The FMP Blog

Everything to Know About Concrete Finishing

  • May 16, 2024

When it comes to concrete, the finishing you choose matters. Concrete finishing helps reinforce durability and aids in the aesthetics and functionality of the slab. Thus, it’s critical that you select the appropriate finish for the job. 

Far from etching your initials in fresh concrete and calling it good, concrete finishing involves various processes where the tools and methods used vary, depending on the job.

This comprehensive overview contains everything you need to know to get concrete finishing right the first time. 

Table of Contents

1. What is Concrete Finishing?
2. What Are the Different Concrete Finishing Techniques, And What Tools Are Required for Each?
3. Concrete Finishing Processes
4. After Finishing


What is Concrete Finishing?

Concrete finishing is the process of addressing the concrete surface — either by smoothing it or creating a textured decorative finish — after it has been consolidated and leveled, but before it fully cures.

Choosing the appropriate concrete finish for the job helps mitigate things like slips; smooth concrete on a pool deck is never a good idea! It also maximizes ease of use; a finely polished concrete finish on countertops makes wiping away crumbs and spills simple.

Concrete finishing can also be aesthetic and decorative in nature, achieved by stamping a stenciled design on walkways or patios, or dying it so it blends better with the landscape.


What Are the Different Concrete Finishing Techniques, And What Tools Are Required for Each?

First and foremost, the type of finish used for a particular project depends on the purpose: what will the concrete be used for?

If it’s a walkway area that will experience heavy foot traffic, slips and trips are a real concern. Thus, choosing a finish that offers some traction, plus a flat, even walking surface, is ideal. 

Aesthetics should also come into play, especially if the concrete surface is part of a common area such as a courtyard or a walkway that winds through a garden.

Driveways, concrete patios, or concrete slabs that are strictly utilitarian can have a more straightforward finish, as aesthetics may not be much of a concern. The type of finishing tools needed depends on which technique is being used.

The main types of concrete finishing are:

Broom Finishing 

broom concrete finishing

This is a popular finishing technique for walkways and patios. The stiff bristles from the broom (similar to a push-broom) create a textured surface of fine, straight, continuous lines, or can be fanned out in an arc-like design.

Tools include: 

  • Stiff-bristled broom
  • Edging tools

Exposed Aggregate Finishing 

Exposure aggregate is commonly found on pathways, shopping centers, and around swimming pools due to its textured surface and visual appeal.

For this style of finish, the technique involves spraying the surface of the concrete to expose the layer of stone or “aggregate” below and then scrubbing it with a brush. Timing is everything, especially for this finish.

Tools include:

  • Surface retarder
  • High-powered pressure washer
  • Stiff-bristled brushes

Hand or Power Troweling 

Extremely durable and resilient against chemical agents, heavy foot traffic, and water damage, a trowel finish is used for indoor spaces such as supermarket floors, warehouses, and modern interiors. Hand or power troweling creates a smooth, even finish across the surface of the concrete.

Tools include:

  • Steel and margin hand trowels
  • Power trowels

Stamped Concrete 

This method provides a cost-effective means of mimicking pricier materials such as slate or other natural stone. The concrete forms or stamps themselves can be purchased to mimic brick, cobblestone, or a variety of other natural patterns.

When this strategy is used in conjunction with a stain or color, only the most discerning eye can tell the difference between the concrete version and the real thing.

After the concrete is poured and leveled with a screed board, the stamping process begins. Because of the short window of time in which this finish can be used, it’s a good idea to prepare the stamping layout beforehand and have enough help ready to complete the job within the allotted timeframe.

Tools include:

  • Stamping mats or texturizing forms
  • Trowels and edging hand tools
  • Release agents

Colored Concrete 

Purely aesthetic, colored concrete can be combined with another concrete finish. Whether the desire is to mimic stone or another type of material (or to just provide something fresh and different), concrete can be stained or dyed after it’s been laid. Or, the color can be added before pouring, along with the other concrete mixes.

Tools include:

  • Integral color pigments or color hardener
  • Whichever tools are necessary for the desired finish

Polished Concrete 

Another popular surface for high-traffic areas such as airports, commercial kitchens, retail spaces and more, a polished concrete floor finish adds a glossy look to the surface. It’s also popular with concrete countertops.

The process involves grinding the surface with progressively smaller discs to create a smooth texture and then applying a concrete sealer or epoxy for a glossy look.

Tools include:

  • Concrete grinders
  • Polishing pads
  • Diamond abrasives
  • Brushes, rollers, or a sprayer for sealing

Concrete Finishing Processes

No matter the desired finish, the first step after the concrete has been laid and leveled, any corners rounded with an edger, and the proper control joints added, is to prepare the surface.

