A concrete countertop can be a great addition to your kitchen or bathroom. Strong and durable, these countertops can last the lifetime of your home with little maintenance necessary to preserve their good looks. You can mix recycled glass into the countertop during the building process for a look that's different than traditional concrete countertops. The glass reflects light from the surface of the countertop, giving the concrete an ever-shifting appearance that you can modify by using multiple-coloured glass. It's a way to build a countertop with visual impact while saving money on the counter itself and being environmentally friendly.
Assemble the mould for your countertop. You can purchase countertop moulds to fit most cabinets from a home improvement store. Assemble the moulds by screwing the sides and bottom together using wood screws. Seal the seams in the mould with silicone to create smooth edges to your countertops.
Attach foam inserts to the bottom of the mould cut with a utility knife into the shape and size of any faucets or sinks that require holes in the countertops. Make sure the inserts extend the total height of the countertop so that the hole will extend through the countertop, and secure them in place using the silicone. Cut steel reinforcing mesh with wire cutters to the size of the countertop, extending to within 1/2 inch of the countertop edges, with holes created in the mesh for the foam inserts. Set the mesh aside for later use.
Mix the concrete for the countertop according to the manufacturer's instructions. Use an electric drill with a mixer attachment for the concrete and add the recycled glass to the mix in a large bucket. Substitute the glass pieces for an equal amount of gravel contained in the concrete mix. Mix the glass thoroughly throughout the concrete mix for an even dispersal.
Pour the concrete and glass mix into the mould, filling it to the halfway mark. Spread the mixture evenly throughout the mould using a trowel, making sure to fill all corners of the mould. Tap the sides of the mould with a rubber headed mallet to help the concrete settle into place and to move any air bubbles created by the pouring towards the top. Allow the concrete to sit for 10 minutes, firming up slightly.
Place the reinforcing mesh onto the settled concrete. Pour the remainder of the mould full with the concrete and glass mix, using the trowel to spread it evenly throughout the mould. Tap the sides with the mallet to remove air bubbles. Use a piece of wood to screed the top of the concrete, removing any excess concrete from the mould and evening out the surface. Allow the concrete to cure for one week.
Remove the screws from the mould and remove the wood from the concrete. Turn the countertop over and place it onto a flat surface, topside up.
Sand the surface of the concrete countertop with a wet sander equipped with diamond embedded grinding pads, getting both the top of the countertop, as well as the sides. Sand the surface smooth, removing any roughness and revealing the embedded recycled glass pieces. Change the sandpaper in the sander after completing a run over the countertop, switching to a finer grit of sandpaper each time, beginning with 50-grit and ending with 3,000-grit. With each run, smooth the surface further until you reach the finish you desire. Make sure the countertop is smooth to the touch and that the glass is easily visible and even with the surrounding surface.
Seal the concrete surface with concrete sealant to protect the surface from water damage or staining. Brush the sealant onto the countertop using a foam applicator. Allow the sealant to dry overnight before mounting the finished countertop to the cabinet.
Wear protective gloves, safety goggles and a face mask during the building project to protect from hazardous materials and glass powder.