Concrete Shrinkage is a major problem in construction. Even after paying good attention during the casting of concrete shrinkage happened.
Here civil experience comes with a guide on why and how to prevent this Shrinkage of Concrete so read and share with friends if you gain valuable solutions.
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What is Shrinkage?
Everyone is friendlier with the deformations due to loads on structural elements, a concrete member has two other types of deforestation known as shrinkage and creep
While the hydration process of cement concrete takes place, the volume of cement paste decreased due to water/moisture loss in concrete which is known as shrinkage
Change in concrete volume is one of the most detrimental properties of concrete mortar, which highly affect the long term strength and durability of concrete structure building
Microcracks are developed in the concrete due to shrinkage
Shrinkage is responsible for the development of a crack in wall, floor, pavement, etc
Shrinkage is an inherent property of concrete. It can’t be prevented but its magnitude definitely can be reduced
The following four types of shrinkage strains are recognized.
- Plastic Shrinkage
- Drying Shrinkage
- Autogenous Shrinkage
- Carbonation Shrinkage
What is Plastic Shrinkage?
Cement undergoes a volumetric contraction whose quantity is nearly one percent of the absolute volume of dry cement. This kind of shrinkage is known as plastic shrinkage
Water loss from any factors like absorption by aggregate or evaporation from the concrete surface or subgrade is believed to be the reason for plastic shrinkage and loss of water results in the reduction of volume
In the case of pavements and floors, where the large surface is come in direct contact to warm sun or drying wind, the surface of concrete dries extremely fast resulting in plastic shrinkage
In the case of a high water/cement ratio of concrete, a large quantity of water accumulate and bleeds at the surface. As this surface water dries out, shrinkage cracks develop on the surface of the concrete
Causes of Plastic Shrinkage
Richer concrete also undergoes greater plastic shrinkage.
The list of main causes of plastic shrinkage is as following:
- High w/c ratio
- Wrong concrete mix design
- Rapid drying
- Unintended vibration
- Yielding of formwork
- Greater bleeding
Prevention of plastic shrinkage
- Plastic Shrinkage can be reduced by decreasing water loss from concrete. This can be obtained by covering the concrete surface with help of polyethylene sheets immediately after finishing the operation or by working at night
- A small quantity of aluminum powder also may be added to offset the effect of plastic shrinkage
- Revibrate the concrete in a controlled manner
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How many types of shrinkage?
1. Plastic Shrinkage, 2. Drying Shrinkage, 3. Autogenous Shrinkage, 4. Carbonation Shrinkage
What are the main Causes of Plastic Shrinkage?
1. High w/c ratio, 2. , 3. rong concrete mix design, 4. Rapid drying, 5. Unintended vibration, 6. Yielding of formwork, 7. Greater bleeding
What is Shrinkage?
Cement undergoes a volumetric contraction whose quantity is nearly one percent of the absolute volume of dry cement. This kind of shrinkage is known as plastic shrinkage
