Aluminum in Non-Shrink Grout

[JedClampett]

Our specifications prohibit the use of aluminum in non shrink grout. As far as I can tell, none of the major manufacturers use it and they're very clear in their data sheets that aluminum is not contained in their grout.
My question is: Was there a time when aluminum was commonly used in non shrink grout and why was it stopped? We have some corrosion at a grout steel interface and I'm wondering if a grout with aluminum in it caused the problem. The project was built in the very early 80's.
Is there something else that might be in grout that might cause corrosion? This is a common detail for us and I've never seen corrosion before, even on much older work. There was a case where there was a calcium chloride admixture added that corroded pre-stressing strands and caused a bridge collapse about 20 years ago, but I don't think using it was common.

 

[dik]

The reaction of the aluminum powder with the alkalai caused the non-shrink grout to expand slightly... It was an early fix... like adding calcium chloride to concrete mixes...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[hokie66]

Yes, aluminum powder was a part of earlier non-shrink grouts. But I don't know when, or why it was stopped. As to calcium chloride in concrete, that was unfortunately widespread in cold climate concreting as an accelerant.

 

[JedClampett]

Well, this is in Tempe, Arizona, so we don't need many accelerants.
I've got a call into a couple of grout manufacturers about the effect and cessation of aluminum in grout.

 

[dik]

Jed... I'm not aware of it being used anymore... they have other agents...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[NorthCivil]

aluminum and steel are only mildly incompatible (practically) anyway. I'm not sure of the level of corrosion you are witnessing, but aluminum powder in a grout would likely be less incompatible than aluminum in direct contact with steel.

 

[dik]

It's the alkali in the grout that causes the aluminum to 'bubble' and swell... making it non-shrink.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik