It's just suppose to be wall and not load bearing frame.

In a normal construction, there is always the frame then the wall.
I deal with mostly warehouse construction... So it's steel frame and the cladding wall.
You see that cladding don't give any strength at all... It's all the frame that does the carrying.

Is the construction doing something wrong with expecting AAC to hold weight?

We used AAC to make vault as it can be made with fire retardant ability and it's very light, so it's easy to fit those brick into existing building without jeopardizing the floor loading.

Don't blame the brick... Go after the construction or the supplier sales man.

this powered after ageing is like saying steel structure get rusty after ageing. so you ban steel structure ?

you protect the structure from exposure. again i find the problem is people trying to used the product in "ingenious" manner, i call them "chikai" manner.

ACC is done by technically pumping air and creating air chamber [honey comb] in the material hence removing weight/density. the air structure provided "similar" structural strength. take completely solid rod versus a hollow rod. hollow rod is lighter but can also provide same strength as the solid rod ... IFF used correctly.

ACC is lousy at bearing static weight but provide similar impact integrity [you can hit it]. so for your situation, if weight is bare on to the ACC long term ... aka lousy structure, you are asking for trouble. but if the situation is sudden structure break, the ACC would have does it job of preventing total collapse fine.

YES those ACC does go powder. but if you does good wet work [water proof/ air proof] and paint job as you would protect steel structure. i don't really see much of a problem.

I would still chase after the ACC sales guy, what the heck he has promise you? the construction guy, does he know what is he doing with the product ?

I only used ACC for light weight and fire resistance. if its just a ground floor vault where floor loading can take ... i'll go for much cheaper, STANDARD fire brick !!

I have no opinion of those on site easy mix pour in version... never tried them before.

is ACC getting popular ? i still see sand brick trumping everyone in term of total cheapness , sand brick degrade even faster...