Polishing Concrete like a Pro Even on a Budget

how to polish concrete

Polished concrete floors are common nowadays in residential properties.This is unlike before when such floors could only be found in public spaces such as lobbies of office buildings and malls.

One reason for its popularity is because it lasts longer than other types of flooring. While a tiled floor may last 10 to 20 years, a polished concrete floor will serve for more than 100 years.

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Plus, they are easy to maintain and are more beautiful. Their durability also means you save money in the long run.

And another way to save money is to polish your concrete floor by yourself. If this is anything you’d consider doing then read on – here’s all the information you need to let you polish like a pro.

Just as any other specialized skill like concrete cutting, core drilling and wire sawing, concrete polishing is a multi-step process that requires the use of the proper tools and equipment to get better results.

To help you get started, here’s an overview of concrete polishing basics.

Knowing The Basics

Concrete polishing can be likened to wood sanding. You need polishing machines fitted with diamond abrasives just like sandpaper.

The rough surface with diamond abrasives is what polishes the concrete surface, bringing out its desired level of smoothness and degree of shine.

Just like in wood sanding, work the surface gradually. Start with an abrasive with a coarser grit and proceed to one with a finer grit to achieve a glossy finish.

Grit refers to the diamond particles on the coarse surface of the tool.

Note that concrete diamond abrasives come in different grits. Use a low-grit abrasive and progress to a high-grit abrasive for a lustrous, mirror-like finish.

A low-grit abrasive is typically a coarser and more aggressive tool.

A higher-grit diamond abrasive such as a 3000 grit tool on the other hand is more even and produces a high shine and glossy look.

RELATED: Key Steps in Concrete Grinding and Polishing

Concrete Polishing Methods

There are two primary methods of polishing concrete: wet and dry polishing methods.

  1. 1. Wet polishing method

This method uses water to cool the diamond abrasives. The water acts as a lubricant and reduces friction between the diamond abrasives and the concrete surface you are polishing.

There is no dust produced in this method and with the lubrication, the polishing plates are likely to have a longer service life.

The diamond segment is often bonded to the grinding disc using a resin that can melt at high temperatures. The water therefore keeps them from melting by controlling their temperatures and increasing their lifespan.

Wet polishing ensures no silica dust (potentially harmful to health) goes into the air.

But this method produces mud from the mixture of the ground concrete dust and the water.

You have to clean up the mud and dispose it in an environmentally sound manner. Wet polishing can therefore be a slower option and may also be messy for interior spaces in homes and retail setups.

  1. 2. Dry polishing method

No water is used in this method. The plates are designed to withstand the high temperatures generated while polishing concrete. Though the technology also allows the disc to withstand the friction, it reduces its lifespan nonetheless.

Dry polishing machine has a vacuum system for dust containment.

This is therefore a more convenient polishing method and increases productivity by reducing downtime for commercial purposes. It’s also convenient for concrete polishing in interior spaces.

The vacuum system however won’t capture 100 percent of the dust produced. Some of the harmful silica dust may remain on the floor and may get into the air as people walk on it.

Now that you know about the wet and dry polishing, you can decide which suits you. Regardless of the method, here’s the procedure to  get the job done.

– Determine the condition of the concrete

Use a MOHS concrete hardness tester.to evaluate the concrete’s surface before you polish.

– Prepare the surface

Before polishing, the concrete’s surface must be clean. Mop it and removing coatings and sealers if any. If it has thick coatings, consider using a 16 or 20 grit diamond abrasive.

As a rule of thumb, the more aggressive the tool, the better and more suitable it is for coating removal.

After removing the coatings, repair the surface by sealing any crack and joint. Use an epoxy or other semi-rigid filler.

But in case the floor has only very light coating or minor blemishes, this phase won’t as necessary or elaborate. You can simply proceed with the initial process of floor grinding.

– Start polishing

For this initial polishing, use of a low-grit abrasive. Start with a 30 or 40 grit metal-bonded diamond.

Then, proceed to grind with an 80 grit metal-bonded diamond abrasive. This will be your initial rough grinding, which prepares the concrete for its final smoothing.

As noted earlier, concrete grinding is a multi-step procedure.  It usually has three or four steps, depending on the condition of the concrete.

– Densify the concrete

It’s helpful to apply a liquid chemical hardener to the concrete after the initial grinding. This will help densify and solidify the surface for a better polish and extra protection from staining and penetration of water.

– Final polish

Use a 100 or 200 grit resin-bond diamond to polish, then progress to polish with a 400 grit resin-bond diamond and finally with an 800 grit resin-bond diamond. Like grinding, polishing is a multi-step process, depending on the condition of the concrete.

You may finish with a 1500- or 3000-grit resin-bond diamond. This will result in a lustrous finish, depending on your desired level of sheen.

– Protect the polished surface

This is optional. You may apply a stain guard to help shield the polished surface. This makes it easier to maintain.

Conclusion

Each concrete polishing job presents a different set of conditions and challenges. Don’t be discouraged. Instead,  deal with it with the end result in mind so you’ll have the desired finish.

How to Choose the Correct Type of Concrete Cutting Blades

concrete cutting blade

The right concrete cutting blade can spell the difference between a cost-effective and efficient job and one with lots of downtime and additional costs.

