How to Pour New Concrete Over Old Concrete on a Garage Floor
Concrete is a long lasting, durable building material, but even the best laid concrete slabs can begin to show the signs of age. The slab of old concrete in your garage may be dulled and gouged. It may have chips in the surface, or even develop small cracks, but as long as it's still somewhat intact you can extend the life of that old concrete by resurfacing it with a new layer of sand-mix concrete. Does this Spark an idea?
Things You'll Need
- Power washer
- Spade
- Respirator
- Safety goggles
- Saw
- Crack chaser blade
- Putty knife
- Epoxy gel adhesive
- Joint repair sealant
- Concrete grinder
- Bonding adhesive
- Sand-mix concrete
- Screed board
- Wood float
- Sealant
Instructions
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1
Clean the surface of the concrete completely. A power washer rented from a local equipment rental shop can help remove oils or other spills which may interfere with the new materials to be placed on the surface.
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Put the respirator and safety goggles on, and then repair any cracks that may be present in the concrete. Route the cracks out from the surface with a crack chaser blade, opening the crack to a depth of between ¾ to 1 inch. Use the blade to make the side surfaces of the crack vertical. Wash the crack out with water and wait for it to dry. When the crack has dried, use a putty knife to place a coating of epoxy gel adhesive on the surfaces of the crack, and allow the gel to dry. Finally, fill the crack with joint repair sealant.
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3
Profile the concrete surface in preparation for the bonding adhesive. Profiling the concrete requires that you create a texture for the bond to adhere to. This can be done using a mechanical concrete grinder. Begin in the corner of the garage and walk the grinder over the floor surface, lightly scratching the entire concrete slab. When you've completely textured the surface, use a broom to remove all the dust created from the process.
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Apply a layer of bonding adhesive over the slab according to the manufacturer's instructions. The bonding adhesive will help the two pieces of concrete stick and move together, as well as prevent water from seeping between the materials, causing damage.
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Mix a batch of sand-mix concrete. The mixture should have a consistency that's a bit thicker than normal concrete. Spread the mixture onto the slab, firming packing the new layer. Make the layer about 1 inch thick for best results.
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Smooth and level the surface of the new concrete with a screed board, a wooden 2x4 with handles attached, to smooth. Then, float the surface using a wood float, a Mason's trowel with wooden blade, using a back and forth motion to level the surface.
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Cut control joints in the new concrete in the same locations as the old ones. Cover the surface with a plastic sheet and then allow the new concrete to cure completely. Once cured, apply a sealant to protect the new surface and to make cleaning easier.
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Tips & Warnings
Lay the new concrete surface in cool weather with temperatures between 50 to 60 degrees Fahrenheit.