Before getting into how to finish concrete, there are a few things to note beforehand:

  • If a smooth finish is desired, a trowel can be used after the concrete is partially hardened. The same applies for the broom finishing technique.
  • If the job involves concrete stamping or stenciling, the concrete should feel mostly dry to the touch. Test it out by running your fingers along the surface—you don’t want any sand to stick to them.
  • Remove any excess concrete, debris such as leaves, or other loose materials, and check to ensure any holes, voids, or imperfections are smoothed over and patched.
  • Be mindful of the weather. If the job is outdoors, note the predicted temperatures. The hotter the temperatures, the quicker the concrete dries.

Broom Concrete Finishing Process

The ideal time to start the broom finishing process is after the bleed water has dried. Depending on the temperature, this can take anywhere from 20 minutes to four hours after the concrete has been floated.

Some contractors (Learn more: What Does a Commercial Contractor Do?) like to trowel the surface before applying the broom finish. The benefits of troweling help reduce potentially unsightly imperfections, such as working any bull float lines out. Just be careful not to overwork the surface.

During the broom finishing process, the broom is typically moved from one side to the other without stopping. Pull the broom towards you. When you reach the end, set it for the next row and follow that same process. Brooms come in a variety of widths, and the bristles can be made from many different types of material. 

For larger jobs, there are handleless brooms that can be pulled across the surface of the concrete with ropes.

Exposed Aggregate Concrete Finishing Process

This method can be achieved in two ways.

The first is to spray the concrete with water as it hardens and brush it away to reveal the layer of aggregate below. This option is best suited for smaller jobs, as timing is everything. It can be challenging for those attempting it for the first time because if too much concrete is washed away, the stones can easily break loose and the whole thing may begin to crumble.

The second choice is to spray the surface with a retarding agent, cover it with polyethylene sheeting, and leave it overnight. The following day, the surface is washed away with a high-powered stream of water and through brushing.

Hand or Power Troweling Concrete Finishing Process

After the concrete is partially hardened, a steel trowel can be swiped across the surface with applied pressure in large, sweeping, overlapping arcs.

For bigger jobs, power trowels are the way to go.

These can be rented and resemble lawnmowers in some ways. Depending on the size of the job, they come in both push and riding varieties. 

Most have a float pan and finishing blade that work to leave the surface smooth.

If you’re using the hand-powered option, the trick is to walk pulling the power trowel behind you. This reduces the likelihood of leaving footprints. Repeat row by row until the job is complete.

Stamped Concrete Finishing Process

Once the concrete has been poured and bull floated, apply a release agent when the concrete is ready to stamp. You’ll know it’s ready by poking it.

If you can leave a quarter-inch fingermark without any sand sticking to your fingers, it’s time.  

The release agent acts as a barrier between the concrete and the stamps. Once it’s been applied, the process can begin. After finishing, wash off the excess release agent with water and a scrub brush. When the concrete is dried, apply a sealant with a sprayer or roller.

Colored Concrete Finishing Process

There are a few different methods used to color concrete. The first is integral coloring, where a powder, liquid, or granular tone is added during mixing. Staining, color hardeners, dyes, and even paint are other means of adding color.

Color can be used to blend and match the concrete better with natural surroundings. Reddish or earthy tones go better in backyard spaces, and concrete can also be colored to mimic stone or brick.  

Colored concrete can be used in conjunction with any other fishing process, such as to make a stamped surface appear to be made of stone.

Polished Concrete Finishing Process

This happens after the concrete has fully cured, which can take three to four weeks. It’s achieved by grinding and smoothing the concrete with a grinder and concrete polisher machine, utilizing progressively finer pads with each pass. 

After that, a chemical hardener is applied to help densify the concrete. Finally, the concrete gets polished.

To start, grind with 30 or 40-grit metal-bonded diamond pads. Next, grind with an 80-grit. Lastly, use a 150-grit or finer if desired.

After grinding, apply the chemical hardener. Once that hardens and dries, the polishing can begin. Start by polishing with a 400-grit resin-bond diamond polisher, then an 800 before finishing with a 1500 or 3000-grit resin bond diamond polisher, depending on the desired level of sheen.

Finally, apply a guard stain to protect and make the surface easier to maintain.


After Finishing

For all the finishes that occur during the setting period, it’s important the concrete gets properly cured. One way to do so is to keep it moist, spraying the wet concrete with a hose and not letting it dry for the first week.

This makes it almost 50% stronger than concrete that’s simply left to set and dry on its own.

Another finishing technique involves sealing the concrete with a chemical sealant. This can help make the surface easier to clean and maintain.

It can take up to 28 days for the concrete to fully cure. However, concrete can handle light foot traffic after three or four days, and cars can be driven and parked on it after five to seven days.


Conclusion

Whether this is part of an ambitious DIY project or you have some experience working with concrete, remember to take it slow and pay attention to the conditions around you. When it comes to concrete, each step is important: don’t start until you know how you will finish.

To put it in the hands of the professionals, contact FMP Construction today!

Latest Posts

© 2023 FMP Construction. All rights reserved.