The Lifespan of Screw Pile Foundations

A common question asked about ground screws is;

how long do ground screws and screw piles last as a foundation solution?

The life expectancy of our ground screws is calculated on the typical corrosion rates of galvanising and steel, combined with the high-quality manufacturing process of all our products at RADIX.

The average corrosion rate of the zinc coating on galvanised steel is 6µm per year in typical soil conditions, as provided and verified by independent engineers. Based on RDX PRO Ground Screws* being galvanised to 85µm and forming a layer of protection against the elements, we can show 85 / 6 = 14 years.

Once total corrosion of the zinc coating is accomplished, steel corrosion then commences at an average rate of 30µm per year.

Again, based on our RADIX PRO Ground Screws having a 3.0mm thick helix, this would take 60.6 years to reduce to a 1.0mm thickness.

The ground screw 15x3 helix is checked with 50% of the 70kN test load to represent the FOS of 2 we adopt at RADIX and, as illustrated below, a reduction to 1.0mm is still within the parameters of a safe working load.