However, it is essential to wait until it disappears. Working the concrete before the “purge water” disappears from the surface will weaken the slab surface when it dries. When all traces of the water have disappeared and the concrete begins to harden, you can resume finishing activities. There is no room for guesswork in the mixing process.
Using the right amount of water and exact measurements are crucial steps to achieving the right strength and the best possible finish. The broom finish is what you find on the sidewalk when you walk around your neighborhood. This finish simply has a broom that runs across the top of the concrete while the concrete is still slightly damp, to give it a non-slip textured finish. Broom finishes are generally applied to outdoor concrete (with built-in air) that will be exposed to the elements.
The hard trowel finish can be found in the garage of your own home, as well as on the floors of large commercial buildings such as Wal-Mart or Costco. This finish takes longer than the broom finish due to the need to make multiple passes with a steel trowel along the slab surface. Both manual trowels and trowel machines are used to give concrete a smooth and smooth finish in this scenario. However, stamped concrete achieves a highly aesthetic appearance that is perfect for applications such as outdoor patios.
You can use the light foot traffic concrete 3 to 4 days after placement, and you can drive and park on the concrete after 5 to 7 days, but curing is not complete until 28 days. Then use an edge tool to sort the edges and corners of the concrete by moving it back and forth, as this will make the concrete more durable. For a crisp, even texture, keep the bristles clean by removing excess concrete as you go. Once the concrete is fully cured, apply a protective sealant to prevent staining and extend the life of the slab.
Finish cutting slots at intervals in the concrete before it dries to reduce the risk of future cracking. Use the “fingerprint” test to make sure the slab is hard enough; you should be able to press on the concrete about ¼, but no more, when the slab is ready. Fixed-head floats require the finish to lower the handle, thus lifting the front of the blade as you push it across the surface, then you must lift the handle to lift the other side of the blade on return. By turning the handle, the finisher can raise and lower the blade, allowing the finisher to go much further.
Once the surface has been floated or troweled, test a small section to see if the concrete has hardened enough to give it the texture you want. To make a grooved joint, simply place the grooving tool in the concrete and then push the groover while applying pressure to the trailing edge. If you are using wheelbarrows to move concrete from the truck to the forms, make sure you have enough help to finish the project in a timely manner. Try to move quickly, except where otherwise noted, so you can finish before the concrete dries, especially on a hot day.
Gravel concrete finishes require a completely different mix design that typically consists of 50% sand and 50% gravel.