Design

Strengthening foundations by placing them under existing walls. Tips for strengthening foundations

Often, owners of private houses are faced with the problem of foundation destruction. Most often this concerns old log or timber buildings. But sometimes the foundation of a new house also needs strengthening if the construction did not follow technology and take into account natural factors, for example, how deep the soil freezes in the area. In some cases, the foundation is destroyed if any objects are built near the house. And finally, the foundation requires strengthening if it is planned to add additional rooms or add floors to an already finished building. If this is neglected, then an increase in the mass of the building can lead to subsidence, distortion of entrance and window structures, the formation of cracks in the foundation and even complete destruction.

Reasons for partial destruction of the foundation

The foundation is the platform on which the structure is based. It distributes the mass of the building over the entire area and reduces the specific pressure on the soil. The performance and durability of the structure depend on its condition, since it is the base that bears the entire load from the higher structures.

Deep cracks in the foundation indicate incipient destruction

But during the operation of the building, the foundation is often subject to partial destruction. This may be due to the following reasons:

the location of the house on sloping terrain, in an earthquake-resistant area or next to a railway;
incorrectly compiled project;
errors at the stage of calculating the planned load;
non-compliance with construction technologies during the construction of the platform;
use of low-quality building materials;
improper arrangement of waterproofing;
reduction in the quality characteristics of the base;
natural phenomena - flooding, oversaturation of the soil with moisture, freezing of the soil;
human economic activity - improper operation of the house, for example, lack of seasonal heating, construction or laying of communications in close proximity to the foundation, repair or completion of the house.

Since at the initial stage of construction it is not always possible to accurately predict what load and natural factors the foundation will be subjected to, you will subsequently have to resort to strengthening it. Strengthening the foundation ensures the reliability and safety of operation of a private home, since it is country households that are most susceptible to the effects of natural factors. If you ignore the problem, you may have to completely change the foundation, and this costs a lot of money.

Before starting work to strengthen the foundation, it is necessary to conduct a thorough analysis of the reasons that caused its partial destruction. As a rule, professionals with special equipment are invited for this. They evaluate the factors causing foundation deformation and make recommendations to eliminate or minimize them.

Preparing to strengthen the foundation

Before strengthening the foundation, its external and internal inspection is carried out. During an external inspection, the following parameters are determined:

dimensions of the building;
condition of supporting structures;
presence of cracks and bevels.

During underground research the following indicators are determined:

platform design and dimensions;
strength properties of the material used;
depth of its laying.

Before you begin work on strengthening the foundation, you need to make sure that its shrinkage is complete. Usually it lasts at least a month. To understand that shrinkage has ended, gypsum beacons are installed across the identified cracks. Their condition will determine when to begin strengthening the foundation.

At the final stage of preparation for strengthening, the platform is unloaded. It can be complete or partial. An important factor is to avoid distortions that will have a negative impact during foundation restoration.

To further strengthen the foundation, the building is raised with jacks

Partial unloading of the house platform is carried out using wooden or metal supports and struts.

Install support pads in the basement, 2 m away from the wall.
Place a support beam on top.
Secure the posts.
Then connect them to the ceiling with a beam, and then to the support beam using wedges.

To completely unload the platform, steel frame beams are installed.

Under a row of masonry, in which the bricks are laid with short edges to the wall, punch grooves on both sides, keeping a distance of 2 m between them.
Place the frame beams in them and secure with 25mm bolts.
Using overlays, weld the joints of the beams, and fill the gaps from the wall to the beam with sand-cement mortar.
Punch holes in the lower part of the walls, keeping a distance between them of no more than 3 m, insert beams into the holes.
Place the cross beams on the support pads on either side of the wall.

Foundation strengthening methods

In modern construction, various methods of strengthening the foundation are used, due to the rapid development of the building materials market:

widening of the sole;
piles;
reinforced concrete pad;
replacing the base;
reinforcing belt;
reinforced concrete jacket;
cementation;
low tides;
laying new foundations;
clips;
shotcrete.

Various methods are used to strengthen the foundation

Each of the listed methods has both advantages and disadvantages. Let's look at the most popular technologies.

Sole widening

In practice, home owners most often resort to the classic, proven method of strengthening the foundation - the method of widening the base. The sole is a reinforced concrete pad on which the foundation rests. This method is the simplest, most reliable and relatively inexpensive. Several people with certain skills can handle the job.

An additional foundation is laid around the house, acting as an auxiliary support.
The sole along the entire perimeter of the structure is fixed at several pre-marked base points, the number of which depends on the size of the building and the degree of destruction of the main foundation. Typically the distance between points is 2.5–3 m.
Excavation is carried out on the sides and under the foundation.
A reinforcement screed is laid under the foundation and filled evenly with mortar.
Using a concrete vibrator, air bubbles are removed.
The side walls of the sole rise to the base by 15 cm.

The method of strengthening the foundation by widening the sole is the simplest, most reliable and relatively inexpensive

Strengthening the foundation with piles

There are many types of piles that can be used to strengthen the foundation.

Bored injection piles

You can add additional strength to the structure using drilled injection piles. Recently, this technique has enjoyed considerable popularity. But due to the use of innovative technologies, expensive materials, drilling equipment and the involvement of specialists, this method is considered quite expensive.

The essence of the technology is as follows:

After the solution dries, a new foundation of pile structures is formed, which in strength and reliability resembles the monolith on which the structure is based.

You can add additional strength to the structure using drilled injection piles

Micropiles

In some cases micropiles are used. Their diameter is 150–300 mm. During the drilling process, you can fill the wells with solution. This method involves the use of drill rods. Remaining inside the pile, they provide more reliable strengthening of the foundation.

With the help of micropiles you can strengthen not only the foundation, but also the soil

Video: strengthening the foundation with micropiles

Indentation piles

To transfer loads to hard, deep soils, indented piles are used. They are installed using special equipment. Beams mounted into the base ensure good connection between the foundation and piles.

Video: strengthening the foundation with indented piles

The method of strengthening the foundation with external piles is used when the groundwater level is high. The foundation is placed on piles. The connecting link between the piles and the foundation is a reinforced concrete beam passed through the foundation.

The foundation is placed on piles

Metal tubular piles

Installation of metal tubular piles is carried out on both sides of the platform. For this, a welding method is used using special equipment. To install the piles, a reinforced concrete frame is mounted and connected to beams supported by jacks.

Metal piles are connected by a reinforced concrete beam

Pouring reinforced concrete pad

The advantages of strengthening the platform by pouring a reinforced concrete pad are:

reduced pressure on the soil due to the large base area;
additional soil insulation. This prevents frost heaving, which is considered the most common cause of foundation failure.

The disadvantages of the technology include the inability to fill the entire foundation, but only in sections of no more than 2 m, and the need to observe the drying time of each section before pouring the next one. Therefore, this method is used to strengthen one of the corners of the foundation or in the event that the time and cost of pouring the foundation around is not important.

The reinforced concrete pad reduces the load on the ground and allows it to be insulated

Pouring the pillow under the foundation occurs in several stages:

The area to be repaired is dug up from the outside and inside of the building. At the same time, the blind area and floor are removed, the earth around the base is dug out in the form of two trenches with a length of 3.0 m to 3.5 m and a depth of ¾ of the depth of the foundation.
The condition of the foundation is assessed for the presence of cracks and damaged areas.
If the foundation is in order, a hole is dug for the cushion, up to 2 m long and 0.4–0.5 m deep relative to the foundation. The bottom of the pit must be level.
Geotextiles are placed in the hole, sand is poured in a layer of 3–5 cm and a 10 cm layer of crushed stone with a fraction of 30–40 mm is poured.
To level the surface, clean sand is poured over the crushed stone, and then a 5-centimeter layer of foam is placed.
A reinforcing structure is laid on top and formwork is installed.
The base is poured with concrete and compacted using a vibrator.
The formwork is removed after 2 days.
You can begin repairing the next section no earlier than in 25–28 days.

