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Concrete Curing

How to avoid carbonization during concrete floor curing

Propane construction heaters produce carbon dioxide, which reacts with water to produce carbonic acid. Carbonic acide, in turn, combines with calcium hydroxide to form calcium carbonate.

This can produce powdering, or, in extreme cases, flaking of concrete surfaces. To eliminate or minimize carbonization, keep CO2 levels as low as possible during the first 24 hours (after this period CO2 enhances the strength of concrete).

This can be done in 2 ways:

  1. Taking outside air for combustion
  2. Using a pass through technique, where sufficient ventilation is provided to ensure a concentration of no more than 2.5 percent CO2. This requires extra heat, but it is still cheaper than using indirect heating.

During the critical first 24 hours, CO2 tests must be taken hourly with a Draeger unit and CO2 capsules. If CO2 levels increase beyond the 2.5 percent level, ventilation should be increased to reduce the level.