We all know that concrete is the vital material needed for the construction of any man-made structures. Without concrete, literally, no construction of buildings, bridges, dams and other structures etc is possible. Concrete is known for its incredible compressive strength.
Normally concrete is used in constructing buildings whose foundations are built on the land but during the construction of structures like bridges, dams etc, the foundation part of the structure lies underwater, therefore in these cases, underwater construction is the only possible method.
Since the construction involves underwater, then underwater concreting can only be used. Here we briefly explain about underwater concreting and its types. Underwater concrete is a type of high-performance concrete used to construct bridges, dams and any other structure whose foundation lies in the water. Generally, a concrete type must perform well in three particular areas, then only it is termed as high-performance. Those three performance indicators are strength, workability, and service life.
How is it prepared
Underwater concrete is generally prepared as conventional concrete, but there are certain differences involved in the preparation. Even though the normal concrete has its advantages on land, in water, things are a little different. Although it will remain unaffected by the water once the concrete is mixed and set in position, it can be subjected to agitation or movement while it is in its setting phase. Due to this, the conventional concrete can be disrupted by the movement of either concrete through the water or water against the concrete. This results in the washout of cementitious materials and fine aggregate from the concrete. In order to prevent the washing out, special ́anti washout́ admixtures and placing techniques are used in the conventional concrete.
Placement of Underwater concrete
Once the underwater concrete mixture is prepared and ready, it must be placed into the water. For that purpose, there are different methods through which underwater concrete can be placed. Although, there are many methods available due to the emergence of innovative technologies, only the most widely used methods are described. These methods are:
- Tremie method
- Pump method
- Hydrovalve method
- Toggle bags method
- Bagged Concrete method
Out of these methods, the most commonly used method is Tremie method. All these methods and their working will be explained in Part-II of this blog until then stay tuned.