It is important that the concrete contains as little water as possible. The optimal proportion of water to concrete is 1:4. But too thick concrete is difficult to pour into a trench, so it can be diluted with a plasticizer sold in hardware stores.

The height of the finished reinforced concrete pad must be at least 10 cm of the foundation section being repaired. This will strengthen the base and reduce pressure on the ground.

In winter, it is not recommended to repair the foundation by pouring a concrete pad. If there are still dug trenches, protect them from frost heaving: cover them with earth and cover them with foam plastic.

Video: strengthening the foundation by pouring a concrete pad

Replacing the base

If collapse or destruction of the platform occurs in the area of the base, this part must be replaced. It is easiest to replace under a wooden structure, since it weighs less than stone or brick.

The easiest way to replace the base is under a wooden building

Under a structure made of stone or brick, the base is replaced in parts no longer than 1 m with intervals between sections of at least 3 m. To carry out the work you will need:

fittings;
cement;
sand;
crushed stone;
plasticizer;
concrete mixer;
chain saw for concrete to cut out the necessary sections of the base;
perforator;
welding machine for fastening reinforcing elements.

How to replace the base yourself

Video: replacing the base with raising the house

Filling the reinforcing belt

If the platform is covered with cracks, but their number does not increase over time, then repairs are carried out by pouring a reinforcing belt. This prevents further destruction of the base and protects it from deformation at low temperatures, but its strength increases slightly. The reinforcing belt can be poured both around the entire perimeter and along one wall.

First of all, the foundation is excavated from the outside of the building. The outer part of the foundation should be completely free of soil, but you should not dig deeper than the sand or crushed stone cushion. The optimal ditch width is 0.8–1.0 m.
The outer part of the foundation must be completely free of soil
Then it is necessary to compact the soil near the foundation using manual tamping and pour a layer of crushed stone of the 30–50 mm fraction, 10–15 cm thick. The crushed stone is also compacted. A thin layer of sand is poured over it to hide the sharp edges.
Dense foam plastic 5 cm thick should be laid on top of the sand and covered with a tarpaulin to protect the material from sparks during the welding process.
Next, you need to drill holes in the foundation with a diameter of 18–25 mm at a distance of 60–90 cm and drive pieces of reinforcement into them that will serve as anchors. The trimmings should protrude from the wall by 15–30 cm.
Weld external and internal meshes to them, made of reinforcement 10–14 mm thick, which should deviate from the base by 5–7 cm. The meshes are connected to each other using pieces of reinforcement.
Reinforcing mesh is connected by reinforcement
At the bottom of the belt, an additional reinforcing mesh is placed for the pillow, 25–35 cm thick and equal in size to the width of the ditch. The cushion reduces the load on the ground without the need to dig up the foundation.
After creating the reinforcing mesh, remove the tarpaulin from the foam and install the formwork. Concrete is poured in two stages. After filling the pillow, you should wait 2 days and then start filling the belt.
Pouring concrete is carried out in two stages
After 2 days, you can remove the formwork, and after another 3–5 days, fill the ditch with earth.

Pouring reinforced concrete jacket

A common way to strengthen the foundation is to pour a reinforced concrete jacket.

The foundation for pouring the concrete jacket is dug taking into account the length of the fills no more than 3 m

This method is quite simple. A person with the slightest skills in construction can fill a reinforced concrete jacket alone. To do this you will need the following materials:

concrete grade M400;
reinforcement for tying the frame with a thickness of 16–18 mm.

Work order

Cementation method

The cementation method is also called injection. This is explained by the introduction of hollow tubes into the cracks of the platform. As a rule, it is used to impart strength to a rubble foundation that has many voids. Mortar is poured into them, and small cracks are covered. This method is considered quite affordable, but it is used only for foundations with preserved load-bearing capacity.

The cementing composition is introduced using special injectors

Strengthening the base with ebb tides

Sometimes the foundation is reinforced with tides. This technology is used to strengthen platforms made of brick or rubble stone. Reinforced concrete castings are used instead of reinforcement cage.

The work order is as follows:

Reinforced concrete ebbs are installed on both sides and pressed out, while the lower part should touch the wall, but the upper part should not.
The structure is fixed using jacks and screeds.
Then trenches are dug with a 2-meter grip.
The ditches between the wall and the resulting structure are filled with mortar.

Reinforced concrete castings are used instead of reinforcement cage

This technology involves increasing the strength of the platform with double-sided reinforced concrete clips or tubes through which the solution is injected. It fills all the voids in the masonry, due to this the base is strengthened throughout its entire thickness.

At the initial stage, you need to dig out part of the foundation to be repaired. Its length should be approximately 3 m, width - 1 m, depth - 0.5 m.
Then drill through holes on both sides in a checkerboard sequence and insert 20 mm reinforcement rods into them.
After this, it is necessary to attach a frame with cells measuring 150x150 mm to the reinforcement.
At the final stage, the formwork is installed and the resulting space is filled with concrete.

The method of reinforcement with clips allows you to strengthen the foundation along the entire thickness

Shotcrete reinforcement method

This technique is suitable for strengthening a platform that is not too damaged or when planning to add additional floors. Reinforcement with shotcrete will reduce pressure on the platform.

This method uses a concrete cannon, so it is better to entrust the work to specialists. Strengthening the foundation is carried out in several stages.

Video: strengthening the foundation with gunite

Strengthening the strip foundation is carried out using a special technology and includes the following steps:

Video: strengthening the strip foundation

The most common cause of platform damage is soil heaving due to heavy rainfall, floods and freezing of water. In this case, the building seems to be pushed out of the ground and warps. If the house is located in an area with close groundwater and an unstable climate, during construction it is necessary to consider the drainage system and waterproof the foundation. The decision on the best way to strengthen the foundation is made after examining the land plot and analyzing the damage.

Over time, the foundation structure begins to deteriorate. Failure of the foundation occurs due to the old age of the house, untimely repairs and strengthening. If the walls of the building are strong, home owners try to strengthen the foundation. Using this construction procedure, you can increase the life of the house and save money on a new building.

The main reasons for the destruction of the foundation

Quite often, the foundations of old houses are subject to complete or partial destruction of the foundation. This occurs due to the following violations:

non-compliance with the construction technology of the facility;
incorrect calculation of the load on the base;
incorrect house design;
change in soil level;
lack of soil research;
dilapidated condition of the building.

Sometimes the owners of mansions want to add a second floor; increasing the load on the walls and foundation leads to strong sagging and the formation of deep cracks. Before you begin work on strengthening the foundation, identify the cause of its occurrence.

Ways to strengthen the foundation

For each type of house there is a specific method for strengthening the foundation. All buildings can be divided into:

brick;
wooden;
stone.

For example, defects in a wooden house can be eliminated by moving or lifting it. This method is not suitable for stone or brick houses. Each building has its own type of base and all repairs must be carried out taking into account the design of the house.

Strengthening the pile foundation

Before starting work, it is necessary to find out what is wrong with the load-bearing piles of the house. They can either sag or sink a little and change shape. To clarify the situation, as a rule, a pile is driven in next to the foundation, and then a comparison of correctness is made. This means that at the initial stage of construction the main piles could have been driven to the wrong depth, as a result of which the freezing point of the soil was not reached and there was no stop when driving them. If the piles have changed their shape, they must be driven into the ground until the ground is solid. This action will help resolve the problem. If a collapse occurs, then special linings made of metal or wood are installed under the piles.

For detailed instructions on how to do this, watch the video material.

Reinforced concrete support for strip base

To eliminate the emergency situation and strengthen the strip foundation, reinforced topping is used. Strengthening the foundation of a private house is carried out in the following way:

dig around the foundation of the house;
remove the old concrete, widen all the cracks and drill through the base.
insert reinforcing bars into the resulting holes;
remove as much as possible all protruding parts of the base;
We weld the frame to the reinforcing bars;
We make formwork and fill everything with concrete.

Important! Don't skimp on the frame, because... It is he who performs an important function in strengthening the foundation.

