Five ways to make screw piles last forever

Many have doubts about screw piles. The questions are not only about the difficulties with insulating the perimeter of the pile field, they impose restrictions on the types of wall materials that can be used for this foundation. Although, there are situations where you cannot apply any foundation other than screw piles (swamp or slope). The main doubts about screw piles are their durability. Metal in the ground, and who studied in practice how long they will last? Indeed, in addition to the usual oxidation corrosion, steel can also undergo electrical corrosion, which destroys the metal even faster.

The situation is especially deplorable when the screw part of the pile separates from the pipe and the pile loses its bearing capacity and starts to fail. How long can this take? 20 years old, 30 years old? Or will this never happen?

The diameter of the pipe (pile shaft) is used: 57, 76, 89, 108, 133 mm. And with different blade diameters for the design load and bearing capacity of soils. How can they be protected against corrosion?

Here is the first option to make screw piles almost eternal, for the entire life of the house:

1. Reinforcement and concrete pouring of the pile shaft

In this case, it is necessary to choose piles with an increased diameter - 133 mm. A frame of three reinforcement rods is inserted inside and poured with concrete with vibration (tapping). The head (support platform) is welded to both the pipe (trunk) and to the reinforcement coming out through the platform. By the time the steel collapses, the concrete will still carry the loads from the building.

Also, this method is applicable in those cases who make a concrete grillage supported by screw piles. But the grillage itself should not rest on the ground. I saw examples when block walls were placed on such a structure. And it was used because of soils with poor bearing capacity (peat layers several meters thick).

The second method was shared by the developer of the facade system from blocks in one of the articles:

2. Galvanic protection

Screw piles installed competently live easily up to 50 years. For those who are going to live longer, there is a very good and inexpensive way. We used it to protect metal structures in seawater. It consists in connecting a zinc electrode to the pile field. It must be buried in the ground in the wettest place and changed every 7-10 years. And the piles will live forever.

You can also use a magnesium electrode. This is the so-called protective pipeline protection.

Galvanic electrochemical protection is used on oil and gas pipelines that are laid in the ground:

Cathodic protection of pipelines

The next way to protect the metal:

3. Galvanized screw piles

Manufacturers who use hot-dip galvanizing of all piles (with immersion) still need to look. But instead of simple painting, zinc plating protects against corrosion much more effectively.

Two more options:

4. Coating the trunk with bitumen mastic after the installation of the pile field

During the installation of piles, the paint on them is damaged, scratched by the soil. And paintwork protection loses its effectiveness.

Because corrosion on the pile most of all appears in the place of its exit from the ground (constantly wet place and there is more oxygen at the surface), then it requires enhanced protection. You need to dig out each pile 20-30 cm, treat it with bituminous mastic, let it dry and bury it back.

5. Shrink sleeve for pile shaft

Before the main screwing of the pile into the ground, a large-diameter heat-shrink sleeve is put on the trunk, heated by a burner to create a tight contact with the pipe.

This method of protecting the pile shaft at the point of its exit from the ground is not common, but it is available in the arsenal of technologies from experienced companies that mount screw piles. It is used in water-saturated and swampy soils.

These methods can be used in combination. It all depends on your wishes and the amount you plan to spend on the foundation.

***

Photo taken from open sources, from Yandex. Pictures

Subscribe to the channel, add it to your browser bookmarks (Ctrl + D). There is a lot of interesting information ahead.