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Improper curing is often the weakest link in concrete construction. Even after placing the concrete, the durability and performance of a concrete structure are highly influenced and created during a specific time period. Curing practices are most important. Therefore, knowledge of the curing of concrete, the types of concrete curing, and suitable methods of concrete curing is essential for high-quality construction, particularly when employing reinforced concrete with steel supplied by reputable TMT manufacturers, like Sree Metaliks.
What Is Concrete Curing?
Curing of concrete refers to the process of controlling the environment of concrete for a prescribed period and maintaining moisture, temperature, and time to allow for proper hydration of cement. Hydration of cement, a very critical process, is a reaction between cement and water, taking place for a very long time (days and even weeks) after pouring. If concrete is cured improperly, the moisture in the concrete will rapidly evaporate. This leads to a condition described as a loss of concrete durability, developing cracking, and the concrete will shrink.
Once the concrete has set and is strong enough, the concrete curing process is underway and must continue until the concrete has reached the desired strength. Adequate curing of concrete allows the concrete to achieve its design strength, increases durability, stabilises concrete against harmful environmental conditions, and preserves the condition of the tied reinforcement, TMT bars, embedded in the concrete.
Concrete Curing in Construction and Its Relevance
There is no question as to the relevance of concrete curing. Curing does the following:
- It increases compressive and flexural strength.
- It lowers the chances of surface cracking and shrinkage.
- It protects the concrete against abrasion.
- It protects the concrete against severe weather conditions and chemical attacks.
- It ensures the reinforced concrete structure will be durable over time.
- It protects the concrete steel reinforcement from rust.
With the use of quality TMT and reinforced materials, even with the use of quality materials, with improper curing, there will be a range of 40–50% loss in potential strength.
Concrete Curing Process in Total: Which Factors Are Influencing This Process
There are several factors:
- Temperature and Humidity of the Average Environment
- Cement Type and Mixture Design
- Water-cement Ratio
- External Conditions (sun, wind, rain)
- Size and Shape of Concrete Member
These factors and the nature of the structure should guide you to the onset of the correct concrete curing methods to be used.
Types of Concrete Curing
Concerning the types of concrete curing, we can distinguish:
(1) Water-based curing
(2) Membrane curing
(3) Heat curing
(4) Miscellaneous and other advanced curing methods.
Each of the techniques has a specific functionality and best serves a given construction scenario.
1. Water Curing Methods
Water curing techniques are the most traditional and commonly used method. Water curing entails a continuous moisture supply over the concrete surface.
1. The Ponding Method
Ponding is creating small embankments around horizontal concrete slabs. They are filled with water. This method helps to maintain moisture.
Pros:
- Effective for slabs and other pavements construction.
- Uniform hydration is guaranteed.
- The method is simple and cheap.
Cons:
- The method is ineffective for vertical and inclined surfaces.
- Needs a lot of water.
2. Fogging or Sprinkling Method
In this method, water is periodically sprayed over the surface of the concrete. The spraying is done using a hose or a sprinkler system.
Advantages:
- Ideal for extensive areas
- Straightforward in application
Limitations:
- Needs continuous supervision
- Possibility of inconsistent hardening of concrete in case of insufficient water
2. Wet Covering (Hessian or Gunny Bags)
Concrete surfaces are covered with wet burlap, hessian, or gunny bags that are kept moist at all times.
Advantages:
- Suitable for vertical elements like columns, beams, etc.
- Slows down moisture escape
Limitations:
- Needs more workers
- Needs moist covering
2. Membrane Curing Methods
The membrane curing method stops the concrete from drying surface with a coverage.
1. Plastic Sheets
Low-permeability sheets are put over the concrete to minimise loss through evaporation.
Advantages:
- Saves water
- Useful in very dry or windy environments
Limitations:
- Edges need to be properly sealed
- May affect the appearance of the surface negatively
2. Curing Compounds
A liquid that forms a membrane is sprayed on the concrete surface to retain moisture within the concrete.
Pros:
- Saves money and manpower.
- Perfect for bigger tasks, such as highways and large-scale industrial flooring.
Cons:
- Unsuitable for areas where more layers of concrete and/or plastering are needed.
- Requires uniformity.
3. Heat-Based Concrete Curing Methods
Heating concrete speeds up the curing process.
1. Steam Curing
Concrete curing is done using warm, moist air.
Pros:
- Accelerates early strength development.
- Great for industrial precast concrete elements.
Cons:
- Expensive and requires steam curing tech.
2. Hot Water Curing
Hastens the hydration process of concrete by submerging concrete products in hot water.
Pros:
- Great for industrial precast concrete elements.
Cons:
- Expensive and is limited only to precast concrete products.
4. Electric and Infrared Curing
These new methods of curing concrete use infrared heat or electric resistance to heat the concrete from the inside.
Pros:
- Great for use in cold weather.
- Great for extreme temperature control.
Cons:
- Very expensive.
- Specialised tech in electric and infrared curing is needed.
5. Natural Curing
Natural curing happens in ambient conditions, with no need for extra water or coverings.
Advantages:
- Cost-free
Disadvantages:
- Extremely unreliable
- Not suitable for structural concrete
6. Self-Curing Concrete (Internal Curing)
Self-curing concrete contains lightweight aggregates or water-releasing chemical admixtures to cure the moisture that is lost during the hydration process.
Advantages:
- Removes the need for external curing
- Good for high-performing concrete
- Increases durability
Disadvantages:
- Increased material costs
- Needs detailed mix design
Time Frame for Concrete Curing:
The curing duration will depend on the type of cement used and the environmental conditions:
- Ordinary Portland Cement (OPC): Minimum of 7 days
- Blended cement (PPC/PSC): Minimum of 10 to 14 days
- Structural concrete elements: Strength is typically assessed at 28 days, though curing duration may be shorter depending on design and environmental conditions
Correct curing time helps to keep water and reinforcement from being depleted from the mix. Hydration is the process of curing and relies on moisture from surrounding materials. A good reinforcement is always provided by a certified TMT manufacturer.
Concrete Curing and Reinforced Concrete Structures
Concrete curing is particularly sensitive when it comes to reinforced concrete structures. Inadequate curing will leave the steel reinforcement elements exposed to moisture/oxygen, which can cause early corrosion. The combination of good-quality TMT bars from a reputable TMT manufacturer with good curing really enhances structural performance and service life.
Common Mistakes in Concrete Curing
Common mistakes related to curing include the following:
- Curing started too late
- Curing for too short a time
- Lack of uniform water distribution
- Forgetting about curing in high or low temperatures
- Too much faith in natural curing
These mistakes should be avoided to appreciate the value of concrete curing fully.
Best Practices for Effective Concrete Curing
- Start curing as soon as the concrete is set
- Choose curing techniques according to the weather and the type of structure
- Ensure there is a water supply for the duration of the cure
- Ensure no part of the curing concrete gets too hot or too cold
- Stick to the instructions for curing given by the design's structural engineer
Also Read : Different Types of Concrete Mixing Ratio
Conclusion
The curing of concrete, the proper choice of types of concrete curing, and adherence to the required concrete curing process are the basis of efficient construction. Effective curing allows the concrete to reach its full strength and durability, to withstand the effects of the environment, and for structures to have their intended functionality. Along with premium components and the best TMT Manufacturer reinforcement, efficient concrete curing methods are paramount to safety in long-lasting and affordable construction.
For more information, please reach out to us at: Sales@sreemetaliks.com