Curing and Protection of Fresh Concrete

Curing maintains moisture and temperature in fresh concrete to achieve its designed strength and durability.
Inadequate curing causes surface cracking, dusting, reduced strength, and long-term durability problems.
Common curing methods include polythene sheeting, curing compounds, wet hessian, and water spraying.
Curing should begin as soon as the concrete surface can bear it without damage, typically within hours.
Hot weather accelerates moisture loss from exposed concrete, requiring immediate and sustained curing measures.
Cold weather slows hydration; insulating blankets and heated enclosures may be needed to maintain curing temperatures.
Curing compounds form a membrane on the surface and must be applied evenly at the specified coverage rate.
Fresh concrete must be protected from rain, frost, foot traffic, and construction loads until it has hardened.
The specified curing duration depends on cement type, ambient temperature, and structural requirements.
Quality control testing including cube testing relies on representative curing conditions being maintained.

Achieve design strength	Poorly cured concrete fails to reach its design strength, compromising structural integrity and requiring costly repairs.
Prevent cracking	Rapid moisture loss from exposed surfaces causes plastic shrinkage cracking that reduces durability and appearance.
Specification compliance	Curing is a specification requirement. Non-conformance results in rejected work, remedial measures, and programme delays.

Do

Don't

Begin curing as soon as the concrete surface can bear it without damage.
Apply curing compound evenly at the coverage rate stated on the product data sheet.
Cover exposed concrete with polythene sheeting in hot or windy weather.
Protect fresh concrete from rain, frost, and foot traffic until it has set.
Use insulating blankets in cold weather to maintain curing temperature above 5°C.
Maintain curing for the full duration specified in the design or specification.
Spray water on hessian covers regularly to keep the concrete surface moist.
Record the curing method, start time, and ambient temperature in the pour records.
Protect cube samples with the same curing conditions as the placed concrete.
Brief the pour team on the curing method and their responsibility to maintain it.

DON'T leave fresh concrete surfaces exposed to sun and wind without curing.
DON'T apply curing compound unevenly or at less than the specified coverage rate.
DON'T walk on or load fresh concrete before it has reached adequate strength.
DON'T allow rain to wash the surface of fresh concrete before it has set.
DON'T pour concrete if overnight frost is forecast without protection measures planned.
DON'T remove polythene or hessian curing covers before the specified curing period ends.
DON'T allow curing compound to contaminate surfaces that will receive bonded finishes.
DON'T assume warm weather means curing is unnecessary; heat dries surfaces faster.
DON'T neglect cube sample curing; unrepresentative results lead to false failures.
DON'T ignore plastic shrinkage cracks appearing within hours of placing concrete.

See also: Concrete Pour Safety | Concrete Cube Testing Safety

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