Hold down bolts with acidic adhesive

[pwht1]

Could someone please provide a reference to some literature or advice on the use of acidic/low pH epoxies in concrete to anchor steel bolts.

On a project currently under construction the builder wanted to use a different epoxy to the one I had specified. According to the manufacturer (They contacted me and I reviewed their technical data) the proposed epoxy met all of the structural load requirements, thus I approved its use. That was 2 weeks ago, today I was reviewing some of the manufacturers data sheets (just to fill in some time) when I stumbled across the corrosion report and it had an acidic pH. I'm a little concerned as the building is also in a coastal environment and there are high uplift loads under wind action.

Any advice would be appreciated.

Thanks,
Paul

 

[Ron]

Epoxy adhesives for concrete anchors have been around a long time. In most cases, once catalyzation occurs, the materials are fairly inert, though some have more resistance to certain chemicals than others.

 

[MintJulep]

And what is the pH of the the epoxy that you originally specified?

I'm pretty sure that pH only has meaning for liquids. So once the components catalyze and you have a solid, acidic is meaningless.

 

[hokie66]

I don't know about the epoxy, but pH does have meaning for solids. The chemical process of carbonation lowers the pH of concrete. Once the pH falls below about 10, the concrete is no longer capable of protecting the reinforcement against corrosion.

 

[cloa]

Pure solids are slow to react so their acid or base potential is hard to realise some electrolytic fluid not necessary water is generally needed to speed the - of course the concrete will contain some moisture and the epoxy will have some slight fluid traces so the reaction may occur.

 

[pwht1]

My chemistry is a little hazy, but doesn't steel protruding from concrete rely on the concrete as a 'sacrificial' corrosion protection or something like that? If the steel is separated from the concrete by an acid won't that then increase the corrosion rate and prevent protection from the concrete?

 

[cloa]

Of course the OP didn't mention steel. Steel is passivated by the concrete by its caustic solution. The expoxy only going to be acidic if there something to make it a solution. Iron III in solution is acidic but add FeCl3 salt to a metal and no reaction.

 

[hokie66]

Correction, cloa...the OP asked about the effect of acidic epoxy on steel anchor bolts in a coastal environment.