If the foundation fell into disrepair during operation - it began to crumble and cracks appeared on it, then the main cause of such defects may be non-compliance with the rules of the technology when pouring. Perhaps the foundation was constructed using low-quality concrete. In some cases, negative factors affect the materials, and waterproofing is carried out poorly. In any case, over time, the foundation may require strengthening.
If the house is built on soft ground, then the foundation loses its ability to withstand the loads that turn out to be a structure over time. In this case, reinforcement of the structure may also be required. These works extend the life of the entire building. Reinforcement can be carried out in several ways, which depend on how much of the base should be reinforced.
Work on the grillage
To date, there are several ways to strengthen the grillage of the pile foundation, which depend on the causes and type of damage. The process of restoring parts of a shallow and buried foundation is no different. Strengthening the pile foundation with grillage provides for the repair of defects in the outer concrete layer. In this case, a cement mortar is used, which is applied to the surface of the damaged area under pressure. This approach eliminates cracks, corrosion, and weathering effects.
The works are called shotcrete. Before they begin, the surface of the grillage must be treated with a metal brush, and then blow out with a compressor and rinse with a stream of water, which is supplied under pressure. For reinforcement, a metal mesh should be used, the cells of which have a size ranging from 5 to 10 mm. The basis should be a wire with a diameter of 5 mm.
Using a puncher, in the next step, holes are drilled on the damaged side. It is necessary to go deep by 25 cm, and the distance between the holes can be from 50 to 80 cm. Anchors are inserted inside, to which a metal mesh is fixed. The application of the gun is carried out under pressure within 0.6 MPa, while the layer thickness can reach 40 mm.
Work is carried out in such a way that as a result centimeter strips are obtained. It is necessary to act from top to bottom. After the first layer has set, you can begin to apply the second and third. When considering ways to strengthen a pile-screw foundation, you should pay attention to another technology that helps eliminate larger damage to the grillage. To do this, drill holes in the damaged area, placing them at an angle to the piles. These holes are called holes, and they must be positioned in such a way as to cover the damaged area as much as possible.
The diameter of the holes can be from 40 to 80 cm. The holes will have a length within 0.4 of the thickness of the foundation. This is true if drilling is done from two sides. Whereas when making holes on one side, the length of the holes should be 0.75 of the thickness of the base.
The number of holes is not limited and will depend on the size of the repaired area. It is important to place the holes between the bars of the reinforcement. After the completion of the arrangement of the holes, they should be washed with a stream of water and filled with concrete mortar, which is prepared in a ratio of 1 to 10. If the grillages are more impressive, then a clip is constructed on the damaged area. Strengthening with its help is carried out at the entire height of the grillage and along its entire length.
Strengthening trunks
Quite often, reinforcement is used to reconstruct the base. How to strengthen the pile foundation, you can find out if you read the article further. The most convenient way is to strengthen the base with a high grillage, because the trunks are available for repair. If there are cracks on the pile pillars, a reinforced concrete cage with a thickness of 10 cm is to be installed. Digging into the ground is 1 m or more.
Strengthening piles can be accomplished by drilling the hole with holes of small diameter. On each side of the support, 8 cm holes are drilled for this. One must be on each side of the support. A cement mortar is poured into the wells, which forms a concrete jacket around the support and enhances the strength of the soil.
Strengthening the pile foundation can be carried out in the field of columns. For this, a reinforced concrete or metal pile is hammered to the support shaft. Conical metal pipes are pressed in when repairing columns in existing workshops and during repair work in the basement.
Steel pipes are used for the sheath of piles, the length of which can vary from 2 to 3 m. In weak soil, the elements are squeezed out by a jack until the moment when it is not possible to reach a solid base. In the process of deepening one pipe, a second one should be welded on it until it reaches the design mark. After the pipe is submerged, it is poured with concrete.
Additional ways to strengthen the supports
The pile foundation can be strengthened by placing additional supports next to the grillage. Such piles should be located on both sides of the base, and a beam is installed on their heads. To strengthen the structure in this way, the beam must be installed under the foundation itself or the frame of the building.
