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Curing is the process of providing moisture to the concrete mix so that better interlocking is established. If curing is not done properly then it will cause insufficient hydration and as a result there will be capillary pores, causing cracks and shrinkage. Moreover, strength and durability will also get affected and the concrete will disintegrate and break. It also ensures to maintain a sufficient temperature of concrete at its early age. It must be implemented as soon as placement & finishing is done. Also, it must continue for a specific period for the concrete to achieve its desired strength and durability. Uniform temperature is necessary to avoid thermal shrinkage cracks, plastic shrinkage and problems like bleeding and segregation.
Why curing is done?
Some of the reasons of curing of concrete are –
Types of Curing
There are three methods of curing –
1. Method 1 – Methods that preserve mixing water in the concrete during the early hardening period. These include spraying and fogging, ponding or immersion, and saturated wet coverings. These methods facilitate cooling of concrete through evaporation that is beneficial in hot weather.
2. Method 2 – Methods that prevent the loss of water from the surface of the concrete. This can be implemented by applying plastic sheets or impervious sheets or by application of membrane forming compound.
3. Method 3 – Methods that increase the rate of gain of strength by addition of heat and moisture to the concrete. It is implemented with the help of live steam, heating coils or electrically heated pads.
Fig 1: Immersion of concrete
Courtesy: Builders Mart
Fig 2: Sprinkling on concrete
Fig 3: Wet coverings on concrete
Courtesy: Concrete Décor Magazine
Fig 4: Impervious paper on concrete
Fig 5: Plastic sheets on concrete
Courtesy: Epic projects and consulting
Fig 6: Curing membrane water based WB compound
Fig 7: Internally moist curing of concrete
Courtesy: Leca AE
Fig 8: Steam curing
Courtesy: Sika Concrete
Curing methods depend on number of factors like type of materials used, size and shape of structural members, mix proportions, strength, weather conditions and future exposure conditions. The curing period varies differently like in may take 3 weeks for lean concrete to be sued in mass concrete structures such as dams or it may take few days for rich mixes. These are normally shorter for steam curing and ranges from few hours to 3 days. However, longer curing periods are desirable. For slabs, beams, columns or small footings, the curing period should be of minimum 7 days above the temperature of 50 C. When the temperature equal to or below 50 C, then the recommendations by ACI Committee 306 must below to prevent the concrete from damaging by freezing. Also, continuous supervision is required at the site to ensure that proper curing is taking place and the hydration process is continuing.
1. Maha Cement, “The Importance of Curing Concrete”- https://www.mahacement.com/the-importance-of-curing-concrete/
2. NBM & CW, “Significance of Curing of Concrete for Durability of Structures”- https://www.nbmcw.com/tech-articles/concrete/25057-significance-of-curing-of-concrete-for-durability-of-structures.html
3. PCA, “The Difference Between Curing and Drying Concrete”- https://www.cement.org/learn/concrete-technology/concrete-construction/drying-concrete-vs-curing-concrete
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