Here's the pics! Started with the base Mold made out of 3/4 inch melamine and 3 layers of 1/4 inch masonite for the curves
Two layers of 3/4 inch plywood cut to shape lined with 3 layers of 1/4 masonite Sides of form are 3/4 inch masonite over the 3/8 plywood base, the base will stay permanently, the masonite underneath will be removed so no wood will show. Rebar and wire mesh for extra strength on the 12" overhang Time to add some concrete! Mash it into all corners and crevices with your hands Looks pretty dry! Add some nicely colored aggregate into the surface and hope they show up when polishing! Doesn't look so dry anymore does it! Cover and let it cure slowly!
I have plans for concrete counter tops in my own house, and have seen reference made to the Quickrete countertop mix. Was sent an article on www.familyhandyman.com that descrive using Quickrete Precision Grout or Sakcrete Construction Grout instead. Anyone else heard of or tried this?
Can't wait to see the finished product. You may have planted a seed, my kitchen could use new countertops.
from the pics, it looked as if the rebar/grid is close to the top surface(if not actually laying on it) what measures did you use to keep it off?--i couldn't see any provisions, althought i do miss stuff and hope i'm wrong! other wise it looks like you (and work mates) did a beautiful job
It's two inches thick, all of the rebar and wire are at least one inch from the surface, hold down with screws into the underlayment.
Honestly, I hope it turns out. Concrete is a very difficult and complicated material to work with and it takes a lot of practice to make it look decent. I took a couple concrete formwork classes and the biggest problems we had were: 1. Form release (didn't use oil, wax, etc.) 2. No Chamfered edges. You need to place a chamfer on the edges either by forming or by trowel. 3. Rebar/reinforcement height. Set the rebar on "legs" to get the proper height off the bottom. Choose the proper size reinforcement, making sure that it doesn't protrude past specified distance from edge of forms or surface of pour. Reinforcement goes on the top edge, not the bottom edge of a pour. 4. Not enough vibration results in honeycombing 5. No taping/closing off edges causes the concrete to seep through and "burr" (push through screws in the forms, etc.) 6. Be sure enough reinforcement (most of the time looks very excessive due to weight of concrete) I'd just pour it on a floor to eliminate the need for a bottom and lots of reinforcement (put plastic underneath). 7. Finishing wet is hard, be sure to chamfer edges and "pull" water/cement out of the mix to the surface, add in concrete in low spots. Basically instead of grinding the shit out of the concrete, making a big mess and exposing mesh/rebar/other mistakes, just be sure to wet finish it with a trowel. If the concrete doesn't have enough water at the surface, take the trowel and "pull" water up by pushing up and down slightly creating suction to draw water/cement to the surface. If needed, spray a very light film of water over the surface to assist in pulling, possibly use a screed (that long trowel with a pole attached to it). Or if you are going for exposed aggregate, the concrete can be washed away, but would leave an uneven surface (nice for sidewalks, walls, etc.) This is how people get that smooth finish on countertops. If I were to pour countertops (and not that I have and good on you for going for it) I would pour on the floor, make it very, very simple (square not rounded). I would use a greater depth pour, it looks like you are going to have issues with reinforcement coming through on the finish work, possibly only use mesh (4000 psi sidewalks only use mesh).
No more complicated or difficult than any other construction material. As finish carpenter, I find it much more forgiving than wood. He said underlayment, not formwork. Big difference.
