my first post - and it's kind of a doozy so here goes.
i'm interested in building an above ground cement hot tub and am just beg. the process of research. i had seen one a couple of years ago that basically looks like cinder blocks stacked up and then covered w/ cement. i know that's probably over-simplifying the situation (by a long shot) but, it seems to me that if designed right that could be a possibility. i know there would probably have to be special concrete involved, etc. but has anyone ever seen something like this done?
I live in coal mining country and the underground miners tell me of a product called Block Bond that is a cement, reinforced with fiberglass. They stack concrete blocks dry and trowell this product on the joints and they tell me you will destroy the blocks trying to get them apart.
I don't know how widely the Block Bond is sold but if you could get it where you are, you could dry stack the blocks and plaster both sides with it and have a nice hot tub.
Block bond or a similar product could be used if you do not have to fight the expansion from freezing and thawing and you want a square tub with internally reinforced corners.
If you want a contoured tub, you will need the fill the wide vertical joints with mortar to accept the thin skim coat of the surface bonding material.
The material also has to be applied to both sides of the wall and the wall must be anchored all around like in a mine. In some mines, the surface bonding (Block Bond, etc.) is applied to only one side because of construction limitations and the need to protect only one face.
The trick I think is it needs to be insulated on the outside of the tub. The interior of the tub could be concrete , then insulate the exterior and underneath with rigid foam. If you insulate the interior there is no way to bond anything. Unless you where to do a layer of wire mesh on the inside and skim coat that with a lightweight concrete, then the newer fiberglass mesh and bond. Just spitballin here...
Well mudmixer, you are a concrete guy, how would you build one if a customer asked? This question is for all those concrete guys actually.
Me , I would use an old clawfoot bathtub, outside, and fill it with warm water when I need to relax. Then just pull the plug when your done.....and wrap up that frozen hose you just used to fill it.