Many ways can be used to protect steel screw piles from corrosion so that they remain structurally sound throughout their service life. This article discusses some of the pros and cons of the common methods that can be used to protect those screw piles from corrosion.
A direct current (dc) can be introduced into the steel screw pile in order to save the pile from being consumed by galvanic corrosion originating from the steel's interaction with the soil at the point of installation. The use of an impressed current to protect the piles often makes it unnecessary to use other protection methods, such as galvanisation. However, this protection method can be expensive. For example, you must always pay for the power that is used to create the impressed current in the screw piles. Furthermore, routine maintenance is needed to keep the circuit through which power is flowing stable.
Another way to protect steel screw piles involves enclosing the piles in several inches of concrete before they are driven into the ground. About 3–6 inches of concrete are sufficient to provide the needed protection. This method is affordable and quick. However, one may need more torque to drive the piles into the ground. This is because the added thickness of the concrete calls for more power to drive the pile to the required depth.
Epoxy coatings can also be used to shield the steel screw piles from corrosion. Epoxy coatings are generally affordable. However, care must be taken to use a formulation that will have a service life that matches the service life of the screw piles. The epoxy coating can be damaged as the pile is driven into the ground. This damage can cause parts of the screw pile to remain vulnerable to corrosion. The application of the coating can also consume lots of time because the manufacturer often has to ship the piles to another facility where they can be coated.
Use of Thicker Piles
One may also decide to install screw piles that are thicker than necessary in order to account for the anticipated corrosion that will take place during the service life of those piles. Thus, the piles will remain structurally sound despite the corrosion that they suffer. Two issues immediately come to mind when this approach is considered. First, soil conditions can alter so much within the service life of the piles that it is hard to predict with any degree of certainty how much the piles will corrode in their lifetime. Secondly, it is often necessary to pair this protection measure with a secondary measure so that corrosion is slowed down. This additional mechanism increases the total cost of the project.
As you can see, each protection method has its own unique benefits and drawbacks. Your best chance of adequate protection therefore lies in involving a steel screw pile expert in the selection of the best pile-protection method for your location.