Proper concrete curing is essential to achieve maximum strength and durability of the finished concrete. Curing of concrete involves maintaining adequate moisture inside the concrete mix to continue the hydration process. It is one of the Concrete curing methods by using Concrete curing compounds.It is alternatives of water for concrete curing. It is designed to minimize the loss of water during concrete curing.
Curing compounds for concrete are now easily available in the market. Types of concrete curing compounds are listed below.
- Synthetic resin compound
- Acrylic compound
- Wax Compound
- Chlorinated rubber compound
Concrete curing compounds form a thin liquid membrane on the concrete surfaces and result in prevention to a certain extent of evaporation losses.Generally, they are available in two types, clear or translucent and white pigmented. The clear or translucent concrete curing compound may contain a fugitive dye to assure complete coverage of the concrete surface by visual inspection. This dye fades as the application is few hours old.
Courtesy - theconstructor.org
The following precautions are necessary when curing compounds for concrete are used:
01. Concrete curing compounds should be stirred in a container before use to make it uniform and it is easy to maintain thoroughly mixed solution. They should not sag, run off peaks, or collect in grooves. The film formed by curing compound should be tough to withstand early construction traffic without wear or tear.
02. The curing compound film must be non-yellowing and should not discolour the concrete surface, and should have good moisture-retention properties.
03. Curing compound should be applied soon after the formwork of vertical surfaces are removed or soon after final finishing of the horizontal surface is completed.
04. Curing compound should be sprayed uniformly on the concrete surface. If the coating is sprayed uniformly, the curing compound will cover nearly 3.5 to 5.0 sqm per litre but it may vary from manufacturers to manufacturers.
05. Curing compound must be preferably sprayed in two layers. The second layer must be sprayed at a right angle to the first layer. The application can be done by hand or power sprayer generally at 0.5 to 0.7 MPa (0.055 to 0.077 Kg/mm2) pressure.
06. The spray nozzle must be held about 300 to 500 mm from the surface especially during windy conditions.
06. Curing compound must attain complete coverage of the surface because even small pinholes in the membrane will increase the evaporation of moisture from the concrete.
07. Make sure that cleaning solvent is available for cleaning the spraying equipment, the nozzle and the hose whenever there is break in usage for more than half an hour.
08. Do not use concrete curing compound on the surface between hardened concrete and freshly placed concrete overlay, renderings, flooring, paints etc because it prevents bonding of any surface application which may come on the concrete surface subsequently. For example, some curing compounds may affect the adhesion of paint to concrete.
09. Continuous monitor following main two things.
- Test the surface with NDT test to verify the strength of hardened concrete.
- Always buy standard company product, as it will be impossible to repair or strengthen uncured concrete if quality curing compound is not good.