Waterproofing of concrete bridge decks


ISOFLEX-PU 500 One-component, polyurethane, waterproofing liquid membrane

PRIMER-PU 100 One-component polyurethane primer

PRIMER-PU 140 Two-component polyurethane primer for surfaces with high moisture content

DUROCRET-PLUS Polymer-modified, fiber-reinforced, repairing cement mortar

FLEX PU-30 S/FLEX PU-2K Polyurethane sealants

ACCELERATOR 5000 Special set accelerator for ISOFLEX-PU 500



Substrate preparation

The substrate must be dry (moisture content < 4%) and free from loose particles, dust, grease, etc.

Local restorations or repairs of the substrate (concrete, cement mortar etc) are carried out with the polymer-modified, fiber-reinforced cement mortar (PCC R3 type), DUROCRET-PLUS.

Any substrate cracks must be sealed with the polyurethane sealants FLEX PU-30 S or FLEX PU-2K.


Surface priming

The one-component, polyurethane primer PRIMER-PU 100 is applied on the clean, dry concrete surface (moisture content <4%), as long as the materials that may have been used for smoothing the substrate have dried. The primer is evenly applied on the whole surface with a brush, roller or by spraying.

Consumption of polyurethane primer PRIMER-PU 100: 200-300 g/m².

In case the substrate has moisture content > 4%, the PRIMER-PU 140 which is a polyurethane, two-component primer for surfaces with high moisture content is applied instead of the polyurethane primer PRIMER-PU 100.

Consumption of PRIMER-PU 140: 200-250 g/m².


Application of the polyurethane, liquid waterproofing membrane ISOFLEX-PU 500

The polyurethane, liquid waterproofing membrane ISOFLEX-PU 500 is applied by roller or airless spray in three layers. The first layer is applied 2 to 3 hours after application of the polyurethane primer PRIMER-PU 100 and while the surface is still slightly tacky. The second layer is applied crosswise to the first one in different color for control purpose, after 8 to 24 hours, depending on the weather conditions. After 8 to 24 hours the third layer is being applied and while the layer is still fresh silica sand (0.4-0.8mm) is broadcasted in order to create a final anti-slip surface.

ISOFLEX-PU 500 could be applied also with the addition of ACCELERATOR 5000. ACCELERATOR 5000 is a special set accelerator for ISOFLEX-PU 500 that enables its application at low temperatures or in thicker layers. It also increases the thixotropy and mechanical strength of ISOFLEX-PU 500.

Total consumption of polyurethane, liquid waterproofing membrane, ISOFLEX-PU 500: 2.3-2.5 kg/m², depending on the substrate.

After 7 days the asphalt concrete could be applied above the hardened membrane ISOFLEX PU 500.

The hardened polyurethane liquid membrane ISOFLEX-PU 500 offers an appropriate substrate for the adhesion of the asphalt concrete. Asphaltic solutions with petrol etc should be avoided.



  • ISOFLEX-PU 500 may be applied when the ambient temperature is 5ºC and rising, and the temperature of the substrate is a minimum of 3 degrees above the dew point. The maximum application temperature is approximately 35ºC. Low temperatures retard curing while high temperature accelerates curing. High values of humidity may affect the final finish of the membrane.
  • Maximum consumption of ISOFLEX-PU 500 per layer should not exceed 750 g/m². With the addition of ACCELERATOR 5000 each layer should not exceed the 1.25 kg/m².
  • Possible creeping of the asphalt concrete normally is due to the quality and characteristics of asphalt (softening point) and is not relative to the adhesion of the polyurethane membrane.
  • Consult the instructions for safe use and precautions written on the packaging.
  • Consult the technical data sheets of the products for the right application.