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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WHAT IS EARTHING??? WHY IT IS DONE???WHAT IS GOOD EARTHING???


WHAT IS EARTHING AND WHY IT IS DONE

 Earthing is an electrode embedded in the soil to provide path to the leakage current.

 Earthing is provided to :

a) To save Human life from shock and also probability of death.

b) To Protect Large Buildings from Atmospheric Lightening.

c) To protect all machines and to maintain line voltage.

 What is a Good Earthing

• A Good Earthing is that earthing which gives very low resistance to the flow of heavy current.

• The Potential at earth is Zero

 TYPES OF EARTHING 

1. Pipe Earthing




2. Plate Earthing




HOW DO WE GET A SHOCK

Human Body is a conductor. When a Live Wire touches the human body, current completes its path through body and earth resulting in a shock. The muscular functions of the body are paralyzed due to the current action on the nervous system causing breathing problems, severe burns, and resulting in death.

PRECAUTIONS TO BE TAKEN TO PREVENT ELECTRIC SHOCK :

• Care in handling all electrical apparatus and equipment.
• Never use appliances which are faulty.
• Replace immediately broken switches and plugs etc.
• All the metallic parts of the appliances are properly earthed.
• Never put a bare wire in a plug. Always use a Plug Top.
• Always use proper insulated Hand Tools.
• Use correct rating of Fuses.

Electrical Safety demands a Good Earthing

Hence always keep earth connections in good conditions..............///

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