-Construction is in full contact with the sides and

bottom of the joint. Tooling-off the sealant will assist by forcing the sealant

Revised March 2006

Sikaflex-Construction

Construction

Application (continued) into the joint against it’s sides and back up material; this will also break any

air bubbles and expose any air pockets.

Final tooling of the joint surface can be done effectively with a spatula dipped

in a 20% solution of washing up detergent in water (test to ensure it does not

discolour the cured Sikaflex-Construction) or a profiled piece of raw potato.

When tooling off with detergent solution ensure no solution is allowed to get

onto adjacent joint sides/bonding areas before the sealant has reached the

final tooling stage in those locations. When masking sides of joints for

neatness remove tape before the sealant cures. Always allow sufficient

surface exposed to moisture.

In conditions of low atmospheric humidity say less than 45% R.H. at 20°C or

<60% R.H. At 10°C when early joint movement is anticipated (eg. the joint

has been sealed in the later afternoon sun and at sunset a rapid temperature

drop is expected – Canberra or Alice Springs in winter) it is advisable to

spray the surface of the tooled Sikaflex with a fine mist of water to promote

early skinning. Seal joints in walls facing west in the morning.

Cleaning Use Sika Colma Cleaner to remove uncured sealant from tools after first

removing the bulk of the Sikaflex material with a scraper followed by a rag or

paper tissue. Sikaflex Hand Cleaner will remove fresh and partially cured

Sikaflex from the skin. Hardened material can only be removed mechanically.

Joint Design Permissible change in joint width at ambient temperatures:

???? Above 0°C is ±25% of average joint width at the time of sealing

???? Below 0°C is a total of ±12½% of average joint width at the time of

sealing

???? Admissible total shear movement is 20% of joint width at the time of

sealing

For the successful sealing of joints with Sikaflex-Construction it is essential

that the following guidelines on joint configuration are observed:

For joints up to 12 mm wide width to depth ratio = 1 : 1

For joints over 12 mm wide width to depth ratio = 2 : 1

An approximate rule of thumb for joints in pre-cast concrete

Joint interval (metres)

Joint width (mm)

Up to 2.0

10

2.0-3.5

15

3.5-5.0

20

5.0-6.5

25

6.5-8.0

30

General Use:

To ensure that the correct width to depth ratio is achieved and to provide a

firm backing against which the sealant can be tooled off and also prevent the

sealant from adhering to the bottom of the joint the space under the Sikaflexconstruction

must be filled with a tight fitting non-rotting non-absorbent

backing material eg. fibreboard combined with a bond breaking tape (eg.

polypropylene or PVC) or alternatively an open cell polyurethane or closed

cell polyethylene backer rod supplied by Sika. Open cell PU backer rod has

the advantages of allowing moisture access to the front and back of the joint

simultaneously facilitating faster curing. Also open cell PU backer rod is

much more compressible than closed cell PE foam thus one diameter rod can

be used in a much wider range of joint widths. Closed cell PE backer rod can

cause bubbling in uncured sealant in rising temperature conditions if it’s outer

skin is punctured. It is essential that oil or tar impregnated backing materials

are not used.

Revised March 2006

Sikaflex-Construction

Construction

Criteria that have to be observed in designing expansion joints

Usually the joint has the following geometry:

For joint widths up to 12mm

Width = 1 or w=d

Depth 1

For joint widths 12mm to 50mm

Width = 1 or w=2d

Depth 0.5

For concrete and masonry joints subject

to movement the depth of the Sikaflex in the

joint has to be at least 8mm.

Technical Data (Typical)

Colours Concrete Grey

Density 1.4 kg/litre

Basis Moisture curing polyurethane prepolymer

Priming Refer separate Primer Selection Guide

Application temperature 5°C to 40°C

Service temperature -30°C to 70°C (maximum +40°C in water and temporarily +50°C)

Shore A Hardness (DIN

53 505)

<35 after 28 days (at 23°C 50% R.H.)

Elastic Recovery (DIN 52

458)

>80%

Tensile strength (DIN 52

455)

<0.6 MPa @ 60% elongation @ -20°C

<0.4 MPa @ 100% elongation @ +23°C

Elongation at break (DIN

455)

>400%

Tensile strength at break

(DIN 53 455)

>1 MPa

Maximum working

expansion and

contraction

Refer Joint Design section

Skinning Time (at 23°C

50% R.H.)

4 to 6 hours

The “bottom” of the joint must not restrict

the deformation of the sealant since this

could result in failure during the opening

of the joint. The depth of the joint should

be adjusted by inserting a suitable joint

backing material.

In corner joints too the insertion of a release

tape or backer rod is required otherwise the

sealant will fall during expansion of the joint.

The edges or corners of

concrete joints are often

weak because of poorly

compacted concrete thus

it is desirable to use

chamfers and recess the

joint

Revised March 2006

Sikaflex-Construction

Construction

Cure rate (at 23°C 50%

R.H.)

2 mm per day

Chemical Resistance

(rough guide only)

Long Term

Water

Sea water

Dilute mineral acids

Dilute mineral alkalis

Domestic sewage

Medium Term

Mineral oils

Vegetable oils

Fats

Swimming/spa pool water

Fuel oils

Low to Very Low

Organic solvents

Paint dilutents

Strong acids

Strong alkalis

Consumption Sika Primer 1 13 ) About 4-5m² per litre of primer. As a guide a

) 250 ml can of primer will normally be

) sufficient for about 35-40 running metres of

) 12.5 mm (deep joint).

