
What is RubberElast®?
RubberElast® sealing strip is worldwide successfully used in pre-cast component joints. On sites it is simply glued by pressing to the faying surface of a concrete component, and the joint of the concrete components becomes waterproof.
Why to use RubberElast®?
RubberElast® features an extremely high impermeability to water and gases, as well as an excellent resistance against atmospheric influence and mechanical wear.
RubberElast® even remains elastic at low temperatures. This sealing strip features an excellent adhesion not only to concrete, but also this sealing strip to metals, glass and other materials.
Sealing of pre-cast concrete components:
Industrially manufactured pre-cast components are taking larger and larger market share, as working with concrete on site is getting more expensive, and the construction work progress can be significantly accelerated. However, it has been still expensive and complicated to seal joints of the components properly. All solutions had their sticking points. In shaft production, there were only pre-fabricated sealing rings, however only available for standardsize round shaft components. Another solution was a classic grouting, however there is an extremely high risk of tearing, even in the case of small joint
deformation. Hydrophilic gaskets require additional covering by a minimum layer of concrete. Bitumenbased outer sealing usually provides no sufficient resistance against the water under pressure.
RubberElast® is a material that can be easily and quickly applied with almost no dependence on the temperature. The material becomes watertight immediately after application, as it is firmly glued to the concrete components by pressing. The material remains tixotrop. Its resistance against aggressive media makes RubberElast® suitable for sewage. Its safety is guaranteed by the Test Certificate by the Materials Testing Institute in Braunschweig, Germany.
RubberElast® (RubberNEK®) was tested by Material Testing Authority in Braunschweig. That is documented by General Construction Inspection Ceritficate No. P-5147/5783 MPA-BS.
RubberElast® (RubberNEK®) sealing tape serves for sealing of joints of precast concrete parts made of water-tight concrete against water under pressure and without pressure, as well as against earth humidity, as prescribed by DIN 18195 Part 4 – 6, acc. to List of Construction Rules A, Part 2, running No. 1.4.
Tightness test
Tightness of RubberNEK® was tested on a construction part at 80% compression. The results are given in the table below.
Joint |
Water pressure
(bar) |
Action time(hours)
|
Test result |
expanded by
0,25 mm |
0,5 |
24 |
tight |
1,0 |
24 |
tight |
1,5 |
240 |
tight |
additionally
displaced
by 7 mm |
0,5 |
24 |
tight |
1,0 |
24 |
tight |
1,5 |
144 |
tight |
2,0 |
24 |
tight |
2,5 |
24 |
tight |
3,0 |
24 |
tight |
Behaviour in Ca(OH)2 and during storage at high temperature
After 28 days storage of SynkoFlex® sealig tape in saturated Ca(OH)2 solution, or in the air of 60°C temperature, no changes in mass, shape and consistency were determined.
Pressure resistance
Pressure resistance of RubberNEK® was tested at normal climate on three samples at compressions up to 80%.
Adhesion tensile strength
Adhesion tensile strength was tested on 3 samples after they had been stored in different ways. The respectively determined values are given in the table below. Thereby, loads were applied via a steel prop D = 50 mm at 2 mm / min velocity.
Storage period and type |
Adhesion strength
(kPa) |
Fracture strain
(%) |
23°C, 50% humidity , 14 days |
74 |
9,6 |
under water , 20°C , 14 days |
56 |
13,3 |
8°C, 3 days |
120 |
16,4 |
Miscellaneous
Furthermore, RubberElast® is tested by means of thermo-graviemtric analysis and infra-red spectrum.
Assembly Instructions
RubberElast®

1. To achieve good gluing of RubberElast, make sure that the concrete base is dry and clean, and there is no cement paste, dust, separating agents, curing compounds or other substances diminishing adhesion.
2. Place RubberElast together with its protection paper in the middle of the butt surface and firmly press it at its whole length to avoid displacing of the seal during applying the next component.
3. To connect two ends of the strip, cut them at 30°- 45° angle so that they are jointed one above another before being pressed onto the component.

4. When you are going to place the next component, remove the protection tape and check whether RubberElast® sealing strip is firmly attached and not misaligned.
5. To achieve the best possible sealing acc. to GTC, please observe that the material is compressed to 20% (joint width = 5.6 mm) of its original height before stressing of the joint.