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After reading the article a while back on cast concrete countertops, I was convinced that was the way to go when I’m ready to remodel my kitchen. In the meantime, I am building a set of end tables and would like to cast concrete tops for them. Being relatively new to concrete work, I need some advice.
I am planning on casting them in plywood forms, topside down. Besides vibrating the form, what can I do to keep voids from forming? How fluid should the mix be? Does a small cast (less than 24″ square) need any kind of reinforcement? I am assuming that I will need to turn the slab out of the form and do some final touch-up before the concrete is completely set. How long should I wait to do that?
I appreciate any info anyone might have. Thanks,
Bart
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I'd cover the plywood with laminate ...will give you a much smoother surface. Ease the corners in the form with a thin bead of silicone caulk smoothed with a finger; the slightly rounded edge will reduce/ eliminate chips. Reveals can be done with wood strips nailed to the form. Taper the strips so they're easier to remove and caulk where they meet the form. Use form release. Definitely use reinforcement- the type depends on the thickness of the piece. For very thin pieces, use welded wire mesh. If there's sufficient thickness, rebar around the perimeter and mesh may work. Don't add too much water to mix (it greatly reduces strength); proper vibration is the key to a good finish. Set aside some of mix minus the aggregate before you add water. Bugholes can be bagged by adding a little water to the mix you set aside to make a paste. Use a damp piece of burlap (a grout float works well, too) and rub the paste in the bugholes. If you do a decent job of vibration, you shouldn't have many. Color can be added to your concrete mix. http://www.solomoncolors.com/ is one source ...there are others. Concrete has many possibilities. Have fun.
*Bart, If the email address you gave is good, expect an incoming file from me.Good luck...Mongo
*If you don't like to use silicone for corners use some cheap plastic wraped molding mitered into the corners to make a decorative edge when turned out.
*I've been toying with the idea of using concrete for a few things too, especially creating blocks for walkways. Some questions:Could you just line the 'box' with black plastic instead of laminate?What's the best concrete mix to use?What do you use for vibration?Any book recommendations?Your example looks great! Inspiring!Thanks,steve
*b WBA At Your ServiceAny bubbles beneath the black plastic will leave voids in the finished surface.Typical Sakrete bag mix with the 1/2" stones works well.Vibration can be done by tapping with a hammer or using a palm sander with no sandpaper installed.
*Ditto Tim's comments.
*You can use plastic sheet( visqueen) if you pull it tight under an inverted mold box. It will add a smooth surface to the finished side . If you mix sand and gravel then put your visqueen mold over that it will give an interesting texture to your stepping stones . Experiment a little.
*Bart, we cast stain glass stepping stone and this top sounds like a larger version of what we do. If you want to have some fun, have a stain glass shop cut out some pattern you like and cast it in the top.The pattern can be stuck on clear self adhesive shelf paper with 3/16" grout lines between the pieces of glass. The contact paper is then laid in the bottom of the form and grout added about 3/4 to 1" over it, followed by the concrete, reinforcing, etc. When the pour has curred and you remove it from the form, peel the contact paper off,gout any air holes in the face and seal the top/ side only.You will have a set of end tables that will be real conversation pieces. I have made a couple of small plant stands using the stepping stone as tops. They are real big ooh! and ah! items.Just a thought.Dave
*Dave, I'm not real familiar with stained glass work, so what kind of grout are you talking about? That sounds like a great idea.Bart
*Lots of info out there on making concrete countertops, including several past posts on Breaktime:http://www.taunton.com/fh/features/techniques/41smooth.htmhttp://webx.taunton.com/Webx?128@@.efe8b35http://www.naturalhandyman.com/iip/inf/author/dcn/conccounter-a.shtmhttp://www.pcinews.com/concrete/00con4fa/concotop/counter.htmhttp://www.canadianhomeworkshop.com/countertop.htmlhttp://www.concretenetwork.com/concrete/countertops/There are probably many more if do a little searching.
*Casey,I just wanted to say that I like the way that you do that, and you don't turn it into an insult.
*Bart, acctualy grout is probably the wrong word, but that is what they call the stuff that goes betweeen the pieces of glass or tile in a mosaic. The grout in this case is mortar mix like you lay block or brick with.We use Sakrite mortar mix and concret mix for our stepping stones. I usually enrich the mix just a little by adding some Kosmortar to the grout and portland cement to the concrete. I do this beause I feel the bag mix products are a little long on sand and short on cement.I'll try to get DW to get me a photo of one of her stepping stones.Dave
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After reading the article a while back on cast concrete countertops, I was convinced that was the way to go when I'm ready to remodel my kitchen. In the meantime, I am building a set of end tables and would like to cast concrete tops for them. Being relatively new to concrete work, I need some advice.
I am planning on casting them in plywood forms, topside down. Besides vibrating the form, what can I do to keep voids from forming? How fluid should the mix be? Does a small cast (less than 24" square) need any kind of reinforcement? I am assuming that I will need to turn the slab out of the form and do some final touch-up before the concrete is completely set. How long should I wait to do that?
I appreciate any info anyone might have. Thanks,
Bart