About Mat Foundation

2. Welcome to
Presentation
on
Mat
Foundation

3. Contents
1. Introduction
2. Foundation
3. Types of Foundation
4. Types of Deep Foundation
5. Types of Shallow Foundation
6. Mat Foundation
7. Types of Mat Foundation
8. Criteria of Mat Foundation
9. Mat Foundation Should Not be Used
10. Mat Settlement
11. Different Methods of Design
12. Casting of Mat Foundation
13. Construction Procedure
14. Different Real Views
15. Conclusion
16. Reference

4. Introduction
All engineered structures resisting on
the earth, including earth fills, dam
(both earth and concrete), buildings
and bridges consists of two parts, the
upper or superstructure and lower or
foundation. The foundation is an
interfacing element between the
superstructure and underlying soil or
rock in the case of earth fills or earth
dams there is no clear line of
demarcation between the
“superstructure” and foundation.

5. Foundation
The lowest part of the
structure which provides
a base for the
superstructure proper is
known as foundation

6. Foundatio
n

7. Types of
Foundation
1. Deep Foundation
2. Shallow foundation

8. Types of Deep
Foundation
a. Piles
b. Cofferdams
c. Caissons

9. Types of
Shallow
Foundation
a. Spread footing
b. Grillage footing
c. Eccentrically loaded footing
d. Combined footing
e. Mat or raft foundation

10. Mat foundation
The word mat is used to denote a
sub structure that transmits its
loads to the soil by means of
continues slab that covers the
entire area of the bottom of the
structure.

11. Mat foundation

12. Types of Mat
Foundation

13. Flat plate

14. Flat plate thickened under column

15. Two way beam and column

16. Flat plate with pedestals

17. Cellular
Construction

18. Basement Walls As Rigid
Frame

19. Criteria of Mat Foundation
1. A requirement for a high degree of structural
continuity and ability to resist sub grade
movement.
2. Expansive sub grade at the site.
3. Structures with uniform loads and respectively
spaced columns and walls.
4, Structure with deformation sensitive
architectural finishes.

20. Mat Foundation Should not be
used
1. Continuity and level of performance is not
required.
2. There are large open functional areas without
interior loaded columns.
3. There are widely spaced andor vary heavily
loaded column andor wall loads.
4. More constructible andor economical
foundation types will produce equal or better
performance.

21. Mat settlements
Mat foundations are commonly used where
settlements may be a problem as where a site
contains erratic deposits or lenses of compressible
materials, suspended boulders, etc. The settlement
tends to be controlled via:
1. Lower soil contact pressure
2. Displaced volume of soil
3. Bridging effects due to
a. Mat rigidity
b. Superstructure rigidity contribution to
the mat

22. Different methods of
design
1. Approximate Method
2. Finite-Difference Methods for Mat
Foundations
3. Finite-Element Methods for Mat Foundations

23. Casting of mat
foundation
1. Construction material –
a. Binding material
b. Fine aggregate
c. Coarse aggregate
2. Quality of materials
a. Binding materials- Cement- Ordinary port
land cement.
b. Fine aggregate- Sand- 2.8 FM
c. Coarse aggregate- Stone chips
d. Water- Drinking quality
3. Mixing procedure-
By machine

24. Construction
procedure
Steps 1- The mat slab generally projects for a
distance of 30cm to 45cm, on all the sides of the
outer walls of the structure and as such the area
of excavation is slightly more than the area of
structure itself.
Steps 2-The excavation is made to the required
depth and the entire excavated area is well
consolidated by sand. This surface, when dry,
provides the base upon which the mat slab is
laid.

25. Steps 3-A brick layer is placed upper
the sand layer if it required getting
more strength.
Steps 4-Reinforcement is placed upper
these layer to construct mat slab.
Steps 5-Then the concrete has cast.

31. Conclusion
Mat foundation is the most suitable foundation under
conditions when the soil at the site or proposed
structure is erratic, soft and marshy having lot of
compressible lenses. Mat foundation bridges the
erratic deposits and eliminates the possibility of
differential settlement. Overall settlement of structure
is reduced as the total load of the structure is
distributed over large area and thus intensity of
pressure on the foundation soil is reduced in
minimum. Total settlement in case of sandy soil is
limited to 65mm and that in case of clayey soils
125mm. Distribution of load on entire area of
foundation is uniform.

32. Reference
1.Foundation Analysis and design
-Joseph E. Bowels
2. Reinforced concrete manual & Building
plan
-Khan & Rahman
3. Foundation Design
- Wayne C. Teng
4. Building Construction
- Sushil Kumar
5. http://www.google.com

33. Thanks To
All