Strengthening the brick foundation

The brick base can also be strengthened. For this purpose, durable bulls are made, which are subsequently extended onto the house. Bulls are a concrete block that is built up onto the corners of the plinth to increase the support area and strengthen the structure. How to install bulls correctly?

At each corner, a hole is dug 0.5 m deep from the previous foundation.

Important! The size of the pit is taken into account based on the load and bearing capacity of the soil.

We fix the formwork into the hole.
We install the volumetric frame.

Expert advice! Under no circumstances connect the new frame to the old foundation, because... the new structure will sag a little, which will lead to rupture of the old concrete.

The entire plane is filled with concrete, after 7-8 days it is necessary to remove the formwork and backfill.

Such work should be done quickly and smoothly, because... a house with ripped corners loses its strength and stability.

Sometimes after installing the bulls, experts see that this is not enough to strengthen it. In this case, a comprehensive strengthening of the straight sections of the base is performed. This procedure has several distinctive nuances from installing bulls:

It is forbidden to dig up large sections of the wall; this can lead to the formation of large cracks and the collapse of the foundation. The permissible value is 2 m on one side;
when strengthening the base, it is permissible to connect old concrete with a new structure; it is necessary to tie not only them together, but also individual sections;
installing waterproofing at the joints between blocks, this will protect against the appearance of deep cracks, water ingress, loosening of the foundation and its destruction.

Dry injection method of strengthening

This method is popular among specialists. It can only be accomplished with the help of professionals and the use of special equipment. The work process is as follows:

Wells with an inclination of up to 25 cm in diameter are drilled through the old base. The drilling depth is individual in each case; it is important to reach a solid layer of soil.
The solution is poured into the finished wells and a reinforcement cage is installed.
As a result, the entire old structure rests on an additional number of piles.

Concrete reinforcement

The base can be strengthened using a monolithic frame. This method makes it possible to pour concrete on the side of the building. The entire work process is divided into the following steps:

a trench is dug across the entire area of the building;
the surface of the base is cleaned of soil, dirt and concrete;
drill holes and install anchor rods in them.

Expert advice! If you have the opportunity to carry out work from inside the building, use special through studs.

permanent formwork is assembled in the trench;
a volumetric frame is fixed into it;
then it is tightened with studs and construction anchors;
the entire plane is filled with a solution that is vibrated to fill all the cracks;
after the concrete has dried, it is necessary to waterproof it and build a durable blind area.

Strengthening the base on one side

Sometimes a house can only sink on one side. In order to strengthen the structure, it is divided into several sections at a distance of 2 m. Next, the following work is performed:

a trench is dug deeper and wider from the old base for the initial element;
holes are drilled in the old foundation for reinforcement, with the help of which the old structure is tightened;
they make fines to increase the adhesion of the entire area of the building;
Next, we take the reinforcement frame and rods, they must fit into the damaged base, we install them and cement them;
The formwork is fixed and everything is filled with concrete.

As soon as the concrete has dried a little, proceed to the manufacture and construction of the same new elements to strengthen the building. When all the work is completed, all elements are connected to each other by releasing reinforcement from them.

Complete replacement of the base

The foundation of a house is replaced when it is no longer possible to strengthen and restore it. The whole process is labor-intensive and long. To do this, you need to dig a trench along the entire foundation strip up to 2 m deep, remove the old structure and pour a new foundation. To prevent this method of strengthening, it is necessary to monitor the structure. If cracks or distortions of windows or doors occur, carry out restoration measures.

As you can see, strengthening the foundation can be done on your own, the main thing is to carry out the work step by step, taking into account the technology and the characteristics of the damage that has occurred.

Strengthening the foundation of a private house may be required in different cases, but most often one of the existing methods is resorted to after long-term use of the building. Any building that has served for decades needs repairs. And it is the foundation that requires special attention, since it not only bears the main load from the entire structure, but is also negatively affected by external natural factors, such as moisture, aggressive chemicals in the soil, temperature changes, wind, soil heaving, and more. All this together leads to wear and tear of the materials from which the foundation of the house is built.

In this regard, if repair work is not carried out on time to strengthen and strengthen the strength of the foundation, then there is a risk of its deformation. And as a natural consequence - the beginning destruction of load-bearing walls of the entire house structure. In some cases, the strengthening process can be done on your own. But very often, in order to bring the foundation into proper condition, it is necessary to use heavy special equipment.

Possible reasons for the destruction of the building foundation

If during the control inspection of the foundation, which should be carried out annually by good owners - in the spring, after the snow melts, deep cracks are found on the base, then you should seriously think about urgent repairs.

Perhaps everything is not so bad - only the outer finishing layer has cracked and began to crumble. In this case, the issue is resolved quite simply. But in order to find out whether the foundation walls are affected, the cracks that have appeared will have to be widened.

So, first you need to decide in what cases cracks form in the foundation and its destruction may begin. In addition to “senile wear and tear”, that is, a clearly long period of operation of the structure, such factors include:

Incorrect calculations and errors when drawing up the project
Failure to comply with technological requirements when carrying out “zero cycle” work.
When drawing up the project, no soil studies were carried out, and groundwater levels were inaccurately or incorrectly determined.
The level of seismological activity in this region was not taken into account.
The value of the soil freezing depth was incorrectly determined or completely ignored.

It should be noted that if the technology is violated and the calculations are incorrect, subsidence of the foundation can occur not only in an old building, but also in a newly built house.

In any case, if such a nuisance occurs, you should not give up, since almost always the foundation can be “reanimated” by using one method or another.

If you decide to carry out the process of restoration repair of the base, you must adhere to certain rules. Moreover, it does not matter which technology will be chosen for this:

The perimeter of the building is conventionally divided into sections 2–3 meters long, since the structure is strengthened gradually. First, all necessary measures are carried out on one of the sites, then on the next - and so on until the entire foundation of the building is strengthened.
You cannot begin strengthening the foundation section on the opposite side of the building if the concrete on the strengthened side has not yet gained the necessary strength. The process of solidification of the solution must take at least seven days, and in the cold season (but at positive temperatures) - ten days.

Cement prices

What is foundation strengthening and how to carry out this process

Strengthening building structures refers to activities and actions that change the mechanical properties of the strengthened element of the building. Or they change the structural structure of a unit that is in a weakened state, removing part of the load from it.

There are many methods to restore or even increase the bearing capacity of the foundation. Frequently used technologies are shown schematically in the following table (illustrations can be enlarged by clicking on them):

Illustration	Ways to strengthen the foundation of a house
	Strengthening monolithic strip foundations by installing longitudinal reinforced concrete beams with racks, steel longitudinal and transverse beams and transverse ties on the bottom - in the area of the transition from the plinth to the wall.
	Increasing the supporting platform with the installation of longitudinal beams at the level of the base of the foundation and increasing the thickness of the reinforced concrete strip on both sides, as a rule, using shotcrete technology.
	Increasing the foundation support area using prefabricated elements mounted using steel tie rods and installing transverse steel reinforcement beams at the transition from the plinth to the wall.
	Arrangement of longitudinal beams on the base of the foundation, tied together with transverse anchoring, in combination with additional reinforcement and a reinforced concrete “jacket” applied using shotcrete technology to the tape walls on both sides.
	The method is in many ways similar to the previous one, with the arrangement of a reinforced concrete “cage” on the walls of the belt, but without strengthening the slab part. This option can also be produced using the shotcrete method, with preliminary additional reinforcement of the walls with concrete tape.
	Increasing the supporting part of the foundation with supporting reinforced concrete elements with compression of the soil at the base. Reinforced concrete blocks are connected to each other with transverse anchors. Soil compaction is achieved by wedging the blocks and concreting the resulting gaps.
	Increasing the width of the base of the strip foundation with the arrangement of concrete tides. The tides are connected to each other by steel transverse beams.
	Increasing the area of a free-standing foundation support using tides with associated reinforcement cages.
	Injection cementation of a rubble foundation and the area of contact between the foundation and the soil
	Strengthening foundations with drilled injection piles, which can be done in different ways, depending on which area of the foundation needs to be strengthened.
	Strengthening the bearing capacity of the foundation by installing “oblique” bored piles on the street side and on the basement side of the house.

