Newly placed concrete must be cured for a set period of time to allow the concrete to achieve its potential strength, water tightness and durability, and to minimize cracking. To cure, concrete must be kept damp and within a limited temperature range. Wall forms should be left in place for at least three days to retain moisture for proper curing, and longer if possible. After the forms have been removed, the curing should continue at least another day if the concrete temperature is kept above 21°C (70°F), and for another three days if the concrete temperature is kept between 10°C (50°F) and 21°C (70°F).
Maintain moist conditions by placing a soaker hose around the top of the wall and allowing water to run down the wall. When water curing is not practical, spray-on curing compounds that inhibit evaporation can be used. If a dampproofing compound is applied to the wall, curing can progress without the need for spraying. In hot weather, concrete should be protected from rapid drying. Wood forms should be sprinkled with water while they are in place to deter concrete drying. In freezing weather, freshly placed concrete footings should be protected with a thick layer of straw or other insulating material.
For walls, it may be necessary to insulate the forms or to erect an enclosure and use space heating appliances. Cure concrete slab-on-grade by spraying with water, covering with burlap kept continuously moist, polyethylene sheeting or other means to prevent moisture loss. Allowing concrete to cure properly is an important step in the construction process. Attention to this step will help avoid costly problems.
Source : Canada Mortgage and Housing Corporation (CMHC)