Approx. 5-8 m²/litre

Sikaflex Estimating Chart

Quantities: a guide to Sikaflex-Construction quantities (for fillet work multiply metre runs per ‘unipac’ by two).

Joint size in mm Litre Sikaflex-Construction

per metre run

Metre run

Per ‘unipac’ (600 ml)

5 x 5 0.025 24

5 x 10 0.050 12

5 x 15 0.075 8.0

10 x 10 0.100 6.0

10 x 15 0.150 4.0

10 x 20 0.200 3.0

10 x 25 0.250 2.4

15 x 10 0.150 3.9

15 x 15 0.225 2.7

15 x 20 0.300 2.0

15 x 25 0.375 1.6

15 x 30 0.450 1.3

15 x 40 0.600 1.0

20 x 10 0.200 3.0

20 x 15 0.050 2.0

20 x 20 0.400 1.5

25 x 12.5 0.310 2.0

25 x 15 0.380 1.6

25 x 20 0.500 1.2

25 x 25 0.630 0.9

30 x 15 0.450 1.3

30 x 20 0.600 1.0

30 x 25 0.750 0.8

40 x 20 0.800 0.8

40 x 25 1.000 0.6

40 x 30 1.200 0.5

Packaging 600 ml unipac per carton of 20

Sika Primers are supplied in 250 ml cans (Flammable)

Sika Colma Cleaner is supplied in 1 litre and 20 litre cans (Flammable)

Important Notes ???? Sikaflex-Construction is best stored at temperatures between 10°C and

25°C in dry areas. The storage temperature should not exceed 30°C for

extended periods.

???? For best results use opened unipac the same day otherwise the Sikaflex-

Construction in the nozzle will cure and have to be removed.

???? When applying sealant avoid air entrapment.

???? Joint movement must not exceed ±25% (above 0°C) of the width of the

joint at the time it is sealed.

???? Joints in low humidity environments should be sprayed with a mist of

water as soon as tooling off is complete to accelerate the curing process

Revised March 2006

Construction Sikaflex-Construction

 

Important Notes

(continued)

and minimise the risk of early movement cracks.

???? For specific chemical resistance please contact our Technical Service

Department.

???? If there is no history of a particular coating/paint being applied over cured

Sikaflex-Construction for a period of six months or more an

overpaintability test should be made to determine:

i) that the paint dries properly within the expected time frame.

ii) That if the paint film dries satisfactorily it is not subsequently

softened and/or stained where it comes into contact with the

Sikaflex-Construction when exposed to the heat of the sun.

iii) That the adhesion of the paint/coating is satisfactory to the

Sikaflex-Construction.

Conduct a simple test overpaint a cured sample of Sikaflex-Construction

allow the normal drying time for the coating to elapse and then expose it to a

temperature of 80°C continuously for seven days. Sika’s technical

department can conduct this testing.

???? Do not paint Sikaflex-Construction with Sikagard-680S – it will not dry

satisfactorily.

???? Do not use Sikaflex-Construction to seal joints in chlorinated swimming

pools or spa pools because occasional over dosing with chlorine etc. can

eventually cause the Sikaflex-Construction surface to become sticky.

???? Where possible backer rod should be placed in a joint before it is primed.

???? Do not twist or puncture closed cell polyurethane backer rod during

installation this can lead to “out gassing”. The gas from the backer rod

blows bubbles into freshly applied Sikaflex-Construction during conditions

of rising temperature.

???? Open cell backer rod allows moist air access to the bottom of the joint so

that the Sikaflex-Construction can cure simultaneously from the front and

back of the joint.

???? Sikaflex-Construction should be used with care resealing joints that were

previously filled with silicone sealant. Consult our Technical Department.

???? Not to be used in glazing applications where the Sikaflex to glass bond is

exposed to direct or indirect sunlight or UV radiation.

Handling Precautions Sika sealants are generally harmless provided that certain precautions

normally taken when handling chemicals are observed. The uncured

materials must not for instance be allowed to come into contact with

foodstuffs or food utensils and measures should also be taken to prevent the

uncured materials from coming into contact with the skin since people with

particularly sensitive skin may be affected. The use of protecting clothing

goggles barrier creams and rubber gloves is recommended. The skin should

be thoroughly cleansed at the end of each working period either by washing

with soap and warm water or by using a resin removing cream – the use of

powerful solvents is to be avoided. Disposable paper towels not cloth towels

should be used to dry the skin. Adequate ventilation of the working area is

recommended. In case of accidental eye or mouth contact flush with water.

Consult a doctor immediately.

Important Notification The information and in particular the recommendations relating to the application and

end-use of Sika’s products are given in good faith based on Sika’s current knowledge

and experience of the products when properly stored handled and applied under

normal conditions. In practice the differences in materials substrates and actual site

conditions are such that no warranty in respect of merchantability or of fitness for a

particular purpose nor any liability arising out of any legal relationship whatsoever can

be inferred either from this information or from any written recommendations or from

any other advice offered. The proprietary rights of third parties must be observed. All

orders are accepted subject of our terms and conditions of sale. Users should always

refer to the most recent issue of the Technical Data Sheet for the product concerned

copies of which will be supplied on request.

PLEASE CONSULT OUR TECHNICAL DEPARTMENT FOR FURTHER

INFORMATION.