Concrete needs protection against carbon dioxide, chloride-ions and sulphur dioxide, the main causes of damage to concrete. The binders contained within easy-on™ Series 300 are outstanding in this connection and offer diffusion resistance in excess of 200 times greater than Silicate emulsions.

CONCRETE


Concrete products offer a number of coating challenges. The basic binding material in concrete is cement. Mixed with water, the cement will react and turn into another material that is strong and durable. To increase the strength, concrete contains stony aggregates, in a variety of different sizes.

PRE-TREATMENT


The standard of surface preparation has a direct impact on achieving a long lasting performance and is even more important than the application of the paint itself.

MATERIALS


easy-on™ Series 300 is a two component material which is water resistant when used correctly.

CORROSION


Concrete needs protection against carbon dioxide, chloride-ions and sulphur dioxide, the main causes of damage to concrete. Efflorescence and corrosion is the fungus and rot in concrete. In the same way as woodwork may be discoloured by mildew and mould, and broken down by fungus growth, a similar break-down may occur in the case of concrete. Efflorescence, regarded by many people as an esthetical phenomenon only, is a clear indication that something is wrong. Efflorescence is the fore-runner of the sneaking destroyer of concrete called corrosion.

All supporting structures of concrete are reinforced with re-bars made of steel. Steel will corrode when exposed to humidity and air (oxygen), unless exposed to a very alkaline solution (pH value of 12-13), when no corrosion will take place.

Normally, concrete is a very alkaline material, which is why steel can be used as reinforcement in concrete structures. Over a period of time, however, something happens to the concrete, a process in which the alkaline calcium hydroxide reacts with carbon dioxide from the atmosphere forming calcium carbonate:


Ca(OH)2 + CO2 = CaCO3 + H20(Water)

By this formation of CaCO3 the pH value will drop, for example the environment will become more acidic and the steel begins to corrode. Sulphur Dioxide is even more reactive and creates an even lower pH-value in the concrete. When steel corrodes, the volume is increased many times. This causes cracks and ruptures in the concrete, leading to further destruction by water penetration and a chemical weakening of the concrete.

Summing up, CO2 and SO2 penetrate the concrete. The protective alkalinity is being reduced. The carbonisation process has reached the re-bar and the steel corrodes. Corroding steel expands 4-6 times and an enormous pressure will be exerted to the surroundings causing the concrete to crack and loosen. Expanding rust forces pieces of concrete to fall off allowing the re-bar to become exposed, continue to corrode, and the strength will be reduced.

PREVENTION


By preventing water, CO2 and SO2 from getting into direct contact with the concrete, the structures may, theoretically, last forever. By simply painting the concrete with a relatively impermeable paint system, one can achieve:

  • less corrosion
  • less efflorescence
  • less frost damage
  • better filling of crevices and pores
  • better cleaning properties
  • better appearance

CONCLUSION


All paints designed for use on concrete will, to some degree, have a positive effect against concrete corrosion, but the less permeable, the better. The binders contained within easy-on™ Series 300 are outstanding in this connection and offer diffusion resistance in excess of 200 times greater than Silicate emulsions.