Choosing the right type of foundation for the building is the main task during construction. Much depends on it: how long the building will last, whether it will be safe for people, what maximum external load the general structure will withstand, and whether the building can withstand during an earthquake. The selection of the correct type of foundation slab device depends on a large number of factors, such as the composition of the soil on which the foundation will be located, environmental temperature conditions, goals and methods of operation. Therefore, this matter should be approached with particular care.
What are the types of foundation (basic)?
During the construction process, several types of foundation can be used . They are divided into a number of categories that differ from each other in the way they occur in the ground and the materials used in the construction of the foundation.
According to the type of emphasis on the ground, the foundation is divided into three groups:
- columnar foundation ;
- strip foundation;
- foundation in the form of a monolithic plate;
The foundation is also divided into several types, depending on the materials chosen for its construction:
- rubble base;
- brick foundation;
- foundation of concrete.
Columnar, or, as it is also called, pile foundation
The main principle of building this type of foundation is to use piles to transfer the load of the building's weight to the ground. A pile is a long cylinder made of durable material (usually concrete, wooden structures are used in some cases) that is pushed into the ground to serve as a stable support for any structures built on it.
When do you use the pile type of foundation?
It is used on weak soils or for the construction of high-rise buildings that transmit a large level of load to the base of the building. Due to unstable soil or its heavy weight, a building can gradually sink to the ground, therefore, a point load transfer is necessary. Usually an unstable topsoil cannot support the weight of the structure, so the total load should bypass this level of the surface and be transferred to a layer more resistant to external influences of the rock or rocky foundation, which is much lower than the topsoil.
The pile foundation is used to hold very heavy weight, for example, the weight of high-rise structures, railway and road bridges, water tanks. This type of foundation is able to withstand higher loads than other types of similar structures.
There are two main types of pile structures (based on structural behavior), each of which works according to its own specific principle.
Conical type piles
In piles of this design, the lower end rests on a layer of particularly strong soil or rock. Thus, the total load of the building weight is transferred through several layers of unstable soil to a stronger layer. The key principle of its ability to hold weight is that the lowest part of the cone rests on a surface that is at the intersection of a less stable layer and a reliable type of soil that is already able to support the load.
Friction piles
Friction piles work on a different principle. The pile carries the load of the building to the ground over its entire height due to lateral friction. To imagine how this works, just look at regular ice cream on a stick. This stick is also a kind of analogue of a friction pile, since due to constant lateral friction it is able to hold a rather large weight compared to its weight.
Monolithic foundation slab
The foundation of this type is used during the construction of buildings, the base of which is located at a shallow depth. In most cases, it is used for the construction of small structures: garages and cottages made of wooden components and foam concrete blocks.
The appearance and internal structure of the foundation slab is very simple - this design consists of one solid foundation block made of concrete or reinforced concrete. This type of foundation is referred to as a floating type foundation. The thickness of the slab for the foundation is from twenty to forty centimeters. In some cases, not one, but several combined blocks are used, for example, when laying roads. However, for the construction of buildings on ordinary, stable soil, it is better to use a monolithic design.
Advantages of a monolithic base plate:
- Ease of installation of the foundation and low cost of installation work.
- The process of mounting the plate can be entrusted to workers with a low level of skill.
- Reliable overall integrity of the building built on this platform. The device of a monolithic base plate allows you to avoid deformations from temperature extremes and, accordingly, the appearance of cracks both in the foundation itself and in the walls of the building.
- Material saving. The upper surface of the slab can be used as the floor of the first floor of the building.
- Reduction of time and money spent on the initial excavation work. By itself, the device of the foundation plate allows you to save on digging a pit. It will simply not be needed.
The device of a monolithic reinforced concrete foundation slab has several disadvantages:
- Not suitable for the construction of buildings with a large load on the ground.
- The increase in costs during the construction of buildings of a large area due to the use of a large number of consumables.