Restoring an element and extending its service life involves bringing its appearance to its original state by plastering or shotcrete. In some cases, it is possible to improve the mechanical qualities of a structure using injections or application

Strengthening the foundation using gunite technology

The first step is to figure out what this not-familiar word means. Shotcrete is the spraying of construction concrete solutions under high pressure onto the surface of the foundation. Typically this application is carried out in several layers. During the shotcrete process, concrete fills all the voids and cracks of various sizes formed on the wall. To achieve a specific goal, a specific solution composition with various additives is selected. As a rule, a mixture with increased frost resistance and water resistance is selected for foundation walls.

However, this method of foundation repair is suitable in cases where cracks, cavities, and cavities have formed in it. If the base has sagged unevenly, that is, has shrunk, then simply shotcrete will not give anything, and it must be abandoned immediately.

Well, if it is necessary to strengthen the surface of the foundation walls along their entire height, filling the cracks that have formed and increasing the thickness of the tape, then shotcrete is perfect for this purpose.

Methods of carrying out shotcrete work

Spraying concrete under pressure can be carried out in two ways - “dry” and “wet”. The choice of one of them depends on the tasks, the conditions for preparing the solution, as well as the operational capabilities of the installation with which they will be used. work is being carried out.

Dry shotcrete consists in the process of spraying cement-sand mixtures enriched with various additives. The mixture is fed through a hose with a nozzle under pressure in dry form, and is moistened with water only immediately before it comes out. Water is also supplied to the installation at a certain pressure. When using this spraying method, the mixture obtains the required thickness and adhesion.

However, this method has its advantages and disadvantages.

TO positive qualities methods include the following:

— Ease of use of the installation and its cleaning after completion of work.

— Possibility of supplying the mixture at different distances.

— The thickness of the applied layer per pass is up to 60 mm.

— Does not require surface preparation with primers;

— High interlayer adhesion of compounds;

— High efficiency of the device, small amount of waste.

Disadvantages The “dry” shotcrete method is considered to be:

— The need to strictly observe the proportionality of components when preparing mixtures.

— Some experience with the installation is required.

— Difficulties when performing work - dry components can bounce off the surface, getting into the face, which means it is necessary to have protective devices;

— Pollution and dustiness of the work site.

Using "wet" spraying method , the finished solution is supplied to the nozzle of the pipe under pressure created by the concrete pump.

TO "pros" This method includes the following:

— Ease of application due to the high homogeneity of the mixture.

— There is no excess dust in the area where the solution is applied.

— Remaining unused material can be used to perform other work.

— After application, the concrete layer does not require additional processing.

Disadvantages “wet” spraying can be considered:

— Small thickness of the layer applied in one pass, which is no more than 30 mm;

— Longer spraying process;

— More complex cleaning of the installation and supply hoses from the solution upon completion of shotcrete operations.

Work order

The shotcrete process consists of three or four stages - cleaning the surface on which the mixture will be applied, reinforcing the foundation wall, if necessary, making a mortar or dry mixture, and the spraying itself.

The first step is to prepare the surface of the foundation strip wall to be strengthened. To do this, it must be completely freed from the soil, that is, a trench 800÷1000 mm wide is dug along the entire reinforcement area for ease of work. Then the soil is thoroughly cleaned from the surface of the wall, and the old finish is removed if there is a protective plaster layer on the wall. This process can be done manually or using special water-abrasive, sandblasting or hydrodynamic units that clean the surfaces of dirt and old coatings under high pressure. After this, the foundation walls must be thoroughly washed or blown, supplying air or water under high pressure.

A reinforcing structure is mounted on the cleaned wall, which will strengthen and determine the thickness of the sprayed layer. To reinforce the foundation, reinforcing rods with a diameter of 7–8 mm are taken, from which a lattice with cells measuring 80–100 mm is formed. The reinforcement is connected by welding or tying.
The mortar or dry mixture is made from sand and cement in proportions that are basically standard for - this is 3:1 for the atmospheric spray method or 4:1 for mechanical surface treatment. Quite often, a plasticizer is added to the prepared mixture, making the solution more plastic. The prepared solution should be used within two and a half to three hours.

The mixture is sprayed in layers, and the thickness of each layer can be 5÷7 mm. The total thickness of spraying depends on the type of solution chosen, the wall surface, and the method of application. The solution or mixture is applied in a circular motion, holding the nozzle at a right angle to the plane of the wall. Deviation from this angle is allowed if the surface between the wall and the reinforcing mesh is processed, when sealing deep cracks and depressions. Layers begin to be applied from the bottom of the foundation wall in horizontal stripes. The distance between the nozzle and the wall is usually maintained at approximately 1000 mm. The mixture is applied along the entire length of the area to be strengthened. If there is an area nearby where concrete has already been applied, then the joint line with it is processed with an overlap of 200 mm.

If it is not planned to add plasticizers and other additional components to the concrete solution, then each layer is applied only two hours after applying the previous one. If one of the plasticizers is added to the mixture, then the time between applying layers is reduced to 20÷25 minutes.

Upon completion of applying the composition to the entire wall, they begin to moisten it every day with water for seven days - this process will significantly strengthen the gunite coating.

This method of strengthening surfaces is suitable for any type of foundation, except for piles. However, it is inconvenient in that it will not be possible to carry out the strengthening process relying only on one’s own strength, since for this shotcreting it is clearly necessary to have special equipment and master the technique of performing the work.

Strengthening the foundation with reinforced concrete “jacket”

Quite effective The method of strengthening a collapsing old foundation is to build a reinforced concrete “jacket” along the entire height of its walls.

This option of strengthening the foundation of the house can be done independently, if you have a pre-developed project, the necessary material, and experience working with. Due to the fact that quite a lot of concrete solution is required, it will have to be prepared in a concrete mixer. Therefore, if it is not on the farm, you will have to rent such a device. In addition, the tools you will need to have on hand are a hammer drill, a powerful hammer and a grinder, as well as a bayonet and shovel. Maybe, in some cases a crowbar will be needed.

Materials you will need:

— cement grade not lower than PC 400;

— sand, gravel and crushed stone;

— if the foundation rises above ground level, then it is necessary to prepare boards and beams for formwork, as well as waterproofing material (dense polyethylene or inexpensive roofing felt);

— reinforcing rod with a diameter of 12÷16 mm for the frame lattice;

— steel wire for knitting the reinforcing frame;

- roofing felt for subsequent waterproofing of the foundation.

Work on such arrangement of strengthening the foundation is enough labor-intensive, and will be carried out in several stages.

Prices for crushed stone

The first step is to dig a trench around the perimeter of the entire structure, that is, the foundation walls are freed from the soil to its base. If the foundation begins to sag, then after arranging a common trench, it is necessary, starting from the corners of the building, to dig holes 400÷500 mm deep with a certain step, approximately 1500÷2000 mm, directly under the base of the tape. In these pits, support pillars will be placed, which will further strengthen the foundation of the building.

The width of the trench must be at least 400÷500 mm, otherwise it will be inconvenient to dig it. Especially in cases where the base of the foundation is located deep enough in the ground.

Further, if you plan to support the foundation from below, then in the dug pits under it you need to install one of three types of pillars - these can be steel pipes, brickwork or reinforced concrete pillars. For the latter, it will be necessary to make a reinforcement frame, which is installed on compacted pads made of sand and crushed stone, each of them should have a thickness of 50–80 mm. Then, the foundation pit with a welded metal frame is filled with concrete. Now, you need to wait for the concrete to harden and gain strength.
Next, a layer of sand bedding 80÷100 mm thick is made at the bottom of the trench, which must be compacted well. The sand will become a good drainage layer that will remove moisture from under the structure.
After the supports securely hold the foundation at the same level, you can proceed to installing the reinforcement cage under the strip reinforcing structure. This reinforcing belt will be located in a trench dug around the perimeter of the entire house.

