Introduction to 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.
The mat 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.
The mat foundation is made of a thick reinforced concrete slab. The mat foundation is made up of rows or rows. Which carries the load of the column or wall.
The mat foundation is suitable for use as a foundation to support storage tanks, industrial equipment, silos, chimneys, and various tower structures.
What Is Mat Foundation?
The mat foundation is also commonly known as the raft foundation in construction. Mat foundation is used where soil load-bearing capacity is weak. The mate 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. The mat foundation 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.
Functions of Mat Foundation
- This foundation covers the entire area of the building footprint to transfer superstructure loads.
- The main function of the mat foundation is to provide stability for constructions built on weak soil. Because there is a risk of differential settlement in this soil.
What Is Mat Foundation Used For?
A proper foundation for a building structure is very important for any building. The key points of the situation in which mate foundation should be used are as follows,
- The mat foundation is less than the deep foundation cost.
- The mat foundation is made in case the individual footings overlap as they are close to the walls of the structure.
- Mat foundation is adopted in case the spread footings cover 50% or more than 50% of the base area due to heavy loads in the heavy column.
- Mat foundation is adopted for building foundation when the bearing capacity of the land is very low.
Types of Mat Foundation
Different types of mat 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,
- Flat Plate Mat
- Plate Thickened Under Columns
- Two-Way Slab and Beam
- Rigid Frame Mat
- Piled Mat
- Cellular Mat Foundation
1. Flat Plate Mat Foundation
A flat plate raft is used for foundations of small and lightweight structures, it is advisable to use a mat foundation when the soil is not compressed.
Reinforcement bars (cage) are provided in both the top and bottom of the mat foundation.
This foundation usually has a minimum of 12 inches thick RCC slab.
2. Plate Thickened Under Columns Mat Foundation
In this type of foundation, when there is a heavy load on the column and load-bearing walls, the thickness of the mat foundation under the columns and walls of the slab is increased.
In this type of mat foundation, extra reinforcement is placed to resist diagonal shear and negative reinforcement.
3. Two-Way Slab and Beam Mat Foundation
In this type of mat 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
In this type of mat 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.
5. 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
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 mat 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 mat foundation is known as box type foundation.
Construction of Mat Foundations
The construction process of 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.
- Soil Excavation for Mat Foundation.
- Waterproofing for Mat Foundation.
- Mat Foundation Reinforcement
1. Soil Excavation for Mat Foundation
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 for Mat Foundation
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 for Reinforcement
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.
Advantage of Mat Foundation
- The mat foundation can be designed as a shallow foundation. The mat foundation is very important in poor soil conditions.
- The load of the building can be transferred over a wide area through the mat foundation.
- The mat foundation shows good resistance during natural disasters like floods and does not slip in such conditions.
- Mat foundation has the ability to handle heavier loads than other types of bases.
- The mat foundation can be designed as a shallow base. So less has to be dug for the foundation of the building.
Disadvantage of Mat Foundation
- Since the mat foundation is able to cover a large area, it requires a large amount of steel and concrete.
- Mat foundation is expensive compared to other foundations.
- The use of mat foundation is not suitable for home construction. It does not require a large area for foundation.
- In the case of concentrated loads, special measurement is required in mat foundation.
- More shuttering materials are required for the mat foundation.
- The mat base requires expert labor for compaction during concreting.