When should I start floating concrete?
Float the concrete when you're done grooving and edging (Photo 6). Floating removes the marks left by edging and brings the surface one step closer to a final finish. You may have to bear down on the float if the concrete is starting to harden.
How long do you wait to trowel concrete?
Depending on the humidity, temperature and wind condition, you may have to wait anywhere from 30 minutes to 5 or 6 hours. Once all the water has bled out, you can take out the steel finishing trowel. The new concrete surface is ready for the final touches.
How long do you wait to bull float concrete?
Darbying or bull floating should be done immediately after "screeding", or after the concrete has been tamped if tamping was done. This process should be finished before excess moisture or bleedwater appear on the surface.
More often, premature finishing or improper first (bull floating) or second floating results in trapping rising bleed water and air below the top surface of the concrete (Image 2). When this occurs, the resulting weak or soft zone below the surface causes the top surface of the concrete to flake or scale off.
Power trowels are typically used when concrete slabs are too large to be finished by hand trowels.
Push the bull float in one direction only across the concrete, keeping its front edge slightly above the surface by raising or lowering the handle. Two or three times is enough. Don't overwork the concrete or you'll weaken it by drawing too much sand and cement to the surface.
Purpose: Used after floating to produce a smooth, hard, dense slab surface. What's available: Steel trowels look similar to hand floats, except the blades are thinner and the handles are open rather than closed. The key difference among tools is the type of steel used for the blade.
Sand the Surface and Wash the Concrete
Finish by fine-tuning with light sandpaper, until the surface is perfectly smooth. We recommend using a hand planer to smooth and compact the surface. If the concrete dries a lot then we recommend that you add water to the surface, this will help you give it a good finish.
If the rain occurs when the concrete is fresh (about 2-4 hours after mixing), the surface should be protected from the rain. If the concrete has stiffened to the point where it is ready for grooving and grinding (typically 4-8 hours after mixing), damage due to rain is usually no longer a concern.
Your concrete should be solid enough to walk on, without leaving footprints, after anything from 24 to 48 hours. By seven days, your concrete should be cured to at least 70 percent of its full strength.
A broom finish can stand up well to the elements, even without being sealed. Because of this, we recommend that you seal broom-finished concrete so it maintains its intended look. Ask us about spicing up your broom-finished concrete with borders, broomed-in patterns, or even acid or dye staining.
If you haven't done this before or only done it a few times you are likely to make two mistakes; troweling too soon and troweling too much. Both of these have the effect of pulling fines and water to the surface. This can lead to a weakened surface, tiny cracks and a white dusty surface.
Dusting Concrete Surface. Formation of loose powder resulting from disintegration of surface of hardened concrete is called dusting or chalking. The characteristics of such surfaces are: They powder under any kind of traffic. They can be easily scratched with a nail or even by sweeping.
Trowel-finished concrete floors are seamless surfaces that recreate the concrete effect. Thanks to some specific treatments, trowel concrete guarantees a high resistance to abrasion, wear, chemical agents, weather conditions and water penetration. It is also easy and quick to clean.
A power float is a hand-operated machine used to produce a smooth, dense and level surface finish to insitu concrete beds. Power floating eliminates the time and materials needed to apply a finishing screed and is quicker and less labour-intensive process than hand trowelling.
The concrete helicopter must be used before the poured concrete has completely dried. However, if the concrete is too fresh and wet, using the concrete helicopter may cause delamination of the material and concrete will be torn up.
How Long Does Concrete Take to Dry Before Rain? Even if it starts raining after a concrete pour, the potential for damage may not be that serious. If you had time to complete the finishing process and the concrete has stiffened (typically 4 to 8 hours after mixing), rainwater may cause little if any damage.
If you expect to pour concrete and use it in a couple days, you can't. Protect new concrete from the cold for the first two to three days—up to a week, if it's very cold—after which it should be strong enough to handle it without risk of damage.
Walls and columns can be removed after about 24-48 hours. Slabs, with their props left under them, can typically be removed after 3-4 days. Soffits, with their props left under them, can be removed after one week. Props supporting slabs under 15 feet can be removed after one week.
Magnesium smooths the surface of fresh concrete and opens the pores for proper evaporation, all without pulling the surface like a wood or resin tool. Extruded floats are made by pushing molten magnesium through a die (think Play-Doh), so the floats are the same profile from end to end.
What it is: The fresno may look similar to the bull float, but its blade is made of tempered or “blue” steel. The fresno should only be used following the bull float. Purpose: The fresno is applied after the bull float to better seal the surface of the slab.
Fresnos are used for troweling slabs that do not require a hard trowel surface. A Fresnos will speed up the troweling process. Fresnos should not be used as bull floats. Troweling can also be accomplished by machine.
A small trowel used to spread mortar on a brick before it is laid.
Trowel Finishing Concrete
A power trowel consists of one or multiple rotating blades enclosed by a safety cage. This type of concrete finishing equipment is used to create a polished, level finish on a variety of concrete surfaces. Floating, finishing, and combination blades are used to create the desired end result.
For this, you need to put a small amount of elbow grease on the area and sprinkle baking soda over it. Then use a damp cloth to rub around the area to make the area smooth and shiny again. Most of the time, you will be needing to follow this technique to make the concrete surface look shiny and smooth.
A concrete float is a tool used to finish a concrete surface by making it smooth. A float is used after the surface has been made level using a screed. In addition to removing surface imperfections, floating will compact the concrete as preparation for further steps.
You can put new concrete over old concrete. However, unresolved issues with your old concrete, such as cracks or frost heaves, will carry over to your new concrete if not taken care of. In addition, you must pour it at least 2 inches thick.
After 24 hours, you can walk on your newly poured concrete, but avoid dragging your feet, 'doing the twist', or allowing your pets to walk on it as their claws can scuff the concrete.
Some mix designs reach 5,000 psi of compressive strength in seven days – or even in 24 hours. However, the faster concrete reaches the minimum design compressive strength, the greater the cost of the concrete.
In standard industrial cases, full strength concrete is recognized at 28 days. At seven days, you should have concrete that is cured to 70% full strength or greater. But to answer the question of, “How long does concrete take to set?” concrete setting time is generally 24 to 48 hours.
ANSWER: Keeping concrete moist helps the curing process. If too much water is lost from the concrete through evaporation, the hardening process slows down or ceases. Concrete continues to gain strength after pouring for as long as it retains moisture, but the longer it moist-cures, the slower the rate of strength gain.
Fresh concrete is always much darker than when it is fully cured and dry. Even uncolored concrete. Wait at least 7 to 10 days until the new concrete has hardened and dried. If the concrete is on a wet subgrade or there's underground water, it may stay dark for as long as it's wet.