The concrete sub-base is essential for creating sturdy and long-lasting foundations. This layer, which is frequently disregarded, is crucial to guaranteeing the longevity and stability of any structure. However, what is a concrete sub-base precisely, and why is it so crucial?
A layer of material directly below the main concrete slab of a foundation is called a concrete sub-base. Crushed stone or compacted gravel usually make up this layer. The sub-base’smainfunction is to give the concrete slab a level, stable surface to rest on. Inadequate preparation of the sub-base can cause uneven settling of the foundation, which over time can result in cracks and other structural problems.
The uniform distribution of the structure’s weight across the ground is one of the concrete sub-base’sprimaryroles. This aids in preventing an excessive amount of weight from being carried by one area, which could lead to shifting or sinking. A suitable sub-base also aids in drainage, keeping water from collecting beneath the foundation and possibly causing damage.
To sum up, the construction of a foundation requires the use of a concrete sub-base. It facilitates weight distribution, offers stability, and helps with drainage. Builders can construct sturdy, long-lasting foundations that withstand the test of time by making sure the sub-base is solid.
- Why do you need to install a concrete sub-base?
- Types of simple concrete sub-bases
- Crushed stone
- Sand
- Concrete pad
- Installation of the concrete base
- Video on the topic
- WHY DO YOU NEED CONCRETE PREPARATION FOR THE FOUNDATION
- Subconcrete. Concrete preparation for the foundation. Norms and rules for subconcrete.
- Foundation construction. Subconcrete. What is it and why?
Why do you need to install a concrete sub-base?
The concrete sub-base serves several beneficial purposes, including:
- Creates a waterproofing layer. Thanks to this, during the process of pouring the foundation, the liquid cement mortar will not leak. In addition, the moisture in the screed will be distributed evenly and the base will not crack when drying.
- Allows you to create a flat surface for the rough concrete base. Thanks to this, the consumption of cement-sand mortar is reduced.
- Protects the foundation from groundwater.
- Redistributes the pressure exerted by the soil and above-ground parts of the building.
- Allows you to produce higher-quality reinforcement.
- Excludes shrinkage of the building.
Such a shock-absorbing layer also considerably increases the overall structure’s strength and durability. It is easier for a foundation built on a concrete sub-base to "survive" the winter.
It is clear from everything above why the brist is required, so let’s move on to the different types of these plates.
Types of simple concrete sub-bases
There are various kinds of slabs for foundations:
Crushed stone
Since crushed stone is less expensive than cement composition, this kind of "preparation" is thought to be more cost-effective. The layer of crushed stone needs to be at least 20 cm thick. Thorough compaction is a prerequisite for installing the concrete sub-base (preferably with vibratory ramming equipment).
When discussing the drawbacks of "preparation," one of the technologies that is deemed untrustworthy is the process of laying crushed stone sub-base beneath the foundation. The truth is that such a substrate is insufficiently rigid, so top-notch work on laying the foundation on such a base will not be done. But, if you don’t intend to construct a multistory structure, a utility block or restroom will be perfectly fine with such a concrete sub-base.
The easiest base to install is as follows:
- Prepare the work surface and lay crushed stone on it.
- Level it with shovels.
- Tamp and compact the cushion over the entire surface.
- Apply a layer of bitumen to the resulting concrete sub-base to obtain good waterproofing. If you want to save money, you can use roofing felt or polyethylene instead of bitumen, but these materials have lower waterproofing properties.
Sand
Sand "preparation" enables the optimal load redistribution on the foundation base. It is advised to lay these cushions in the spring and fall when the soil is changing. The monolith will not be harmed by moisture because the lower portion of the foundation will be above groundwater level because of the sand layer beneath it. For this reason, locations with problematic soil are where sand concrete sub-bases are most frequently installed.
Installing such a layer requires the following:
- Remove the soil layer.
- Fill it with river sand with a fraction of at least 1.5 cm.
- Using a building level, level the pad along the entire perimeter.
- Tamp the "preparation".
Practical! The type of soil, the presence of nearby buildings, seismicity, and the current loads must all be considered when determining the required thickness of the concrete sub-base and choosing the required type of interlayer. In-depth specifications and computations are outlined in SP 50-101-2004, SP 63.13330.2012, and SNiP 2.02.01-83.
