What is Curing Compound and its Properties?
Curing Compound is a liquid solution sprayed on a freshly laid concrete surface to reduce the evaporation of water from the concrete by creating favorable conditions for the formation of hardened concrete. It is preferable to use when there is no sufficient water around.
Concrete must set at a particular temperature and moisture level. Because cement is a hydraulic substance, water provides it strength. Therefore, it might be dangerous to have either too much or not enough water present when concrete is setting. Curing chemicals are needed to produce such moisture precision levels and optimum temperature rates.
whereas, proper safety measures are taken to maintain the required moisture content in concrete.
A curing compound should be placed as soon as bleed water stops gathering on the pavement surface. Tensile tensions arise when bleed water accumulates between the pavement surface and the membrane, causing pinholes in the membrane if the compound is applied too quickly.
The higher evaporation rate produced by the pinholes increases the risk of shrinkage cracking. If the curing compound is applied too late, after excessive evaporation has occurred, shrinkage cracks might appear.
Curing compounds that produce membranes are often made up of a wax or resin that has been emulsified in water or dissolved in a solution. After applying the compound to the pavement surface, the water or solvent ingredient evaporates, leaving the wax or resin to create a barrier across the pavement’s surface. This membrane helps in the retaining of moisture in the concrete.
Concrete pavements are also cured with emulsified linseed oil cure/sealer chemicals. The oil slows evaporation by closing the pores in the concrete, while the sealant protects against degradation caused by freeze-thaw cycles and deicing chemicals during the critical time of early strength development.
Additionally, the properties to determine the quality of concrete curing by compound includes water retention, reflectance, drying period, long term setting, and non volatile matter.
Types of Compound
- Chlorinated Rubber Compound – When applied, it forms a thick surface film. It securely seals the concrete and also closes the minute pores in the concrete. However, the film cannot be seen for a long period of time.
- Acrylic Compound – It is composed of acrylic acid polymers. It has the ability to stick to the succeeding plaster. If plastering is required, there is no need to wash the surface of acrylic with hot water.
- Synthetic Resin Compound – This compound creates a membrane that will seal the concrete. The membrane can be removed by washing with hot water if plastering is required.
- Wax Compound – This compound resembles resin compounds in their characteristics. Over time, the wax membrane will become less effective.
- Reduces the loss of water from the concrete surfaces.
- Helps to minimize the shrinkage cracks
- Maintains uniform moisture content over a larger surface area pavement.
- Expensive compared to water
In all concrete-related operations, curing compounds are utilized to limit the evaporation of water and harden the concrete. As per ASTM C 309, testing of concrete curing compounds is permissible. Concrete curing compound tests and specifications are provided by ASTM C 309.
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