Steel screw piles are one of the most popular construction products used for building deep foundations today. In most applications, corrosion of the steel is not a serious concern, but if the soil into which the piles are going to be driven is corrosive in nature, measures will have to be taken to prevent rapid degradation of the portion that is below the ground.
Fabricators of steel screw piles can provide products with that can offer maximum resistance from soil corrosion. Here's are some options for minimising the impact of corrosive soils on steel screw piling:
Coating steel substrate with zinc is one of the most effective ways of extending pile lifespan in corrosive soils. There are many different methods of applying zinc coatings to steel screw piles, including hot-dipped galvanising, electroplating and thermal spraying. Zinc offers superior corrosion resistance compared to steel, and therefore acts as a sacrificial anode.
In metal coating applications, a sacrificial anode is a highly active metal (zinc) used to prevent corrosion of a less active metal (steel). When zinc-coated steel screw piles come into contact with corrosive soils, the zinc will corrode before the steel substrate does.
A major downside of zinc coatings is that they will eventually corrode when used in corrosive soils, so they are recommended for buildings that are expected to stand for several years. When used in corrosive soils, zinc-coated steel screw piles may only be ideal for building temporary structures.
Protective paint coatings can also be used to prevent the corrosion of steel screw piles used in corrosive soils. There are several types of paint products that can be used, including standard paints, epoxies and coal tar. As not all paint protection systems are equal in terms of effectiveness, the cost of these paint coatings varies greatly.
When choosing an anti-corrosion product for your piling application, make sure the paint coating is thick and resilient enough to keep the pile in good structural condition for its entire life. The use of paint-coated steel screw piles might not be ideal where the piles will need to be driven through dense layers of rock-hard soils. This is because the paint coatings may become peeled off as the piles are being screwed into the ground.
Before you can use steel screw piles for your deep foundation building applications, make sure you consult a soil engineer to help you accurately assess soil characteristics and conditions. That way, you will be able to select a product that offers the desired level of protection from soil corrosion.