Thus, you must know what to look for in a blade for your next concrete cutting project.

There are various considerations to make as you seek to get your best blade. But first, get to know the types of diamond blades available in the market.

Here are the options to choose from:

Dry-cutting blades

These are used to cut dry, hard concrete.

Sintered diamond blades are routinely used for dry cutting. They are typically high density alloys of silver and diamond – made by sintering steel cores, diamonds and metal bond materials already put into molds.  

These diamond blades are in two types:

  • Hot-pressed diamond blades

Well alloyed, with high density segments. They have a longer service life.

Marble and Granite Cutting Saw Blades
Image Credit tomade-in-china.com

 

  • Cold-pressed diamond blades

have low-density diamond segments with high porosity. This feature can improve the cooling condition when the blades are in use. They however have a shorter service life.

Diamond Saw Cutting Blade | MegaSaw
Image Credit to made-in-china.com

Sintered diamond blades can cut marble, granite, concrete, asphalt, ceramics and other dry building materials.

Note: Some sintered diamond blades such as the continuous rim diamond blades can only be used in wet cutting.  

 

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Wet-cutting blades

Water must be used to cool the blades, in contrast to dry-cutting blades that need no cooling. These are used to cut green concrete.

Silver brazed diamond saw blades are typically used in wet concrete cutting. The diamond segment of a silver brazed diamond blade does not have a transition layer.

They are brazed directly to the steel cores using silver-based brazing films which normally contain 40 – 50 percent silver.

As such, silver brazed diamond blades cannot be used in dry cutting. This is because the high temperatures generated in the dry cutting can melt the silver solder, causing the diamond segments to fall off the blade.

 

Laser welded diamond blades

These can be used in both wet and dry cutting. They are made by fusing the diamond segments and steel core by laser welding.

Cutting Saw Blades | Megasaw
Image Credit to Diamond King Tools

The diamond segment-steel core junction is melted to form a connection that can withstand high temperatures produced in dry cutting.

It’s still however recommended that laser welded diamond blades be used with lots of water, (wet-cutting) because dry cutting can cause the diamond segment or steel core to wear off and break.

 

Things to consider when choosing concrete cutting blades

The blade components

Armed with an understanding of how a diamond blade works, it becomes easy to pick a blade with the right cutting quality and characteristics that suit your needs. Here are the basic blade components and what to look for in each component:

Cutting Concrete | Megasaw

 

  • The diamond crystals

Are the sharp cutting teeth that slice through concrete as the blade rotates. The diamonds at the surface become dull with time as you use them. The matrix gradually sheds away worn out diamond crystals to expose new, sharp diamonds embedded within it.

 

  • The matrix

The metal bond that holds the sharp diamond crystals in place until they wear off. The harder the matrix the longer it takes for the blade to wear away.

 

  • The metal core

A steel disc that was precision engineered with a segmented rim. This holds the diamonds.

 

  • The weld

Attaches the diamond cutting segments to the core. Can be laser or solder weld.

For soft, abrasive materials like green concrete, use a blade with a hard metal bond so the diamonds exposed at the surface are fully utilised before they get shed off.

For hard, solid and non-abrasive concrete, use a blade with soft bonds to allow the matrix to get rid of worn out diamond particles and ensure that sharp new diamonds get exposed with ease.

 

Characteristics of the concrete

The choice of blade depends on  material you want to cut. Consider characteristics such as:

  • The hardness of the aggregate
  • The type of sand
  • The compressive strength

Concrete with a compressive strength below 3,000 psi is considered soft. On the other hand, concrete with a strength of 6,000 psi and above is hard.

Saw Cutting Concrete | Megasaw

Be sure to use a blade with a hard bond to cut soft concrete. When cutting  concrete with high psi (hard) however, use a blade with a soft bond.

This is because high-psi compressive strength, hard aggregate and hard sand tend to dull the diamond particles quickly.  Thus, a softer bond will allow new diamonds on the blade to be exposed as quickly as needed for better work.

 

Timing of the cut

Green (freshly applied) concrete is softer. Use a blade with strong bonds on the matrix so you can maximise the use of the exposed diamond particles before they are eroded.

Newly Set Concrete Cutting | MegaSaw

This would apply if you cut the concrete approximately 1 to 2 hours after finishing.

Beyond that time, the concrete would already be hard. You’d want to use a soft-bonded diamond blade to cut it.

 

Cost of the blade

Like any product, manufacturers offer diamond blades at various prices depending on the quality. Options range from basic economy to professional or top-of-the-range versions.

They differ primarily on the diamond content, the most important part of the blade. The higher the diamond concentration the better the quality and the higher the amount you’ll typically pay.

In considering the cost, look at what’s important to you. Is it the initial savings from buying an inexpensive blade or the value given by a more expensive blade in the long run?

For small cutting jobs that involve little run on the blade, you’ll likely save money by buying the economy blade. Jobs that involve frequent or long hours of use however make top-quality blade more cost effective in the long run.

 

Conclusion

If the quality-cost consideration of buying your own blade shows you would be paying more that you are willing to, it will be better to hire a professional concrete cutting contractor like MegaSaw. By this, you avoid the hassle and unexpected additional costs.