Mat Foundation | Mat Slab Foundation | Types of Mat Foundation

Mat Foundation

Mat Foundation

The mat foundation is a thick reinforced concrete slab supporting arrangements of columns or walls in a row or rows and transmitting the loads to the soil.

This foundation is made up of a continuous rectangular or round concrete slab covering a large area. Which is designed to carry the full load of the building’s superstructure.

This foundation is made of a thick reinforced concrete slab. This foundation is made up of rows or rows. Which carries the load of the column or wall.

This foundation is suitable for use as a foundation to support storage tanks, industrial equipment, silos, chimneys, and various tower structures.

Mat Slab Foundation

Mat foundation is also commonly known as the raft foundation in construction. It is used where soil load-bearing capacity is weak. This foundation is a kind of wide continuous slab type foundation.

This type of foundation is used as the foundation of the whole building. Because it is loaded with all the columns and beams of the structure. It is usually designed to withstand the load from the structural member of the building when the ground is weak.

All loads from the superstructure are distributed to the ground by the mat foundation. Generally, a mat foundation is a continuous thick slab laid on the ground, on which all the columns and beams of the building structure are made.

Also Read : Caisson Foundation | Use of Caisson Foundation | Type of Caisson Foundation | Advantages & Disdvantagesof Caisson Foundation

Functions of Mat Foundation

  1. This foundation covers the entire area of the building footprint to transfer superstructure loads.
  2. The main function of this foundation is to provide stability for constructions built on weak soil. Because there is a risk of differential settlement in this soil.

Mat Foundation Uses

A proper foundation for a building structure is very important for any building.  Raft Foundation Uses are:

  1. This foundation is typically used where individual footings overlap or close to the walls of the structure.
  2. Its cost is slightly lower than the Deep Foundation’s cost.
  3. This foundation is used to make foundations when the bearing capacity of the soil is very low.
  4. This foundation is adopted in case the spread footings cover more than 50% or 50% of the base area due to heavy load in the heavy column.

Also Read : What Is Monolithic Slab? | Application of Monolithic Slab | How to Prepare Monolithic Slab Foundation? | Advantages & Disadvantagesof Monolithic Slab

Types of Mat Foundation

Different types of foundations are used in construction depending on the condition of the soil and the load applied to the foundation. Its types are described as follows,

1. Flat Plate Mat Foundation

Flat Plate Mat Foundation

A flat plate raft is used for foundations of small and lightweight structures, it is advisable to use a this foundation when the soil is not compressed.

Reinforcement bars (cage) are provided in both the top and bottom of the this foundation.

This foundation usually has a minimum of 12 inches thick RCC slab.

2. Plate Thickened Under Columns Mat Foundation

Plate Thickened Under Columns

In this type of foundation, when there is a heavy load on the column and load-bearing walls, the thickness of this foundation under the columns and walls of the slab is increased.

In this type of foundation, extra reinforcement is placed to resist diagonal shear and negative reinforcement.

Also Read : What Is Floating Slab? | Purpose of Floating Slab | Construction of Floating Slab | Advantage & Disadvantage of Floating Slab

3. Two-Way Slab and Beam Mat Foundation

Two-Way Slab and Beam Mat Foundation

In this type of foundation, all the columns are placed in a perpendicular direction according to the structural design of the building. And each column is connected to the beam in the slab foundation.

This type of foundation is used in the construction of a building when the distance between the columns is greater. This results in uneven load on the column of such a building.

4. Piled Mat Foundation

Piled Mat Foundation

In this type of foundation, the foundation is supported by piles in the ground.

The construction of these bases is used for high compacted soils. Where the water table in the ground is high for the formation of the foundations of buildings.

In this type of foundation, piles are used as required to increase the load-carrying capacity of the soil for the foundation of the structure of the building.

Also Read : What Is Pitched Roof? | Types of Pitched Roof | Advantage & Disadvantage of Pitched Roof

5. Rigid Frame Mat Foundation

Rigid Frame Mat Foundation

A rigid frame mat foundation is suitable for designing the foundation of a building when excessive load is applied to the column.

When the depth of the foundation of the building is more than 90 cm, a rigid frame mat foundation is used.

6. Cellular Mat Foundation

Cellular Mat Foundation

The structures of cellular mat foundation are box type. In this type of foundation, the walls of each box act as beams.

In this type of foundation, the walls of the box are attached to the slab above and below. This type of mat foundation is suitable for loose soils.

This type of foundation is known as box type foundation.

Also Read : What Is Concrete Frame? | What Is Precast Concrete Frames? | The Components of Concrete Framed Structures | Advantage & Disadvantage of Concrete Framed Structure

Construction of Mat Foundations

The construction process of a mat foundation is very important for every building as this type of foundation requires extra care.

Some of the procedures for mat foundation are described below.

1. Soil Excavation

Excavation of the soil is important for the mat foundation. Because it has to provide a wide and plain surface for the foundation. The depth of excavation for mat foundation is based on the bearing capacity of the soil and the structural requirements of the building.

2. Waterproofing

A waterproof sheet for mat foundation is usually laid on the ground thus making it waterproof. This protects the foundation from moisture.

3. Mat Foundation 

The reinforcements are usually provided in the mat foundation to resist the bending moment and to resist the shear force.

This type of mat foundation is given reinforcement at the top and bottom.

Extra shear is provided for the reinforcement column. Support is provided to the shear link design requirement.

Also Read : What Is a Dead Load? | What Is Live Load? | Environmental Load | Difference Between Dead Load Vs Live Load

Advantage of Mat Foundation

  1. This foundation can be designed as a shallow foundation. It is very important in poor soil conditions.
  2. The load of the building can be transferred over a wide area through the mat foundation.
  3. It shows good resistance during natural disasters like floods and does not move in such conditions.
  4. This foundation has the ability to handle heavier loads than other types of bases.
  5. This foundation can be designed as a shallow base. So less has to be dug for the foundation of the building.

Also Read : What Is Folded Plate? | Folded Plate Structures | Folded Plate Staircase | Advantages & Disadvantages of Folded Plate Structures

Disadvantage of Mat Foundation

  1. Since the mat foundation is able to cover a large area, it requires a large amount of steel and concrete.
  2. Mat foundation is expensive compared to other foundations.
  3. The use of mat foundation is not suitable for home construction. It does not require a large area for foundation.
  4. In the case of concentrated loads, special measurement is required in mat foundation.
  5. More shuttering materials are required for the mat foundation.
  6. The mat base requires expert labor for compaction during concreting.

Also Read : What Is Cedar Wood? | Uses of Cedarwood | Type of Cedarwood | Advantage & Disadvantageof Cedarwood


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Frequently Asked Questions (FAQ)

Mat Foundation

The raft foundation, also known as the mat slab foundation, is a continuous slab of clay that transfers the entire load of the building to the ground, supporting the building and transferring its weight to the ground.

Types of Mat Foundation

  1. Flat Plate Mat Foundation
  2. Plate Thickened Under Columns
  3. Two-Way Slab and Beam
  4. Rigid Frame Mat Foundation
  5. Piled Mat Foundation
  6. Cellular Mat Foundation

Raft Foundation Construction

Some of the procedures for mat foundation are described below.

  1. Soil Excavation
  2. Waterproofing
  3. Mat Foundation

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