In some cases, construction designers, after examining the soil on the site, recommend additional waterproofing of both the old and the reinforcing foundation structure. Roofing felt is most often used as waterproofing, which is fixed to the walls of the main foundation and to the outer wall of the trench.

To connect the old and reinforcing structure, transverse horizontal frame elements can be embedded in the walls of the main foundation. To do this, holes are drilled in them and pieces of reinforcing rods are inserted into the cement mortar. Perpendicular elements of the iron base are welded to the sections protruding from the wall. The remaining parts of the frame are connected to each other using wire twists. Another option for attaching the frame to the main foundation is using anchors.

The width of the frame must be calculated and indicated in the project. It depends on the parameters of the old foundation and the nature of the soil on the site.

If it was necessary to dig a trench larger than the required width of the reinforcing tape, or it needs to be raised above ground level, after forming the reinforcement frame, formwork from boards is mounted on its outer side, which is covered from the inside with waterproofing material. This formwork is reinforced with spacers that are installed at an angle to it. Their other end rests on the ground and is fixed in this position until the concrete hardens in the poured additional tape.
The next step is to pour concrete into the formwork (or directly into an equipped trench with waterproofing-coated walls), with a grade strength of at least M 200. When pouring concrete, it must be periodically pierced with a bayonet shovel, releasing air to the surface, in order to avoid the formation of air pockets inside the monolith first, which subsequently transform into voids that weaken the structure. It is even better if it is possible to vibrate the solution using a special deep vibrator.

After the reinforcing structure has hardened and the concrete has fully matured, the new reinforcing foundation tape must be covered with waterproofing. Typically, roll materials are used for this, applied to surfaces after they have been pre-primed with bituminous compounds.
The final stage of the work involves filling the remaining voids of the ditch-pit with soil. Careful tamping and tamping is required. After this, blind areas are created around the perimeter of the building.

The importance of a high-quality blind area is difficult to exaggerate!

Many people simply forget about this element of the final arrangement of the foundation and plinth of the building, considering it a secondary matter. But such neglect can result in very serious consequences! Read about the significance and how to accomplish it on your own in a special article on our portal.

Strengthening the foundation using drilling injection method

This method of strengthening the foundation of a house is one of the most modern and effective. It consists of installing piles under the base of the house or directly through the wall of the foundation strip, to the required depth, which is determined by soil surveys. A reinforcing structure is installed through the upper hole in the pipe piles. Then, through the same hole, a concrete solution is poured into the pipe, which, after hardening, strengthens the pile. As a result, the foundation receives reliable additional support points, eliminating the possibility of it subsiding into the ground.

When choosing to strengthen the foundation with piles, you need to know that several methods are used to install them in the ground. However, almost each of them will require the use of specialized equipment.

Pile installation methods

Screw method installation of piles can be called the most commonly used when strengthening foundations, and also the most effective. In this case, the piles can be screwed in using special equipment, and sometimes even manually. However, if you choose the second option, you will have to hire assistants for this work. The piles can be placed at an angle, “piercing” through the old foundation strip. If the piles are installed parallel to the walls, that is, vertically, then they are sometimes secured to the old foundation surfaces using anchor bolts or using welding.

Indentation of piles. This method is used in cases where it is necessary to strengthen the old foundation, where vibration and impact processes are unacceptable, that is, piles cannot be driven or screwed in. Therefore, these reinforcing elements are gradually, slowly pressed into the ground. This process can only be carried out using special machines.

Prices for screw piles

screw piles

Bored method. The technology for installing piles using this method involves drilling wells with a certain pitch, which is most often 1500 mm, along the entire perimeter of the building. Wells are installed under the walls of the old foundation and can be deepened into the ground up to two meters. After laying the reinforcement frame, the cavities of the wells are tightly filled with concrete mortar.

So, no matter what method of installing piles in the ground is chosen, they can be deepened at an angle to the structure or vertically. However, most often the option of placing piles at an angle is chosen, since it is not only more effective, but also simplifies the process of installing reinforcement in them and pouring concrete mortar. To strengthen the foundation structure, piles with a diameter of 150÷250 mm are used. And at what angle they will be installed under the base wall is, by and large, not of decisive importance.

Strengthening the foundation with “oblique” piles can be done only from the outside of the tape, or from both sides, that is, both outside and inside. Of course, if the size of the basement allows, since it will be necessary to place a special installation for deepening piles into the ground.

Advantages and disadvantages boroinjection way to strengthen the foundation

This technique of strengthening the foundation of a house is used not only for residential buildings, but also for the restoration of architectural monuments that have stood for several centuries. The advantages of this method include the following advantages and results that are achieved when using it:

Not only the foundation of the house is strengthened and strengthened, but also the walls and ceilings of the building.
Drill injection The method is applicable for restoration work for buildings of any type.
Strengthening can be done on buildings of almost any size. The main thing is that there is enough space to accommodate the required special equipment.
This technology for strengthening the foundation of one building does not cause any damage close located buildings to it.
We can use this strengthening option for houses built on any type of soil.
When installing piles under the foundation or in its walls, the load from the structure is evenly distributed on the ground.
If groundwater passes close enough to the soil surface, then drill injection The method of strengthening the foundation by driving metal piles can be called the only one capable of saving a house from destruction. The pipe, passing through groundwater, will become a reliable protection and formwork for the concrete solution. Without it, the solution will not have the opportunity to set and gain the necessary strength, since its water will simply wash it away.

This method of strengthening has, in fact, one, but very significant drawback - the cost of the work. However, as mentioned above, in some cases such technology becomes indispensable and the only possible option for strengthening the foundation and saving the walls of the building from further deformation and destruction.

Features of the use of pile technology

Buroinjection technology has passed enough serious research tests with high loads. However, don't experiment performing work at random, in order to avoid mistakes and miscalculations. Therefore, it is necessary to note some factors that should be taken into account when carrying out work:

As mentioned above, the slope angle of the installed piles does not in any way affect the reliability of the created structure. Practice shows that a strong increase in the installation angle of piles increases their internal stress, and is completely unnecessary.

Gravel prices

If you plan to mount piles directly through the wall of an old foundation, you need to make sure it is strong enough. If it is not enough, then additional strengthening of the walls will have to be done. For this purpose, a cement-injection method of strengthening load-bearing structures is often used.
For difficult soils complexed with a solution that is poured inside the pile, inert materials such as sand or a sand-gravel mixture can be used.
When strengthening foundations using this method, the technology allows the use of metal profile pipes, round pipes of different diameters, as well as reinforcing rods of different sections. It is important to achieve maximum strength of the structure that reinforces the base.
The length of the piles selected for installation will directly depend on how deep the dense layers of soil lie.
The diameter of the piles depends on the strength of the foundation of the house being strengthened.
The solution with which the pile cavities will be filled must be homogeneous, without large inclusions of crushed stone, as they can contribute to the formation of voids in the concrete monolith and reduce the strength characteristics of the support being created. Therefore, the concrete mixing process must be monitored.

Another way to restore an old foundation

To save a sagging foundation, you can use technology that is developed for the restoration of old architectural buildings that have historical value. Moreover, this method makes it possible to strengthen the foundations of buildings of any number of storeys.