Pads made of sand and crushed stone are not very sturdy and are not appropriate for all types of buildings. Of course, a concrete slab should be chosen first when creating the most dependable foundation possible for a residential structure.
Concrete pad
Slab and strip foundations are the ideal applications for this kind of foundation, but its installation calls for significant financial outlays. It is a fact that stronger bases are needed when installing such fundamental bases because a heavy reinforcing frame consisting of rigid steel rods is installed.
Prior to beginning the foundation installation, it is important to consider the following advice:
- For the installation of the concrete sub-base, use "lean concrete" of classes from B 3.5 to B 7.5 (M 50, 75, 100). There is no point in using stronger cement, besides, it will cost several times more.
- To obtain a strong "preparation", it is enough to lay a concrete pad 10 cm thick (provided that groundwater does not prevail on the site).
- Before laying the concrete mixture, it is necessary to pour a thin layer of sand or crushed stone onto the bottom of the pit or trench.
- If a reinforcing frame is not used when installing a concrete pad, then the optimal thickness of the base will be 15-20 cm.
- Thanks to the reinforcement of the concrete sub-base, the above-ground part of the building will be located on a reliable foundation. Metal rods with a cross-section of 8 mm are used for the armored belt. The rods are installed vertically and must protrude above the surface by about 25-30 cm. In this case, the thickness of the "preparation" can be reduced by 6-10 cm.
A layer of material placed beneath the main concrete slab of a foundation serves as a concrete sub-base, providing a level, stable surface that supports the entire structure. It facilitates even weight distribution throughout the building, keeps the foundation from moving, and helps with drainage to lower the possibility of water damage. A concrete sub-base ensures a level and sturdy foundation, which is essential for any building project’s longevity and durability.
Installation of the concrete base
Assume for the moment that you want to construct a home on a plot of land that has a lot of loose soil and a high groundwater table. In order to accomplish this, you must finish the following steps:
- Determine the highest point of groundwater – it is better to make the "preparation" exactly up to this level. Some people install the "preparation" so that it protrudes beyond the underground structure by 10 cm.
- Level and compact the soil.
- Pour coarse sand onto the bottom of the pit, spread it over the surface and compact it thoroughly. For a better effect, you can also lay a layer of crushed stone.
- Lay roofing felt or polyethylene on top of the sand.
- Lay a reinforcing frame with 60 x 60 cm cells.
- Install guides, it will be more convenient to level the liquid mixture along them.
- Mix cement, crushed stone, sand and water until a homogeneous thick mass is obtained.
- Pour concrete mortar and level it along the beacons using a rule.
- After the base has hardened, treat the surface with bitumen.
Practical! It is advised to consider the communication holes when laying raw concrete in order to avoid using costly drilling equipment after the monolith has hardened.
Question | Answer |
What is a concrete sub-base for a foundation? | A concrete sub-base is a layer of material placed below the main concrete slab. It provides a stable and even surface for the foundation to rest on. |
What is it for? | The sub-base supports the foundation, helps distribute loads evenly, and prevents the slab from settling or shifting over time. It also aids in drainage and prevents water from accumulating under the slab. |
A foundation’s concrete sub-base is an essential part of creating sturdy, long-lasting buildings. It keeps the main foundation stable and uniformly distributed by acting as its supporting structure. The sub-base helps to prevent settling and shifting, which over time can result in cracks and structural damage by offering a level and sturdy surface.
One cannot stress the significance of a concrete sub-base that has been properly prepared. It lessens the effects of soil movement and variations in moisture content by acting as a buffer between the soil and the foundation. In addition to helping with load distribution, this layer of concrete distributes the building’s weight more evenly across the ground. By doing this, the foundation’s and the building’s overall lifespan are increased.
A concrete sub-base can also help with drainage around the foundation. In order to stop water from building up around the foundation, which can lead to erosion and weaken the structure, proper drainage is crucial. Through improved water flow away from the building, the sub-base contributes to the long-term stability of the foundation.
In conclusion, building a sturdy and long-lasting foundation requires the use of a concrete sub-base. It helps with efficient drainage, stabilizes the area, and guards against damage caused by shifting soil. The foundation and eventually the entire building will endure if time and money are invested in a high-quality sub-base.