To prevent piles from sagging, the head is crimped with jacks on both sides. If a gap is formed between the column head and the beam, then metal wedges are placed there. This place at the next stage needs to be reinforced with reinforcement and filled with concrete.
Pile reinforcement with bored piles
Strengthening the pile foundation can be carried out using bored supports. Two columns are made near the columns, and then reinforcement and filling the space with concrete are carried out. In this way, it is not worth reinforcing all the posts in a row, the work should be carried out through one or two supports.
There are cases when the strengthening of the entire base is carried out. Such work is relevant for significant destruction. The main reason for such consequences may be an increase in the bearing load on the base and weakening of the soil.
Foundation reinforcement by soil compaction
When the soil under the supports loses its bearing capacity, it must be strengthened. There are several methods for this, the simplest is the replacement of sagging soil. Strengthening can also be carried out by the method of digging up the supports to the lower conical part. In this case, the soil can be compacted by pouring cement mixture or silicate resin.
The reinforcement of the pile foundation installed on clay soil is carried out by the method of injection into the soil around the supports of urea resin. Soil strengthening is carried out through submerged injectors, with the help of which the resin is pumped from both sides in turn by steps from bottom to top.
Pile screw foundation reinforcement
Strengthening the pile-screw foundation may include the use of pipes or a steel corner. The size of the first product should be 30 x 60 mm, as for the corner, then its shelf should be equal to 50 mm. These elements are installed around the perimeter, internal supports should not be excluded. In the end, you should get a structure in which all the piles are connected. This type of reinforcement of the pile-screw foundation is used when the supports are located high above the ground surface (more than 70 cm).
Work methodology
Welding with a corner or profiled pipe enhances spatial rigidity. The elements should be placed voskos between the two supports at a low lifting height on the inside of the base, so as not to interfere with the installation of panels decorating piles. If the upper part of the supports protrudes more, then welding is carried out crosswise, and in the central part of the intersection of the elements, a steel plate is installed with dimensions equal to 200 x 200 mm.
Alternative pile reinforcement
Strengthening the pile foundation during the reconstruction of the building may also include the use of a channel, the dimensions of which are 160 or 200 mm. This method is used when the building is erected on peat soil. The width of the channel will depend on the thickness of the walls of the house. This element is welded to the top of the supports and replaces the head. Welding all piles creates a rigid and durable structure that is similar in principle to a strip foundation.
Using channel
If the pile foundation is reinforced during the reconstruction of the building using a channel, this increases the cost of the structure by 50% or more. The final cost of the foundation will be lower than the price of the strip foundation, while the speed of construction of the first foundation is not equal. For example, if you plan to build a house 6 x 6 m, then it will require 12 supports, their average cost will be 43,200 rubles. An additional 25,500 rubles must be added to the channel, the total amount is 68,700 rubles, while the delivery of the material is not taken into account.
Strengthening the pile foundation of an existing private house can be carried out by jacking the building to a minimum height. The use of the channel allows you to solve another problem, which is expressed in the sagging of the strapping ring. This eliminates the trampoline effect when the distance between the supports is too large.
Additional reinforcement using soil reinforcement
The soil around the trunks under their base can be strengthened in the following ways:
- resinization;
- cementation;
- silicatization;
- firing.
A specific technology is selected taking into account the type of soil. The method of reinforcing the pile foundation, expressed in silicatization, is relevant for forest and sandy soils, while resinization can be used for fine sands. For clay soil and gravel soil, cementation is best suited. These methods are implemented according to one technology, however, the methods differ in the composition of the solution injected into the soil.
Conclusion
During operation, the foundation may be aggressive. This should include groundwater and precipitation. In order to eliminate corrosion, piles are recommended to be protected with special paints, but sometimes this is not enough. Over time, it is necessary to strengthen the foundation, which is suitable both for new construction and for overhaul of old buildings.
Such work may also be necessary when shrinking the foundation, the cause of which is still the same groundwater, temperature changes and errors in the construction of the primary foundation. In order to preserve the building, it is necessary to strengthen the foundation. The technology for implementing this idea has long been worked out. The house must be raised and the corresponding work carried out. However, the likelihood of such work must be foreseen at the design stage of the building, then the costs will not be so impressive.