2. Raft Foundation
- Can support a number of columns & walls
- Consists of reinforced concrete under the whole of a building
- Cast on the surface of the ground
- Lowers the contact pressure
4. Advantages of Raft Foundations
- Economic
- requires little excavation
- can cope with mixed or poor ground condition
Disadvantages of Raft Foundations
- requires specific treatment for point loads
- edge erosion occurs if not treated properly
- less effective
6. Pad Foundation
- shallow foundations
- Suitable for most soil
- square , rectangular or sometimes circular in shape
- used to support ground beams
( The thickness of the slab must be sufficient to
ensure distribution of the load )
7. Types of Pad Foundations
Plain Concrete
- economic option
Reinforced Concrete
- enables relatively wide but shallow foundations
Continuous Pad
- exists when pads and the columns they
support are fairly closely spaced
8. Combined pad foundations
- adopted close to a site boundary to
enable the balancing effect of an internal
column to be incorporated.
Pad and ground beam
- smaller isolated pads are connected by
ground beams to provide structural
rigidity.
9. Suitability of Pad Foundations?
- Loads imposed are relatively light
- High bearing capacity of the surface soils
Cost
- More expensive than trench and strip footing
10. Advantages of Pad Foundations
- Economic
- Convenient
-Less bearing capacity and weak
-Uneconomical if the water table is high
-Chance of scouring
Disadvantages of Pad Foundations
