How to fix aluminium posts welded onto concrete slab?

Faydent

I mounted a number of alum posts with welded baseplates onto a good concrete slab.  Indoors.  After a while the base plate rose and popped the nuts off.  Upon inspection the whole anchor was crumbling away.  I'm thinking it is a metal on metal problem but noone on the internet  seems to mention it or give a different solution  to useing anchor bolts. Photo is of one of the better ones.   I cleaned the others up before thinking of taking photos. Please help.

JacobZ

Hi @Faydent,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Do you know what coating the anchors you've used had on them? Were the anchors still relatively intact?

Is moisture present around the base of the posts?

Aluminium is susceptible to galvanic corrosion when in contact with more noble metals (like steel) and an electrolyte (moisture, for example). If the post base is in contact with steel anchors, and moisture is present, this can create a galvanic cell, leading to corrosion.

I suggest using stainless steel anchors such as these Ramset 10 x 50mm Stainless Steel DynaBolt Plus Hex Nut Bolt as they are far more corrosion resistant.

Let me know if you have any further questions.

Jacob