What is Mat Foundation? Uses, Functions, and Construction.

A raft or mat foundation is a massive continuous square or circular concrete slab that includes the complete load of the superstructure and spreads it over the entire vicinity below the constructing. It is taken into consideration as one sort of shallow basis and is useful in controlling the differential settlement.

A mat foundation spreads out beneath the footprint of the building and declines the touch stress in comparison to traditional strip or trench footing.

It is a suitable solution for low bearing potential soil, unfold footing cowl about 70% of the structure, high structure masses, smooth wallet or cavities of in the soil to unknown extent raft, and noticeably compressible soil that extends to a excellent intensity.

Functions of Mat Foundation

• It Transfers superstructure loads and spreads it over the entire area of the building.
• It reduces differential settlement of structures constructed on weak soil such as saturated clays, fine silts and loose sand.

Uses of Mat Foundation

1. It is used in construction of commercial buildings. In this case, the loads are typically large. Mat foundations are popular in areas where basements are prevalent.
2. Mat foundations are used in low-bearing soil to distribute load and ensure a stable foundation.
3. It reduces differential settlement in buildings.
4. A raft or mat foundation is used for unstable soil layers. In this case, a strip foundation would cover more than 70% of the ground beneath the structure. In some cases, particularly in mining areas, the soil layer may move.

Construction of Mat or Raft Foundations

1. Ensure uniform and flat soil by removing dirt and excavating it.
2. The foundation bed is compacted by ramming.
3. A waterproof plastic sheet is placed over the earth.
4. Pour a 7cm layer of plain cement concrete to ensure a level base for the foundation.
5. Apply reinforcement to spacers over the foundation bed. Steel mesh reinforces the structure in both directions. Two meshes are reinforced at the top and bottom of the foundation to counteract upward and downward bending forces.
6. Concrete is poured to the desired thickness, typically 200mm to 300mm for small buildings, but can be thicker for heavier loads. A minimum 50mm rebar cover should be maintained.
7. Use a suitable curing regime to ensure concrete meets the designated compression strength.

Advantages of Raft Foundation

1. It requires minimal excavation.
2. It can deal with mixed or poor ground conditions.
3. It reduces differential settlement.
4. It takes more time than other foundations.
5. This foundation is way too expensive.
6. We cannot make this foundation for a normal building.

Disadvantages of Raft Foundation

1. It takes more time than other foundations.
2. This foundation is way too expensive.
3. We cannot make this foundation for a normal building.
4. We cannot repair this foundation.
5. A mat foundation must be treated specifically for point loads.
6. If the edges are not properly treated, they erode.

FAQ about Mat Foundation