How to Trowel Concrete Smoothly

This is part of our comprehensive guide to the art of grinding and polishing concrete floors.

Trowelling concrete helps achieve a smooth, level, and durable surface. Whether you're working on a small DIY project or a large-scale construction job, understanding the correct way to smoothly trowel concrete can mean the difference between a merely passable result or a job well done. PWM can help you learn the proper way to trowel your way to a smooth finish on your concrete project. Let’s get started.

Know Your Equipment

• Darby or Bull Float: A darby or bull float is a larger tool with a flat rectangular blade that is used to initially level and smooth the surface of freshly poured concrete. It is usually attached to one or more long handles for ease of use.
• Hand Float: A float is a flat, rectangular tool with a handle, typically made of wood, aluminium, or magnesium. It is used for the initial trowelling process, helping to level the surface and push down larger aggregates. Hand floats are smaller and designed for smaller areas around edges and obstacles, or for small projects like a rubbish bin pad.
• Trowel: A concrete trowel is also a flat, rectangular tool with a handle, similar to a float but made of metal. There are both hand trowels and power trowels, which are used for larger projects.
• Edger: Edgers are used to create rounded edges along the perimeter of concrete slabs or other flat surfaces. They help to prevent chipping and create a smooth transition between the concrete and adjacent surfaces.

Time to Trowel

Before trowelling, make sure the concrete is adequately levelled. You can use a screed board or a straight 2x4 to level the concrete. Drag it across the surface of the forms in a sawing motion, moving it back and forth until the concrete is flat.

Floating

Floating is the first step in creating a smooth concrete surface.

• Wait for the concrete to set slightly. It should be firm but still moist enough to work on. You want the concrete to be moist but not too wet, as this can result in an uneven finish.
• Use a float to begin the floating process. Hold the float's handle and gently press it into the concrete. Move the float in a circular or figure-eight motion to smooth and level the surface. This will help push down any larger pieces and fills in small voids.
• Continue floating the entire surface, working from one end to the other. Be sure to overlap your strokes to avoid leaving lines or uneven spots.

Edging

Edging will create a neat and rounded edge on the concrete. Once you've completed the initial floating, edge the concrete while it's still somewhat pliable.

• Hold the edger at a slight angle and push it along the edges of the concrete to create a rounded profile. This helps prevent chipping and creates a clean transition between the concrete and adjacent surfaces.
• Pay special attention to corners and edges, ensuring that they have a smooth, uniform appearance.

Trowelling

Trowelling is the final and most critical step in achieving a smooth, polished surface.

• Wait for the concrete to set to the point where it can support your weight without leaving deep impressions but is still soft enough to trowel.
• Use a concrete trowel, which can be either a hand trowel or a power trowel for larger projects. For hand trowels, apply a small amount of concrete finishing compound to the blade to reduce friction and achieve a smoother finish.
• Begin trowelling by making overlapping passes over the concrete surface. Start at one end of the slab and work your way to the other. Trowel in a circular motion, turning the trowel blade slightly with each pass. This helps to fill in any imperfections and create a smooth, consistent surface.
• With each pass, apply gentle pressure to the trowel to compact the surface and push any air bubbles out of the concrete.
• Continue trowelling until you achieve the desired smoothness. You can usually tell it's time to stop when the concrete begins to develop a slight sheen.

Tip: For larger projects or to achieve an extremely smooth finish, you can use a power trowel. These machines make the process faster and more consistent but require experience to operate effectively.

Finishing

After trowelling, you need to mind the final finishing touches:

• Wait for the concrete to set a bit more, typically 15-30 minutes after trowelling, depending on the environmental conditions.
• For a slick finish, use a steel trowel, applying a bit of concrete finishing compound if needed. This will give the surface a glass-like, mirror finish.
• Polish the surface with the steel trowel by making overlapping passes, gradually increasing the pressure. Be sure to maintain a consistent, smooth motion to avoid creating lines or imperfections.

Tips for Achieving a Professional Finish

1. Work efficiently but don't rush. Trowelling concrete requires patience and precision. Taking your time will yield a smoother finish.
2. Check the weather. Avoid trowelling concrete in extreme heat, wind, or direct sunlight, as these factors can affect the curing process and surface appearance.
3. Consistency is key. Maintain a uniform pressure and motion throughout the trowelling process to avoid lines, ridges, or other imperfections.
4. Be mindful of the order. Follow the sequence of floating, edging and trowelling for the best results.
5. Practice on a small sample before tackling a large project. This will help you get a feel for the tools and the concrete's behaviour.
6. Keep your tools clean. Remove excess concrete buildup on your trowel or float regularly to ensure a smooth finish.
7. Use proper safety gear throughout the process. Protect your eyes, ears, lungs and hands from potential hazards.

Trowelling concrete is a skilled process that can transform a basic concrete surface into a smooth, professional finish. By following the steps outlined in this guide, using the right tools, and paying attention to details, you can achieve excellent results in your concrete projects. Remember that practice and experience will improve your trowelling technique, so don't be discouraged if your first attempts aren't perfect. With time and patience, you'll become more adept at creating beautiful, smooth concrete surfaces for a wide range of applications.

For knowledgeable and friendly advice from the experts at PWM please call 01405 862688 or email info@pwm-sales.co.uk