Raft Foundation – Advantages And Construction Method

What Is Raft Foundation?

Raft foundation is a type of shallow foundation, made of dense reinforced concrete slab covering the total area of the bottom of a structure.

Sometimes the slabs are used at the bottom and the beams at the top. This foundation is most suitable for constructing heavy structures on soft made ground or marshy sites having a low bearing capacity.

raft foundation

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Raft foundation is also provided in the mining area where the structure is liable to fail due to uncertain behavior. It gives an economical solution to difficult site conditions when pile foundation can not be used. This foundation sometimes is also known as mat foundation because the RCC slab covers the whole area of a structure like a mat.

Method Of Construction:

The slab for raft foundation is projected at a distance of 30 cm to 40 cm on every side of the outer walls of a structure. Thus the area of excavation becomes slightly greater than the area of the structure. The entire area is then excavated to its required depth and consolidated. When the surface becomes dry it gives a strong base on which the raft slab is established.

All the necessary precautions should be taken during the construction of RCC structures. Further construction should be started after the curing of the raft foundation.

Advantages Of Raft Foundation:

The advantages of raft foundation are as follows:

1. Raft foundation can be suitably used in difficult site conditions. It is mostly preferred for the erratic, soft, and marshy sites. It bridges the erratic deposits and reduces the differential settlement.

2. The intensity of pressure on the foundation soil is considerably decreased due to the distribution of total load over a large area.

3. The load is uniformly distributed on the entire foundation area.

raft foundation

Also Read –

Types Of Foundation Used In Construction

Types Of Footings Used In Construction





Types Of Pile Foundation

Where To Use Pile Foundation

Types Of Bridge Foundation

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3 thoughts on “Raft Foundation – Advantages And Construction Method”

  1. this type of foundation gives an economical solution to difficult site conditions…
    i like you posts they really help me in my studies

  2. I need suggest!!!
    u know if someone know about only theory of civil but he don’t know how to draught any think!
    so this guy can achieved something or not in this field on basis of only theory of civil!!!
    ????????be reply plssszs


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