Illustration	Brief description of the operations performed
	The first step along the foundation wall, in the area where the work will be carried out first, is to build a technological pit. Simply put, a trench is being dug for unhindered access to the lower part of the wall of the foundation strip and for placing there technological equipment that will be used during the work process. Next, the wall is thoroughly cleaned of soil.
	Next, using a diamond drilling installation, without strong dynamic influences (which is extremely important if a very old building is being restored), sections of the foundation wall are cut out. These openings should be located with a pre-calculated step - this way you can achieve uniform distribution of the load on the foundation wall.
	If the work is done with your own hands, and there is no high-tech equipment at hand, then the process can be done with the tools that are available, but you must act very carefully. For example, cutting out part of a wall using a grinder. It is not recommended to use a tool with impact or vibration (such as a hammer drill or jackhammer). The drilled or cut pieces of the wall are removed in parts.
	Further, in order to avoid the penetration of moisture into the remaining upper part of the foundation, as well as into the lower masonry of the walls in contact with the reinforced concrete structure during its further arrangement, the ceiling surface of the drilled opening is covered with a waterproofing compound.
	To avoid settlement of the wall masonry, spacer devices are installed in the prepared openings. These elements will become additional reinforcement for the foundation of the house, so they are made from a durable metal profile. For example, they can be used as pipe sections of the required height, which are installed by surprise.
	The next step is to stop at the openings of the reinforcement cage. Lattices are knitted from rods to cover the entire thickness of the foundation wall.
	Then the upper reinforced concrete belt is concreted using grips. The joining of reinforcement frames of adjacent grips is carried out using threaded connections of the “Lanton” type.
	Now that the walls of the house have been provided with the necessary support, they proceed to installing piles. To do this, the lower part of the foundation is dismantled, freeing up space for installing pile supports.
	Installation of piles is carried out using indentation technology using composite reinforced concrete elements, from which the piles are made. Special equipment is used for this process. This technology is gentle on the entire structure and its operating mode. If it is not possible to use this option for installing piles, you can use another technology, in which a pit is opened in the freed space in the ground, in which a monolithic reinforced concrete support is installed. This design can also involve piles in conjunction with the main foundation, that is, they are installed in a monolith. From the classical method of pressing piles, we can take the fact that the piles are mounted in separate segments.
	In order to avoid weakening of the piles during the operation of the building, each of them is immediately loaded, that is, with the help of spacer elements a certain support tension is created.
	The piles supporting the foundation and walls are installed in the same order using the method of sequentially bringing them closer together. That is, starting from the corner of the building under one of the walls, and the other wall is strengthened in parallel in its central part.
	Then, work is carried out to bring them closer together until the entire foundation has reliable support.
	Soil removed from technological pits is not returned to its place. In the area freed from it, a layer-by-layer protective structure is formed - reservoir drainage, consisting of the following materials: underlying geotextile, drainage layer of crushed stone, another layer of geotextile, concrete preparatory layer, primer impregnation and installation of roll waterproofing, power floor and lower reinforced concrete monolithic belt. Thus, the upper part of the piles, deepened into the ground, will be covered by a concrete belt, which will make the support more durable.
	The result of strengthening the foundation using this technology will be the stabilization of the building's settlement and the creation of a single pile foundation on a concrete slab grillage. Of course, at first glance the technology seems complicated, but upon closer examination and a more careful approach, one can be convinced that when using it it is quite possible to do without complex equipment. However, you need to prepare for the fact that you will have to put in quite a lot of effort, so it is best to enlist reliable assistants with experience in the construction of engineered concrete structures.

A few final words. The use of any of the technologies described above must be justified by special research, measurements and calculations. It is almost impossible to produce them yourself with the required degree of accuracy, and acting at random can aggravate the situation to the point where weak sections of the walls may collapse. Therefore, restoration with strengthening and strengthening of the foundation is best entrusted to qualified specialists who are able to objectively assess the situation and make a decision on one way or another of the work.

And to supplement the information received, watch a video in which an experienced master shows the process of strengthening a strip foundation.

Video: Option for carrying out work to strengthen a subsiding foundation

The foundation is the basis of any building. The longevity of the building depends on its reliability and quality. An erroneous choice of the type of foundation and miscalculations when laying it will eventually cause defects, which sooner or later will lead to the destruction of the entire structure. Therefore, at the first signs of deformation, you should immediately determine the causes of its occurrence and begin to eliminate them in order to avoid an expensive complete replacement of the foundation.

Signs and causes of partial destruction of the foundation

Strengthening the foundation should be carried out in two cases: when signs of structural deformation are detected and when it is planned to add floors. Before starting work, you need to carefully analyze the condition of the house, assess the degree of destruction of the foundation or the likelihood of defects appearing in the near future, and only then begin strengthening work.

Most often, professionals with special equipment are invited to identify flaws. But you can do the work yourself if you correctly evaluate all the factors and follow the step-by-step instructions for strengthening the foundation. There is only one thing you cannot do when defects are discovered - ignore them, so that later the inevitable replacement of the foundation does not cost a lot of money.

The initial stages of destruction can be identified by several obvious or hidden signs. Obvious signs are visible to the naked eye, these include:

the appearance of deformations on the floor surface;
changes in soil level and the formation of gaps around the base;
defects in the exterior decoration of the house or its destruction;
small cracks on the walls and base;
local minor destruction in the building itself and in the adjacent area.

Barely noticeable cracks have already appeared on the base of this house. If urgent measures are not taken, then all this beauty, unfortunately, will be destroyed

Hidden defects are more difficult; special equipment is required. However, if at least something worries you, for example, part of the decorative plaster on the facade or base has peeled off, or the soil around the house has slightly subsided, do not waste time and money on specialists.

This way you will save yourself from more serious problems. Specialists will quickly find out the cause and tell you how to eliminate it. And if you wish, you can do the work yourself.

The destruction of the foundation of a house occurs for many reasons. The main ones:

In addition, the influence of the environment has an impact: small underground fluctuations, sudden warming, temperature changes, prolonged rains and an abundance of snow, as a result of which the groundwater level rises and the processes of soil heaving begin.

Under the influence of frost heaving, cracks appear on the walls of the house. This indicates the beginning of foundation deformation

Of course, it is impossible to foresee all the harmful consequences of natural disasters, but risks need to be calculated at the stage of designing a house.

Preparatory work before strengthening the foundation

Preparation for strengthening the foundation is divided into 2 stages - examination of the foundation and its unloading.

Foundation Survey

Inspection of the foundation of a building can be planned (periodic inspection so as not to miss the beginning of destruction) and unscheduled. The latter is carried out:

The study is carried out differently depending on the approach to the constituent elements of the structure and the magnitude of the destruction. The easiest way is to carry out a visual inspection and record the detected flaws in a photo or video in order to observe the defects.

External inspection is done in easily accessible, clearly visible places without any tools. They mainly inspect the pits, the upper surface of the base, its base and grillage. Pay attention to corrosion of concrete, reinforcement exposed due to chips, destruction of masonry, the appearance of gaps, rust and cracks, and violation of the integrity of the monolith.

A visual inspection is usually carried out during the day, but it does not give such clear results as an instrumental examination using special equipment.

Instrumental control is necessary in the following cases:

when the deformation area of all sections exceeds 10% in total;
if the spatial arrangement of the structure is violated (this may be a tilt, shift or settlement);
if the chip depth reaches 1.5 cm.

Before strengthening a reinforced concrete foundation, it is first determined whether its shrinkage has stopped - beacons are installed across the cracks and observed for a month. If no changes are found, strengthening work begins.

Unloading the foundation

This is the final, but very important stage of the preparatory work, since it allows you to prevent distortions when strengthening the foundation. Yes, and interfering with the structural basis of any structure without redistributing the load completely or partially onto temporary structural supports is fraught with destruction of it as a whole.

Partial unloading (redistribution) is carried out using temporary wooden supports, as well as metal or wooden struts. In the underground room or on the lower floor of the house, at a distance of about 2 m from the wall partitions, support pillows are laid, and on top of them - a beam with racks. The upper purlin is attached to the posts with anchors (as shown in the figure). After this, wedges are driven in between the supporting lower beam and the uprights, transferring the load from the floors to temporary supports.

Scheme of partial unloading of the foundation using temporary wooden supports: 1 - foundation, 2 - walls, 3 - floors, 4 - upper girder, 5 - rack, 6 - wedges, 7 - support beam, 8 - support pad

Complete unloading of the base is done using foundation beams (they are called rund beams) or transverse and longitudinal beams made of reinforced concrete or metal:

Ways to strengthen foundations

After an examination of the ground structures of the building and the foundation itself has been carried out, the causes of destruction have been established and the foundation has been partially or completely unloaded, strengthening work can begin.

