Aircrete

[LeonhardEuler]

This post is just for fun. (Not a project im working on).

I've been seeing people build small structures on youtube out of this product called aircrete that is concrete mixed with foam, obviously its intention is to leave air voids in the concrete after curing. I looked up the product data and the aircrete weighs ~30pcf and has a 300psi compressive strength. It got me thinking.. Could this stuff be used as a structural material? Specifically could it be used for a flat roof. It is very light and the compressive strength is not as necessary for flexure as enough bars can be put in to take the flexural force. What would be the limiting factor?

I ran through a flexural calculation and found that you could span 30' with a 200kip-ft max moment with a couple #4 bars top and bottom. It also seems that it should be plenty heavy enough against hurricane uplift. Surely there is a reason that it could not be used, but I can't think up one.

I realize even you could do you probably wouldn't want to as it is probably a more expensive process than pouring in place, but again it is just for fun.

Discuss!

 

[Ron]

Already been done many times. It is cellular concrete. Has many uses for roof deck and geotechnical fill. Not very good for structural applications but could be done with enough care. Expensive.

Similar is aerated, autoclaved concrete made in blocks and panels. Strong and has potential for more structural applications. Did an evaluation of a condominium built with this material about 10 years ago.

 

[BridgeSmith]

I would think reinforcing it effectively would be difficult, due to the much reduced bond strength. The lap for a #4 bar would have to be 8 or 10 ft, wouldn't it?

 

[LeonhardEuler]

HotRod10I figured there would be a similar variable that would not allow it to work. Of course you could just run the bar the full 30 ft and would be fine in that regard.

 

[BridgeSmith]

LeonhardEuler, I'm still not convinced that the analysis that works for regular concrete with a 20:1 strength ratio still works with a 200:1 strength ratio. Would the height of the deformations of standard rebar be adequate, or would the low strength material just crush around the bar everywhere. Remember, it's not just lap length that would be increased by a huge factor, the development length theoretically would be also. I suspect reinforcing it with rebar or even wire fabric would be a useless gesture. Possibly, it could be reinforced with a geosynthetic (nylon, vinyl, or PE strips), or maybe a knotted piece of rope.

 

[dik]

What surprises me is the high relative cost for aircrete, foamcrete, or CLSM...

Dik