How to Trowel Concrete Like a Pro

How to Trowel Concrete Like a Pro

Getting that refined, smooth finish to your concrete and masonry takes time and effort. And there’s only one way to give concrete a smooth, finished look: by troweling.

Though it’s hard work, troweling is necessary for concrete and masonry finishing and is the best way to finish small to medium-sized slabs.

 

What is Concrete Troweling?

Troweling smooths and evens surfaces on freshly placed concrete. It’s done immediately after floating, and before the concrete dries. Troweling also hardens the concrete, fine levels the surface, and increases its density.

Troweling can be done by hand or with a power tool, but hand troweling offers more precision, especially for small projects. A hand trowel is typically composed of a flat steel blade with an attached handle. It’s pushed and pulled across a slab’s surface. Selecting the right trowel depends on the type of work being performed as well as your hand measurements.

 

When and How Should I Begin Troweling?

In the concrete finishing process, troweling is done after floating, and after the bleed water has evaporated. Floating diminishes the number of high spots and reestablishes moisture in the surface mortar that was lost due to evaporation. It also fills holes in the concrete. Floating should always be done before you finish with a trowel.

It’s important to use the right trowel for your project. Choosing a trowel is largely based on the size of the concrete slab that you’re working with. There are many types of trowels available, from stainless steel to high-carbon steel and blue steel.

Hand trowels are usually sized 3 to 5 inches wide and 10 to 20 inches long. They look very similar to hand floats; however, trowel blades are much thinner and are made from different types of steel. Stainless steel is highly recommended since it won’t rust or create any stains on the surface of your concrete.

 

Why is Troweling Important?

The steps you take after concrete placement are important to ensure the concrete is properly finished. Surface defects can take away the beauty of concrete, even in the best designs, if the concrete isn’t placed and finished correctly. Trowels compress the top layer of the slab, and a successful troweling job adds strength and a durable finish.

When it comes to troweling, timing is extremely important.
There are two mistakes to avoid: 1) Troweling too early, and 2) Troweling too much.
Both mistakes can result in tiny cracks in the surface, as well as a weakened and dusty surface.

If you steel trowel too early, you could damage the surface of the concrete by trapping moisture or air underneath. Troweling too early can also result in eventual scaling and blisters due to trapped rising bleed water and air. Early scaling results in a weak layer of concrete that may break when exposed to winter conditions and deicing chemicals. Using a steel trowel too early could also cause the top layer to delaminate. Let the concrete set properly and don’t be in a rush to trowel.

Troweling the concrete surface excessively may result in a near-surface zone of weakened concrete and can destroy the air-entrainment along the surface of the slab. Additionally, overworking the concrete can create excessive mortar at the top surface.

 

How Should You Trowel?

Use a large-sized trowel to spread the blade pressure over a large area of concrete, as this minimizes the risk of sealing the surface too soon. As the surface becomes harder, perform more troweling with smaller trowels.

If your job is larger, use a fresno trowel, which is a trowel attached to bull float handles. When you use a fresno trowel, it eliminates the need to walk out onto the slab. However, fresno trowels don’t require as much pressure as a regular trowel, which ultimately may result in concrete that’s less wear-resistant and dense.

Perform the first troweling using a wide broken-in trowel – one that is at least 4 ½ inches wide so you can work the trowel flat, avoid digging into the surface, and minimize the risk of prematurely sealing the surface. Keeping the blade as flat as possible, move the trowel in a sweeping arc motion.

Additional passes may be necessary to improve surface smoothness. With each pass, increase the tilt angle of the trowel blade to increase blade pressure, which creates a smoother, harder surface.