This is a lightweight and convenient technology that is suitable for strengthening shallow foundations. You can do it yourself.

Strengthening the foundation with a reinforced concrete cage is a simple and affordable technology with which you can easily repair a deformed foundation yourself

For the work you need concrete grade 400, reinforcement Ø 16–18 mm, wire, anchors and injection tubes (if their use is intended).

The result is a reinforced concrete belt (clip), which rigidly fixes the foundation and prevents its further deformation. If the bearing capacity of the original base is insufficient, the cage is made with a widening at the bottom.

For rubble foundations with a large number of voids, injection tubes are used, installed in the foundation so that they extend 35–40 cm beyond the walls of the casing. Through them, cement mortar is pumped into the foundation cavity after the casing has completely hardened. The solution fills the voids and adheres to the surface of the foundation, and the clip forms an additional contour that ensures the integrity and strength of the foundation. After two to three days, the injection tubes are cut.

Strengthening foundations with a large number of voids is done using a concrete clip and injection pipes

Strengthening the foundation with a reinforced concrete jacket

Strengthening the base with a shirt is done in the same way. The only difference is in the size of the coverage - the clip covers the entire perimeter of the foundation, and reinforcement with a jacket is done only on damaged surfaces.

The technology of reinforced concrete jacket reinforcement has proven itself well for the reconstruction and repair of strip and column foundations

This strengthening method strengthens columnar and strip foundations well.

Strengthening the foundation with ebb tides

This technique is used to strengthen brick and rubble foundations. Its principle is as follows: instead of a reinforcement frame, reinforced concrete castings are used:

Strengthening the foundation by widening the sole

The sole is a supporting reinforced concrete structure for the base. It can be widened by laying slabs or installing a reinforced concrete pad. The technology for widening the sole in both cases is quite complex, but with the help of several people you can cope with this task without involving professionals.

Shotcrete reinforcement is an ideal option for repairing the foundation of a brick house. It is very difficult to do such work on your own; it is better to entrust it to specialists.

Scheme of strengthening the foundation with shotcrete: 1 - reinforced foundation, 2 - reinforced brick wall, 3 - reinforced concrete frame, 4 - anchors, 5 - above-basement floor, 6 - basement floor mark, 7 - area of compressed foundation soil

If you are confident in your abilities, then you will need:

perforator;
shotcrete gun;
gravel, sand and cement;
shovel.

Strengthening the foundation takes place in 2 stages: first, work is done on one side of the foundation and only after a week they move to the opposite side. This time interval allows for maximum strengthening of the structure. Capture areas must be at least 2.5 m in length.

Reinforcement with shotcrete is considered one of the best strengthening schemes, since it significantly increases not only the bearing capacity of the foundation, but also its water resistance.

Strengthening the foundation of a house with cementation

Cementation (injection) - filling base cavities, voids and cracks along the entire length. It is done both to strengthen the foundation of the house and to prevent excess moisture from seeping deep into the structure.

Reinforcement is carried out manually or using a special injection pump.

An interval of two to three days should be maintained between constructing the cage and filling the pre-inserted tubes. It makes sense to carry out cementation if the foundation of the building has not lost its load-bearing capacity.

It is also possible to restore the bearing capacity of the foundation by filling cracks, voids and seams using modern mixtures and resins, for example, MC-Injekt 2700 (injection resin) and a pump.

Strengthening the foundation with piles

Today, in areas with heterogeneous soil, the method of strengthening the foundation with screw piles is popular. It is good because the piles used, thanks to the unique design of the blades, can withstand loads of up to 25 tons. However, this method of reinforcement is very expensive and requires special equipment and the participation of professional builders.

Conduct a soil study to determine its moisture level and density. Based on the results of the study and data on the condition of the foundation, the number of piles, their installation locations and the required amount of concrete are calculated.
They strengthen the corners of the house by making tunnels to access the foundation, then the foundation is washed and dried for 24 hours. Reinforcing rods are placed in the foundation walls so that they extend into the trench, where a load-bearing frame is formed on their basis.
First, they strengthen the corners of the house - they dig under the foundation and clear it of soil.
In each corner, two (or more) piles are screwed in on both sides and reinforcing bars are welded to them. It turns out to be a monolithic block around the base from a reinforcing belt and piles.
The reinforcing belt is welded to the piles, which are installed in the corners of the building
Concrete is poured into the trench. This is done in 2 steps: first, concrete is laid to half the height of the base of the structure, and compacted with a vibrator. After the first layer has hardened, formwork is made and the remaining solution is poured.

Video: strengthening the foundation - tightening screw piles

Micropiles Ø 150–300 mm

A good way to strengthen it is convenient, uncomplicated and affordable. Allows you to combine drilling with injection. The hoses used in this case remain inside the pile, which ensures reliability and high quality reinforcement.

Indentation piles

They are used to strengthen the foundation of buildings on hard soils. To perform the work you will need special equipment. To ensure better connection between the foundation and the piles, beams are installed in the base.

External piles

This strengthening method is used in areas with high groundwater levels. The base is placed on piles, having first passed a reinforced concrete beam through it, which will hold the structure.

To strengthen the foundation, an iron beam is passed through it and then outrigger piles are placed under it

Bored piles

Deep holes are drilled at an angle to the old foundation, reinforced and filled with concrete.

Strengthening areas are selected and internal and external wells with a diameter of 170–240 mm are drilled at an angle of 45° to a depth of solid soil.
A pre-made reinforcement frame is lowered into them and the concrete mixture is poured under high pressure. After hardening, the entire structure is secured to the base with anchors.

Strengthening the foundation with bored piles is easy to do with your own hands if you have the appropriate equipment

Advantages of this technique:

all load-bearing elements are strengthened: foundation, interfloor and attic floors, blind area, walls, basement;
no need for a large amount of excavation work;
suitable for any type of building;
good results in a relatively short time;
along with the reinforcement, waterproofing of the base is additionally provided;
This scheme is effective on the most difficult soils.

The main disadvantage of the described scheme is the need to use special equipment. Therefore, despite the fact that the process itself is not very complicated, this technique is used quite rarely.

Strip foundation strengthening technology

Strengthening the strip foundation is carried out in sections, preventing the entire foundation from being excavated at once. You can speed up the work if you carry it out from different sides at the same time.

If you do the repairs yourself, you can do without piles. After cleaning the old foundation, a reinforcing structure is created in the trench. They make formwork and fill it with concrete.

Video: strengthening the strip foundation

New high-tech ways to strengthen the foundation

One of the new methods of strengthening is the DEEP INJECTION technique, which helps restore and strengthen the bearing capacity of the foundation. It requires a large amount of excavation work and the use of heavy construction equipment.

Using DEEP INJECTION deep injection technology, the geopolymer composition is injected directly under the base of the foundation

The method is based on the point introduction of a two-component polymer resin into the thickness of the earth. Thanks to the action of the polymer, the voids are filled, moisture is forced out of the pores, the foundation of the house is compacted and raised to its previous level. At the same time, the load-bearing capacity of all structural elements increases.

If the house is built on a weak site and has already begun to sag, then it’s time to try another know-how - POWERPILE technology, which strengthens the soil and restores the load-bearing properties of the foundation.

Injection pipes in a Kevlar shell are driven into the ground to a depth of 6 m and filled under pressure with a geopolymer composition that expands and hardens. A kind of polymer pile is formed. It resists shear and fracture loads equally well, therefore significantly increasing the strength of the base.

The SLAB LIFTING technology also deserves attention, which will stop the subsidence of the concrete floor slab, raise the structure to the level specified in the project, and increase the load-bearing power of the foundation.

Video: DIY foundation repair

It is, of course, impossible to describe all technologies for strengthening foundations. Each methodology is developed individually, taking into account the results of surveys and design indicators. Owners of private housing construction need to remember that do-it-yourself strengthening work can only be carried out after a thorough inspection, receipt of examination results and relevant conclusions.

