At first blush, the idea of making a countertop from concrete has all the appeal of an aluminum bird feeder, or a cast-iron guitar. Isn't it a bit like preparing vegetables on the garage floor? Rolling cookies on the sidewalk? Not at all. First introduced by designers who saw the aesthetic potential and versatility of the material, concrete countertops are fast becoming the answer to homeowners' demands for something new in kitchen (or bathroom) design that doesn't cost $50 per square foot and require experts to install. It is also an open door for new, creative ideas from handy homeowners who want to try something a little different.
A properly done concrete countertop with a little creative input is comparable to the most popular finishes available today. It will be every bit as attractive, smooth and durable as ceramic, natural stones like granite or slate, and solid-surface materials like Corian. And it can be very economical; concrete costs a fraction of those materials. Best of all, you don't need professionals—concrete is a forgiving material that is accessible to any homeowner. Working it requires tools you probably have, and making a mistake means, at worst, you own a couple of bucks' worth of custom-made patio stones.
That's not to imply that concrete doesn't take any skill to install. You have to understand the basics of how concrete reacts as it sets and cures (see "Concrete foundations"). Concrete is heavy and a little messy for someone who is not used to working with it. Luckily we had Bill Loveys from Ardex Engineered Cements on hand to help us through. If you follow Bill's steps, and try mixing and drying a few test squares before diving in, you will discover an opportunity to create a unique and personal countertop that none of the conventional materials can beat.
Finishing in style
Concrete countertops can take a variety of finishes for truly unique, individual looks. It can look like almost anything: natural stone, solid surface, ceramics—even concrete. Test a few finishes on concrete samples before committing yourself on the actual countertop.
Some effects require a slightly more difficult construction method, where the countertop isn't formed in place as we did. Instead, the concrete is poured into a form that's upside down (so the base of the form creates the top surface of the counter). When it's completely cured, the whole form is removed, and the countertop is gingerly lifted in place.
• For a solid colour, use liquid or powder pigment. Mix with the concrete, or sprinkle it on the concrete while it's setting. The advantage of mixing pigments into the concrete is that if the counter chips, the colour goes all the way through.
• You can mix batches of very dry (bread dough consistency) concrete with different colours. Then place the mixes into the form where you want them. To keep the colour from bleeding together, you have to place it, tamp it down, and leave it. For really distinct fields of colour, make the counter upside down, so the surface of the counter remains undisturbed at the bottom of the form.
• For a ceramic tile or terrazzo look, use a grinder with a diamond wheel to cut shallow 1/8" to 1/4" lines after the concrete has cured, then fill in with ceramic grout. Seal the concrete before you grout so the grout doesn't stain the 'tile' surfaces.
• It's easy to embed ceramics, stained glass, terrazzo strips, or almost anything you find in your workshop. Depending on what you want to embed, make this counter upside down also. To ensure the concrete adheres to your additions, use a polymer-modified cement.
• Concrete is porous, so you need to seal it. The choice between topical and penetrating sealers is aesthetic: topical finishes give a glossy not-so-concrete look; penetrating sealer keeps the concrete look but is less stain-resistant.
• The sealer can also be pigmented; another opportunity to change the look.
• Sealant won't stick until the concrete is completely cured. Determine this by laying a piece of plastic on the surface and weighing it down to ensure direct contact with the concrete. If, after 24 hours, there is no dampness collecting under the plastic, the concrete is ready for sealing.
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