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The selection of curing methods for structural concrete elements is governed by the size and shape of concrete members, type of concrete used, such as normal concrete or high-strength concrete, economy, material availability, labor force, in-situ versus plant concrete production, weather, and aesthetics.
Curing methods are generally classified into three major groups: water retention methods, water addition methods, and temperature control methods.
The selection of a suitable curing method would help the structure to gain the required strength efficiently. A certain curing technique is suitable for a specific type of concrete member; for instance, ponding is suitable for flat surface and plastic sheets are appropriate for non-windy locations.
It is better to know the different aspects of concrete curing methods and select the most suitable curing technique for the building to avoid the undesired effects of improper curing.
How to Select the Right Curing Method for Structural Concrete Elements?
Table-1 presents different methods of curing concrete and selection criteria.
Table-2 shows different types of curing techniques and their applicability. Sometimes, the type of the structure controls the curing method selection for instance ponding is categorically not suitable for vertical elements.
Table-1: Curing Methods and their Selection Criteria
|Curing methods||Techniques||Selection criteria|
|Water addition methods||Ponding |
Other wetted absorbent materials
|1. Useful for concrete with a low w/c ratio of less than 0.40. |
2. It is the only method of curing that prevents internal desiccations of low w/c ratio concrete
3. Suitable for concrete made with expansive cement
4. The application is simple but creates a mess.
5. Acceptance criteria and quality control are easy.
6. Thermal shock can be a problem when evaporation rates are high, which may cause cracking. The temperature gradient should not be greater than 13 degrees over 5 cm concrete depth.
7. Good option for structures constructed in hot weather conditions
8. Costly in arid regions
9. Sprinkling is not suitable for windy regions
|Temperature control methods||Live steam, heating coils, electrically heated forms or pads.||1. It is complicated since several variables are involved|
2. Caution on rapid evaporative cooling
3. Control temperature of fresh concrete
|Water retention methods||Impervious paper Plastic sheeting Polyethylene sheet Pigmented sheet Membrane-forming curing compounds||1. Suitable for concrete with a water-cement ratio of greater than 0.40.|
2. Curing compounds are not suitable due to cost, availability, and bonding issues.
3. Non-windy conditions
4. Practical for small areas
5. Acceptance testing and quality control are simple.
6. Direct contact between the sheet and concrete should be prevented to avoid mottled pattern.
Table- 2: Curing Techniques and Their Applications
|Ponding and Immersion||Small jobs |
Flat surfaces like pavements and floors
Concrete test specimens
Not suitable for vertical concrete members
|Fogging and Sprinkling||Ground slabs |
|Wet Coverings||Vertical concrete members |
Horizontal concrete members
|Impervious Paper||It is an efficient technique of curing horizontal surfaces and structural concrete of relatively simple shapes.|
|Plastic Sheets||White film is suitable for curing exterior concrete during hot weather since it reflects light, whereas black film is appropriate for cold weather or interior locations.|
|Membrane-Forming Curing Compounds||Practical and most widely used method for curing freshly placed concrete and extending curing of concrete after removal of forms or after initial moist curing.|
|Internal Moist Curing||Cement-rich concrete|
|Forms Left in Place||It is suitable for beams and columns, especially in hot weather conditions.|
|Steam Curing||Precast concrete members|
|Electrical, Oil, Microwave, and Infrared Curing||Precast Concrete Member|
1. Water addition method
2. Water retention method
3. Temperature control method
1. Size and shape of the concrete element.
4. Cast-in-place versus precast concrete
5. Type of concrete
6. Material availability
7. Labor force
8. Aesthetics of concrete structure
If concrete is not cured adequately, its strength and durability are reduced, and consequently, the safety of the structure may be endangered.
Curing is responsible for the strength development and durability of concrete. That is why the curing process should be conducted properly.