Appearance and internal structure of a monolithic plate
The photos presented in the article allow you to get acquainted with how the foundation of the structure is formed. The device of foundation reinforced concrete slabs is quite simple. At first, a compacted sand cushion is laid on the soil leveled before installation. Crushed stone is poured onto it in order to improve waterproofing. Then concrete is poured onto the prepared base. If it is necessary to improve the resistance of the future base of the building to loads, then before pouring concrete, the total area of the foundation is additionally reinforced.
Foundation concreting
In itself, the installation of a monolithic foundation slab implies the mandatory use of concreting during the creation of the foundation. Without it, it will not be possible to create a strong structure and ensure the integrity of the building. To perform the operation, you will need special equipment and equipment.
During concreting, several operations are performed sequentially:
- Concrete mixture is delivered to the place of foundation pouring.
- The mixture is poured onto prepared fittings and in special wooden sections.
- The concrete is laid with a deep vibrator.
- At the end of the process, the laid concrete is compacted and leveled.
Strip or flat foundation
Now let's look at the construction of foundation reinforced concrete flat slabs. What are its features? What is the technology for building this type of foundation slab? We also study its characteristics.
A flat reinforced concrete slab is a subspecies of the usual monolithic foundation, resting on the soil, which extends under the entire building, thereby supporting the transfer of the weight of the structure to the ground. The arrangement of foundation flat concrete slabs implies their use on floating or weak soil surfaces, since such a foundation distributes the weight of the building as much as possible over the entire area of the foundation foundation, and not on its individual sections. It has high technical parameters: concrete of the best quality is necessarily used for manufacturing. The material used for the construction of reinforced concrete slabs sets quickly, is durable and reliable in use.
The strip foundation is most often used for the construction of basements, since with the help of such plates the side blocks of the base of the building are also erected. Due to the nature of its use, concrete is additionally reinforced.
Use of screeds in the construction of the foundation
It's time to study the types and arrangement of the expansion joint in the foundation plate. As already mentioned, in some cases, the foundation can consist of separate blocks. Creating the base of a building from several parts is beneficial in certain circumstances: for example, it is advisable in areas with high seismic activity or in regions with sharp changes in temperature. These negative natural and weather disasters can adversely affect the foundation and damage its integrity. In the event that several blocks of the foundation are used, only one of them will be damaged, and the rest will continue to fulfill their function of maintaining the weight of the entire building.
To strengthen the reliability of the composite foundation, special expansion joints are used. They are also used as compensators that can reduce the negative loads on the foundation that occur during temperature extremes or during earthquakes. There are five groups of expansion joints. The device of concrete flat foundation slabs of strip type implies their mandatory use:
- Shrink seam. It is used to evenly distribute the load on a monolithic slab or on a strip type foundation, thanks to it the control of foundation deformations during its shrinkage is improved.
- Sedimentary seam. Ensures the integrity of a building erected on an unstable type of soil.
- Temperature expansion joint. It is necessary when building foundations of buildings in regions with sharp changes in temperature or in areas where very high or low temperature of air and soil is possible.
- Seismic expansion joint. It protects the building from seismic shocks of small power.
- Combined version of the expansion joint. This version of the seam combines the qualities of all or several types of expansion joints.
Choosing the foundation for a residential building
During the construction of a residential building, whether it is a small country house or a building with several floors, you can use any of the above foundation structures. The choice of a specific type of foundation depends on several factors: this is the type of soil, the total weight of the building and the personal wishes of the owner of the future building.
If you plan to build a house without a basement, then it is better to use a monolithic slab or a structure of several monolithic blocks. In this case, the device of the foundation slab under the house will completely depend on the quality of the soil and environmental conditions. If the building is located in an area with sharp temperature changes or in a region with an unstable type of soil, it is advisable to use a structure of several plates fastened with expansion joints. Those who are interested in the presence of a basement should attend to the construction of the foundation of the tape type. Also, this type of foundation for construction will be rational when building a house from light materials: wood and foam concrete.
Before you begin to lay the foundation, it is advisable to familiarize yourself with all of the above types. And only then, taking into account all the features of the building, land and land, start building.