Strengthening a strip foundation is a complex process that is performed using various methods. The immediate need to strengthen the foundation is indicated by the appearance of cracks and deformations of various kinds. There are many reasons for the destruction. The main ones are often associated with a violation of construction technology or an increase in the load on the supporting structure due to the completion of the structure. The choice of reinforcement method in each specific case depends on the nature of the damage, the properties of the soil, and the condition of the structure being repaired. At the same time, proper restoration work will significantly extend the life of the building.

Causes of foundation deformations

The appearance of cracks in the base or its deformation is a common occurrence. It occurs during long-term operation of a structure without regular preventive repair work or due to the action of factors beyond human control. From the foundation, faults and wall shifts are transmitted to the structure. If this process is not stopped in a timely manner, the building will collapse.

The destruction of the foundation strip occurs for the following main reasons:

vibrations (movements) of the soil caused by an earthquake or blasting operations near the building;
an increase in the weight of the structure during its reconstruction (due to the use of heavier materials) or the addition of floors;
use of low-quality materials for the construction of a supporting structure for a building;
the location of the building on a sloping site, which can result in a landslide or slow sliding of the soil;
digging pits and trenches at a close distance from the structure;
deviation from construction standards and technology of work during the construction of a building;
changes in the load-bearing properties of the soil under the building caused by rising groundwater, severe freezing and other factors;
failure to comply with operating rules, failure to carry out timely repairs;
flooding of the area around the building and the absence of a drainage system;
incorrect calculation of the bearing capacity of the foundation;
significant shrinkage of the structure.

For some reasons, in addition to restoring the foundation strip, it will be necessary to carry out additional work aimed directly at eliminating them. An example of such measures is the creation of a drainage system, strengthening of nearby soil (even a slope), waterproofing the base. Without such work, the destruction of the foundation will continue even after repairs.

Regardless of the reason that caused the destruction, repairs should begin as quickly as possible. Postponing it can lead to more serious problems, as well as a significant increase in costs associated with this: when the cracks move from the foundation to the walls of the house, then we will be talking about saving the entire building.

Inspection of the base before repair work

Repair of a shallow strip foundation (or another type) begins with an underground and external inspection. The first is aimed at accurately determining the dimensions of the foundation and the material used for its construction, as well as assessing the strength of the supporting structure. Using an external inspection, existing cracks and chips are found.

The nature of the destruction and the location of its occurrence on the supporting structure under the building make it possible to determine the cause of the process. Before carrying out work to strengthen the foundation, you should install beacons on the cracks (it is enough to do this in two places). If after a month they have not burst or fallen off, this indicates that the shrinkage of the structure has completed. You can begin the main work, in some cases simply by sealing the cracks.

When the beacons fly off or break, then it is necessary to strengthen the base. Those who have not previously had to carry out such work on their own are recommended to seek help from professional builders so that they do everything efficiently.

A preliminary inspection allows you to determine the scope of the upcoming repairs, as well as establish the cause of the damage and select the additional work necessary to eliminate it. Thanks to this, you can calculate upcoming expenses.

Technologies for strengthening strip foundations

Strip-type foundations are built mainly from brick, stone, concrete, ready-made reinforced concrete blocks and rubble concrete. The option is chosen depending on the upcoming load and the characteristics of the soil on the site. Depending on the depth of occurrence, there are the following types of strip foundations:

shallow;
recessed

Foundation tapes are also divided by shape (in cross section) into trapezoidal and rectangular supporting structures.

Regardless of the types of strip bases, they are strengthened in the same ways, choosing the most suitable option for a particular case.

When the soil under a building changes its structure due to the action of various factors (with a decrease in bearing capacity), then the method of strengthening is its replacement.

In practice, the following methods of repairing strip foundations have also become widespread:

reinforcement with piles of various types;
partial restoration of destroyed areas;
construction of a reinforced concrete belt (jacket).

The latter method allows you to fasten the entire supporting structure. This prevents existing cracks from growing and new ones from appearing.

If it is necessary to remove excess water from the site, it will be necessary to create a reliable drainage system.

The volume of upcoming restoration work is determined by the degree of existing destruction. The methods used to strengthen the base will depend on this. In some cases, it is enough to simply cover up small cracks and replace a section of the thermal insulation coating along with the waterproofing. More complex situations may require both expansion of the foundation and partial or complete replacement. Those who have not done this before will need the help of specialists.

Installation of piles

To strengthen the MZLF and buried foundation, the types of piles presented in the table below are used. It also describes the features of their use.

№	Types of piles used	Features of application
1	micropiles	convenient to use because their installation can be combined with the introduction of the solution
2	bored	their installation involves pouring concrete into holes drilled in advance through 1.5 m with a depth of about 2 m (with a reinforcement cage inside), located inside and outside the structure
3	metal	are installed on both sides of the tape, while they are connected with a reinforced concrete structure
4	pressable	used when the load-bearing soil layer is located at a significant depth

The diameter of the micropiles used is 15-30 cm. Installation of pressed-in piles requires special equipment, which increases the cost of repair work.

The piles take on the actual load. In this case, openings are made in the foundation into which beams are mounted. Through them the load is transferred to the pillars. Piles can also be installed at an angle through the body of the foundation of the building being repaired.

Installation of reinforced concrete jacket

This method of strengthening the foundation tape has become widespread among owners of private houses. The technology itself is simple, so you can do without hired builders.

Before carrying out work, you must first stock up on the required amount of material: reinforcing bars (section 16-18 mm) and M400 concrete (or cement, sand and small crushed stone for preparing the solution yourself).

The creation of a reinforced concrete reinforcing belt is carried out in the following sequence:

dig a trench along the foundation along its entire perimeter with a depth level with the existing foundation or greater (approximately 0.5 m);
make notches on the foundation surface;
install the reinforcement frame, connecting it with anchors to the base;
install formwork of the required height;
fill the reinforcement with concrete, compacting it well;
after the solution hardens, the shields are dismantled and the monolith is waterproofed;
the remaining voids are filled with earth.

To compact concrete, you can use a vibrator or a regular pin. If the technology is followed, a foundation structure reinforced with reinforced concrete can last for a long time. It forms a single whole with the old base. For heavy buildings, it is recommended to install pile supports.

Partial foundation repair

If there are no displacements of the tape, and the cracks are small and do not increase in size, then it is possible to limit ourselves to partial repair of the damaged area.

Minor cracks can be repaired as follows:

inspect the base;
cracks are filled with concrete mortar with various additives;
install tightening metal plates or reinforcing mesh along the fault;
plaster the surface to be repaired.

These simple actions often help stop the destructive process. But if the reason remains, then soon repairs will be needed again. The collapsing areas of the tape are reinforced with reinforced concrete. To achieve a better result, it is necessary to properly waterproof and insulate the base.

Shallow foundation: strengthening work

Quite often, individual developers erect light buildings (for example, bathhouses, sheds, even cottages) on shallow foundations. A common method of repairing them is to deepen and widen the tape.

Restoration work is carried out in the following sequence:

completely tear off the collapsing sections of the base about 1.5 m long;
to strengthen the tape, concrete is poured (it must be compacted), a reinforcement cage installed in advance in the resulting recesses, or reinforced concrete blocks are laid;
compact the surrounding soil.

When using blocks, the joints are filled with concrete.

In cases where it is necessary to radically strengthen the tape, it is recommended to use pile supports: screw, bored or drilled. To use the latter, you will need to resort to the help of contractors, because you will need the preliminary creation of drawings and special equipment. Bored injection piles are an expensive reinforcement method that pays off when replacing the entire load-bearing base of a building.

The process of strengthening the foundation of a multi-story building is presented in the video below.

If the foundation strip is deformed or even small cracks appear on it, repairs should begin. Delay can lead to disastrous results and increased costs. It is recommended to first inspect the foundation and determine the cause of the damage. After this, you need to choose the appropriate method for restoring the supporting structure and decide on the necessary accompanying measures.

You can carry out partial repairs, install a reinforced concrete jacket and some types of piles yourself if you have the appropriate skills and experience. On the construction forum you can get answers to your questions on each specific case.