Is anyone familiar with a claimed interaction between concrete and new aluminum forms?
I have seen a claim by a concrete contractor that when new alum forms are used the first several times a gas is created which creates a “an unappealing wall appearance” but does not harm the concrete’s strength.
I’ll be seeing some tomorrow, I’m told, and am looking for more info.
I don’t know about yours, but my church isn’t a hotel for the holy, it’s a hospital for sinners
Replies
Bob,
The only thing I can think of that would happen is that the by product of the corrosion that may occur may be left on the surface of the concrete.
I'm guessing that once the form have a protective layer of oxidation, they will no longer produce this effect.
Are you looking at this as a result of a dispute?
I think Brownbag is one of the concrete experts here.
Good luck.
Eric
I Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
concrete and aluminum does make a chemical reaction. But the new forms are not aluminum, they maganese. Nothing made for concrete is made out of aluminum.
Another inspector I work with inspected new construction in 2001. He saw "damage" to the foundation surface:
"Foundation walls interior surface shows considerable deterioration. An expert opinion [remember HI's are generalists] will be necessary to determine if there is any compromise beyond the visible surface areas to these walls."
He also raised a question about adhesion of the damp proofing.
The contractor wrote:
"when new Aluminum Forms are used the first couple of times te lime in the concrete reacts with the aluminum face of the form. This rewaction causes a gas. This gas then escapes upward along the form. While this reaction creates an unappelaing appearnace, it has been found over several decades of experience that this reaction does not adversly affect the strength of the concrete wall."
And a professional engineeer wrote:
"The concern was based on the film left on the wall from the forms. In our opinion, the exterior damp proofing is sufficiently adhered to the wall and the quality of the concrete is acceptable for all anticipated loads."
I'll try to get some pics of the walls and post 'em.
I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace
Some pics - large and small.
The surface damage wasn't easy to get pics of, the arrows try to highlight the surface damage.
The "erosion was maybe 1/4" deep at the most, and the claimed gas wandered its way along random routes on the face of the "brickface" poured concrete.
(Boy, that brick face pattern really fools me! At least one step up from wood grain in vinyl siding!!!)
I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace