What is Prefabrication ? Advantages and Disadvantages ?

What is prefabrication?

Prefabrication is a method which the components are cast and cured at any manufacturing site and transported to the actual site then erected according to plan.

Why Prefabrication is needed?

• Prefabrication is a modern construction technique that is growing in popularity. Prefabrication enables time and cost savings, quality control, and an eco-friendly construction process.
• Prefabricated sections are cast and cured in large quantity at the factory site and then transported to various construction sites.
• This procedure works in any poor weather conditions and also reduces time and material wastage at the site.
  
• This technique allows the erection of structures in less time.

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Prefabrication building components and their connections :

1. COLUMN: 

A column is a vertical member carrying the beam and floor load and transfers to the foundation.

It is a compression member and therefore The columns to be connected properly.

The main principle involved in making column connections proper is through continuity.

2. BEAM:

Beams are horizontal members which take loads from the slab and transfers to the column.

So these have to be connected at columns and explained below,

Methods of connecting beams and columns are

• A pre-cast haunch is fixed to the column and a dowel or stud helps to connect the beam and column
• A projecting metal corbel is fixed to the column and the beam is bolted to the corbel.
• Column and beam reinforcement, generally in the form of hooks, are left exposed.
• The two members are hooked together and covered with concrete to complete the joint

3. SLAB:

Here, this component resists on the beams and transfers the load directly on the beam.

• They are laid in a grid pattern.
• These units are cast in moulds.
• The saving achieved is not much.
• Time consumption for construction is less                      

Prefabrication is done in two stages,

1.Manufacturing at factory condition 

2.Erection of components at the required location.

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Steps Involved in Prefabrication :

CASTING:

Precast components are cast with controlled cement concrete for required shape and size.

Here the Reinforcement is placed before Pouring any concrete and The vibrator is used to vibrate concrete,

this removes any honeycombing inside the components.

CURING:

After 24 hours of casting, the casted components are released from the moulds and shifted to the curing tanks.

For certain special components where high strength is required are steam cured for faster gaining of strength.

This curing will be done for at least 3 days and further it will be cured after erecting these components at the site.

TRANSPORTATION AND ERECTION:

After 3 day period the components are transported to the site with heavy trucks and erection will be done using cranes with skilled labour force.

Advantages and disadvantages of Pre-fabrication

Advantages :

• Saving in cost, material, time & manpower.
• Shuttering and scaffolding is not necessary.
• Installation of building finishes can be done immediately.
• Independent of weather condition.
• Components produced at close supervision .so quality is good
• Clean and dry work at site.
• Possibility of alterations and reuse
• Correct shape and dimensions and sharp edges are maintained.
• Very thin sections can be entirely precast with accuracy.

Disadvantages :

• Handling and transportation may cause breakages of members so care has to be taken.
• It is a non monolithic construction.
• Placement of members plays a major role
• High transport cost
• Need of erection equipment
• Skilled labour and supervision is required.

conclusion :

Advantages are more predominant than the disadvantages but due to Indian psychological barrier,

This Modern technique haven’t penetrated into our roots. But there is a hope that future desires and situations can definitely convince our mentality.

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