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Curing methods of concrete can be broadly classified into the following categories.
1. Water curing.
2. Membrane curing.
3. Hygroscopic curing &
4. Thermal curing.
Now let us discuss one by one starting from water curing and the different types that come under all these curing methods.
1. Water curing:
This is the best method of curing since it satisfies all the standards needed to cure like absorption of heat of hydration, prevention of shrinkage, and facilitating the hydration reaction.
Different methods which come under water curing are,
a. Sprinkling:
Water is sprinkled several times a day over the concrete surface keeping them wet until the last day of the curing period. This method can be used to cure both horizontal and vertical concrete surfaces. Using a pipe with pressurized water makes the work lot easier.
Water is sprinkled several times a day over the concrete surface keeping them wet until the last day of the curing period. This method can be used to cure both horizontal and vertical concrete surfaces. Using a pipe with pressurized water makes the work lot easier.
b. Ponding:
The horizontal surface of the concrete like slab, flooring, concrete road surfaces, etc. can be cured by this method. A barrier is created on all four sides of the surface to retain water and the surface is kept flooded with water until the final curing period to gain concrete strength.
The horizontal surface of the concrete like slab, flooring, concrete road surfaces, etc. can be cured by this method. A barrier is created on all four sides of the surface to retain water and the surface is kept flooded with water until the final curing period to gain concrete strength.
c. Covering:
Certain materials like hessian cloth, gunny bags, paddy straw, etc. were used to cover the concrete surface since they have a quality to retain water in them for a longer period. They were periodically wetted to prevent the evaporation of water.
Certain materials like hessian cloth, gunny bags, paddy straw, etc. were used to cover the concrete surface since they have a quality to retain water in them for a longer period. They were periodically wetted to prevent the evaporation of water.
d. Immersing:
Precast products like pavers, r.c.c. doors & windows, r.c.c. grills, concrete cubes, etc. were cured by immersing method. These materials were kept in the water-filled tank and taken out when they achieve their final strength. This method saves labor, as no periodic inspection and daily curing are required.
Precast products like pavers, r.c.c. doors & windows, r.c.c. grills, concrete cubes, etc. were cured by immersing method. These materials were kept in the water-filled tank and taken out when they achieve their final strength. This method saves labor, as no periodic inspection and daily curing are required.
2. Membrane curing:
Here, the concrete is covered by an impervious membrane, which will effectively prevent and seal off the evaporation of water from the concrete surface. Some of the materials which are used for this method are bituminous compounds, wax emulsions, polyester films, rubber compounds, etc.
This method is adopted in places where there is an acute shortage of water. This method is not an efficient one when compared to water curing.
3. Hygroscopic curing:
In this method, hygroscopic compounds like calcium chloride are applied over the surface of the concrete. These compounds absorb the atmospheric moisture and facilitate curing by keeping them wet. Nowadays this procedure is rarely used.
4. Thermal Curing:
Concrete is subjected to heat from within or from the outside so that the curing process accelerates resulting in fast curing. The different ways of doing thermal curing are,
a. Steam curing:
Here, steam is applied to the concrete to gain high early strength by accelerating the process. The two methods are followed in doing such type of curing.
Here, steam is applied to the concrete to gain high early strength by accelerating the process. The two methods are followed in doing such type of curing.
In the first method, concrete is cured under normal atmospheric pressure by passing steam over it.
In the second method, the concrete material is placed in the enclosed chambers known as autoclaves, where the materials were treated by steam under high temperature and pressure. The strength is achieved within 24 hours, which saves time and multiplies the production capacity.
Precast concrete products like AAC blocks and CLC blocks were cured by using such processes.
b. Electrical curing:
Heat is applied to the concrete using blankets from outside or electrodes are used to provide heat from within the concrete. Due to the heat created, the concrete gets cured within a short period of time. This method is ideal for cold-weather regions where otherwise more time is spent in the curing.
Heat is applied to the concrete using blankets from outside or electrodes are used to provide heat from within the concrete. Due to the heat created, the concrete gets cured within a short period of time. This method is ideal for cold-weather regions where otherwise more time is spent in the curing.
c. Infrared or U.V. curing:
This is another method of applying heat to the concrete body. Here curing temperature is achieved through the machine which emits infrared or ultraviolet rays.
This is another method of applying heat to the concrete body. Here curing temperature is achieved through the machine which emits infrared or ultraviolet rays.
To go through the articles related to the different types (classifications) of construction materials, click here.
For a better explanation with images, you can watch the video here.
