What is the purpose of keeping tremie pipe’s tip immersed in freshly-placed concrete for about 1m in underwater concreting?

  What is the purpose of keeping tremie pipe’s tip immersed in freshly-placed concrete for about 1m in underwater concreting? The size of tremie pipe is about 300mm with sections having flange couplings fitted with gasket to prevent water leakage. The tremie pipe should be closed initially to prevent water from entering the pipe. It should be designed with sufficient thickness and weight so that it would not be buoyant when empty inside water. The placement of tremie concrete is commenced by putting the closed pipe underwater to the location for concreting, followed by partial filling of tremie pipe with concrete. In order to have tremie concrete flowed out of the pipe, it is necessary to fill the pipe with concrete of sufficient height to overcome the water pressure and frictional head. After that the tremie pipe is raised about 150mm to allow concrete to flow out. To enhance sufficient bonding, each succeeding layer of concrete should be placed before the preceding layer has reached
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HOW ELECTRICITY GENERATED ?? WHAT IS TRANSFORMER??

HOW ELECTRICITY IS GENERATED

Power Generation:

The bulk electricity is generated in generating station/power plants. The main machine which generates electricity is Generator. A generator is a machine which converts mechanical energy into electrical energy.

Types of power generating stations:

(1) Hydro-power generation.
(2) Steam power generation
(3) Gas turbine power plant.
(4) Diesel power station
(5) Nuclear power station.

Main Components of Power Generation:

(1) Prime mover: This converts energy from some form to mechanical energy. This is normally coupled to the Alternator for rotating.
(2) Alternator: This converts Mechanical energy into Electrical energy. The output of alternator is delivered to the busbars through transformers, breakers and later transmitted through transmission lines for distribution.


WHAT IS A TRANSFORMER

• The transformer may be defined as static piece (No rotating part) of apparatus which converts Electrical Power from one circuit to the other circuits at the same frequency. It can increase or decrease the voltage with corresponding increase or decrease of current. It works on the principle of Mutual Induction.

• Transformer has two windings :

Primary winding to which the supply is fed and Secondary winding from which supply is taken.

• Transformers can be a step up ( To step up the Voltage) or step down ( To step down the Voltage).

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