Table of Contents
What is the purpose of bull floating?
The purpose of darbying or bull floating concrete is to level ridges and fill voids left by the screeding operation. It should also slightly embed the coarse aggregate to make subsequent finishing operations easier.
Why is it called a bull float?
Probably takes its name from the definition of bull—to make one’s way with driving force (Webster’s New World Dictionary). Spend a few minutes on a hot day smoothing concrete with a bull float, and you’ll get the idea.
Can you finish concrete without a bull float?
You do not need to wait for bleed water to evaporate on the first pass of the Bull Float or Darbie. On some slabs all that may be required is one pass of the bull float; however on most slabs additional finishing will be required.
What is a bull float in construction terms?
What it is: The bull float is a magnesium blade that is initially run across the surface of the slab in the finishing process. Purpose: Bull floats correct imperfections in the initial screeding process.
When should I start bull floating concrete?
Bull floating is performed on freshly poured concrete during the initial finishing process before surface water, called bleed water, appears. Floating with a hand or power float, is a final finishing procedure performed after the bleed water has dried.
What is the difference between bull floating and floating?
A bull float is used to smooth 95% of a slab, but it has a tendency either to pull a small amount of concrete away from the edges of the slab or to push concrete toward the edge. A hand float is used to level and smooth these areas so that they match the rest of the slab.
How many times should you float concrete?
For a really smooth finish, repeat the troweling step two or three times, letting the concrete harden a bit between each pass. At first, hold the trowel almost flat, elevating the leading edge just enough to avoid gouging the surface.
How much does a bull float cost?
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How much rebar should I use in a slab?
For a patio it is common to use a #3 bar spaced every 18″-24″ while for a driveway #4 bar is often used with a 12″-18″ spacing. Different projects require a different size rebar and will require the rebar to be spaced differently.
What is the difference between floating and troweling?
STEEL TROWELS. 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.
Why do you power float concrete?
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.
What may occur if a slab is floated too soon?
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.
What if it rains after pouring concrete?
If the rain begins 2 to 4 hours after pouring the concrete, the surface will not be damaged. Similarly, if it rains soon after the finishing stage, rainwater will not cause much damage if it does not seep into the surface. Light sprinkles of rain can cause no damage to freshly prepared concrete structures.
What is a Darby in concrete?
A darby is a long, flat tool used to smooth in plastering and rendering. It can also be used on concrete floors. It consists of two handles on a flat plate with slightly lipped edges. A darby is similar to a float, except larger. Primarily used in the final stages of wall and floor coatings, a darby is used to smooth.
How long does it take concrete to fully cure?
Concrete typically takes 24 to 48 hours to dry enough for you to walk or drive on it. However, concrete drying is a continuous and fluid event, and usually reaches its full effective strength after about 28 days.
How do you smooth out concrete after it dries?
These are the 4 steps in how to smooth concrete after it dries: Remove all imperfections on the surface. Vacuum up all debris and apply the adherent. Apply a new layer of concrete. Sand the surface and wash the concrete. Apply a layer of vitrifier to protect the concrete.
What is a concrete Fresno used for?
A Fresno trowel is used in the final stages of the finishing process to seal a smooth concrete surface prior to drying. Fresno’s can be used to cover larger areas and eliminate time consuming use of a finishing trowel.
How do you make concrete float on water?
The typical concrete mix designer for use as a building material is sand, aggregate stone and cement mixed with water. In place of gravel or sand, mix in fine glass beads. The beads are strong but much lighter than sand and stone. The glass beads are about 10% the density of water which helps the concrete float.
