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Concrete Pipe and Vessels

waterproofing concrete pipe and vessels

Liquid EPDM Rubber is a very effective and easy one coat application for waterproofing concrete pipes and for a concrete sealer, particularly flat concrete roofs. Many of our customers throughout the Caribbean have tried product after product to waterproof concrete but nothing held up to the harsh saltwater and extreme temperatures like the epdm rubber roof. Some of the hotels in particular did not know a rubber coating for concrete existed. For concrete waterproofing applications it is important to note that freshly poured concrete may take up to a month to fully dry out. You never want to apply either the ProFlex Primer or Liquid Rubber unless the concrete is perfectly dry. Non troweled concrete will be rougher and have a surface that is more porous than one that was trowelled. Applying Liquid Rubber to a porous surface produces a high density of small craters in the cured product. Liquid Rubber during the cure process will actually penetrates into pores the result is a crater on the surface. We recommend first coating the concrete with the ProFlex primer available on our website. Liquid Rubber can then be applied over the ProFlex Primer once it has dried. A single coat of Liquid Rubber (EPDM rubber) is preferred to multiple coats.

We do NOT recommend the following as a preventative measure to avoid surface craters:

  • Water-based acrylic elastomeric roof coating (primer or base-coat version)
  • Solvent-based neoprene product due to the rigid temp and humidity requirements. The choice of water- or solvent-based product should be based on temperature and humidity conditions. For water-based products, relative humidity should be less than 70% and temperature 60 degrees or higher. Solvent-based products should be used at low temperatures and high relative humidity.

EPDM rubber was not available many years ago so liquid neoprene was the product of choice for waterproofing concrete and protecting concrete against both fresh and salt water. All of the neoprene products available are simple solvent solutions or water-based emulsions, their downfall is their low volume solid's percentages and low molecular weights. These limitations forced contractors and applications to put down multiple coats. Top-coating with other polymers was needed to prevent ultraviolet degradation and thus significantly increasing both labor and material costs. With the development of Liquid EPDM Rubber the industry could take advantage of a rubber coating for concrete with a high-solids product which was two part and whereby curing took place through a two-component chemical reaction. In addition, the product was less reliant upon environment factors allowing it to polymerize at ambient temperatures of 55 F, (13 C) and higher. Due to the high volume solid's percentage the can be applied at a 30 mil dry film (.76 mm) and can be achieved in a single application. When fully cured the membrane results in a high-molecular-weight film with protective and performance properties far exceeding those of neoprene films.

EPDM Liquid Rubber can withstand boiling water or submerged water indefinitely and is both UV and ozone stable. By increasing the flash point the product also achieves a higher degree of safety and allows it to be stored at higher temps vs. liquid neoprene. Since Liquid EPDM Rubber is non-polar it advantages over neoprene in saltwater environments, and is a highly resistant to catholic disbandment. Liquid Rubber is also highly resistant to acids, up to 50% concentration, ketone solvents, alcohols, polar compounds, salts, alkalis, and water.

Sulfuric Acid OK up to 50% concentration up to 158 deg F
Nitric Acid OK up to 50% concentration up to 70 deg F
Sodium Dichromate 11% OK up to 70 deg F
Phosphoric Acid 50% OK up to 140 deg F
Trichloroethylene 98% OK up to 70 deg F
Sodium Hydroxide 50% OK up to 176 deg F
Potassium Hydroxide 10% OK up to 200 deg F
Potassium Cyanide 25% OK up to 140 deg F
Silver Cyanide 25% OK up to 140 deg F
Nickel Chloride 50% OK up to 176 deg F

The above are guidelines used to start with. Any applications should be tested thoroughly before putting anything in service.

Advantage of Liquid EPDM Rubber

  • One-coat application.
  • UV and ozone stability.
  • Higher flash point (105 F, 40 C).
  • Storage stability at higher temperatures .
  • Can be used in extreme environments.
Liquid EPDM Liquid Neoprene
Product description Two-component, ambient-temperature cure One-component solution or emulsion
Solids content(by volume) 60-65% less than 30%
Flash point 105 F (40 C) 50 F (10 C)
(solvent solution)
Tensile strength 600-800 psi (42-46 kg/cm) 1,600 psi (112 Kg/cm)
Elongation 150 - 200% 450%
Temp. tolerance range -60 to 300 F
-76 to 149 C
-40 to 200 F
-40 to 93 C
Max dry film per coat 30 mils
.76 mm
4-6 mils
.1 to .15 mm
Ultraviolet stability Excellent Recommended top
Water resistance
fresh water
sea water

excellent to 275 F (135 C)
excellent to 180 F (82 C)
very good to 200 F (93 C)

excellent to 212 F (100 C)
excellent to 70 F (10 C)
Oil resistance Poor Very good
Hydrogen sulfide
(wet) resistance
Very good Very good
Coverage 960 sq.ft/gal/mil
8.57 sq.m/l/mm
417 sq.ft/gal/mil
3.7 sq.m/l/mm
Specific gravity 1.05  
Volatile organic
333 gr/l 600-610 gr/l

Coating Cast Concrete

Concrete that has not been  trowel finished will have a surface that is more porous   than one that has been trowelled. When Liquid Rubber is applied directly to such a porous surface, it will produce a high density of small craters in the resulting membrane. This is caused by the fact that Liquid Rubber actually penetrates into the pores, leaving a crater on the surface. The following  procedure is recommended to prevent formation of surface craters:

1) Apply a light coat of one of the following products to seal the surface:

       a.) Water-based acrylic elastomeric coating (primer or base-coat version).

        b.) Solvent-based chlorinated rubber or Hypalon product.

        c.) Solvent-based neoprene product.

The choice of water-  or solvent-based product should be based on temperature and  humidity conditions. For water-based products, relative humidity should be less than 70% and temperature 60 degrees or higher. Solvent-based products should be used  at low temperatures and high relative humidity.

2) Liquid Rubber may be applied when primer application is sufficiently dry. Water-based products should be allowed to dry thoroughly, as any surface moisture will interfere with  the adhesion of the rubber. A single coat of Liquid Rubber is preferable to multiple coats.

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