My husband and I have a design for outdoor seating we would like to create that is organic (curvy) in shape and surfaced in mosaic designs. Think of a dragon undulating in and out of the water, the part that appears above the water's surface would be something like what we want to create.
I have experience using chicken wire as an armature under plaster and I know this degrades with use – the bendy nature of the armature causes the plaster to break. I don't have experience with concrete but I suspect it would be likely to degrade in the same way. Is there a way to improve the plasticity of concrete? Is there a particularly good way to create an organic form, or should the seating be solid concrete?
Is fiberglass a better choice?
Best Answer
Concrete will definitely be strong enough if done right.
Make sure you use the right mix. I would use sakrete 5000 plus, NOT quikcrete 5000, and add a hand full of Portland cement to better hold the mosaic. Then add superplasticizers. More water is bad, but you want it to flow into an odd shaped mold and around mosaic tiles, superplasticizers will solve this. You can get this at http://www.expressions-ltd.com/default.asp You can get some integral coloring for the concrete there too.
The forms will be tricky, but i think i would build a wood box and drape some cloth in it the way you want. Then spread some glue on it to stiffen it up. Then use bondo and sand it down to smooth. Then you can use some spray adhesive or silicone to put your mosaic tiles in upside down.
You are going to need to vibrate it after you pour it. Maybe just hammer on the wood box.
I am saying this would be solid concrete, but this will be very heavy when you demold it. You could put something lighter in the mix after you pour it, maybe some empty bottles?
Anyway, yes, this can be done with concrete. Concrete would be very strong, and no you don't need mesh in this setting. The tensile strength of concrete is terrible but the compressive strength is amazing.