The Complete Guide to Polishing Concrete

Polished Concrete, when professionally done, is a perfect no-wax flooring material that gives spaces a minimalistic, professional, and sophisticated look. It is a low-maintenance, cost-effective, durable and an incredibly hard-wearing surface option that can be effectively remodelled for areas that have heavy foot traffic or that need to withstand constant movement of heavy items. With the proper floor grinding equipment, expert professionals can grind concrete surfaces, whether new or old, to a flawless, high-gloss finish. Concrete can also be coloured in many tones which largely expands its aesthetic and decorative scope.

It is eco-friendly so for businesses focusing on their carbon footprint, opting for polished concrete is a great way to be sustainable. Polishing existing concrete surfaces minimizes waste by using materials at hand instead of installing completely new flooring. The process does not require many additional products or materials thus reducing unnecessary waste.

Moreover, polished concrete has reflective properties that maximize lighting in facilities. Improved ambient lighting not only improves the space’s appearance aesthetically but also increases safety and significantly reduces energy consumption. With its versatility, sustainability and long-lasting durability that rivals floorboards and carpets, it’s not surprising that retail, commercial as well as residential spaces are incorporating this smooth, trendy and long-lasting option.

What is Polished Concrete?

Polished concrete involves mechanically polishing a concrete surface using diamond-encrusted floor grinding shoes, to the desired degree of shine and smoothness, similar to sanding wood. A common misconception is that every kind of concrete floor finish is polished concrete. When in fact, in the industry, there are multiple types of finishes. There are different methods and finishes to choose from – ranging from high-gloss minimal appearance to a speckled matte look which involves exposing a lot of aggregate in the concrete slab. The different methods and finishes include: grind and seal, mechanically polished concrete, cream-matte, semi-gloss, high-gloss finish and so on.

Grind & Seal

One of the most common finishes our clients look for is ‘grind & seal’. The grind & seal finish gives a smooth satin matte finish to the floor and is perfect for those clients that are looking for a rustic industrial finish which is popular and currently trending in cafes and restaurants. The advantage of this finish is that it’s cost-effective and helps to protect the concrete slab from stains and spillages.

Cream Finish

Cream concrete finish requires the concrete to be well cured, at no less and preferably more than 32 MPA of strength, having been laid very straight with a highly burnished finish. The difference between a cream concrete finish with a polished concrete finish is that a cream finish is achieved by not exposing any aggregate and switching from metal bonded diamonds to resin bonded earlier in the process. Being economical, the “cream” finish is perfect for industrial areas where extreme floor strength is required. It is also the obvious choice for large commercial areas subject to high traffic.

Polished Concrete

Polished concrete is more expensive than ‘grind & seal’ finish as there are a lot more steps and processes involved. Depending on the finish you are looking for, polishing concrete can involve between 12 to 18 passes with the floor grinders. The diamond discs need to be changed while increasing the grit of the diamonds for each pass. In between the passes, a chemical hardener must be applied and allowed time to seep and densify into the slab. This is an intricate and time-sensitive process and the main reason why polished concrete is much more expensive.

HOW TO POLISH CONCRETE?

As with any other specialized technique, polishing is a multi-step process requiring use of the proper tools and equipment to achieve high-quality results. Polishing concrete is quite similar to sanding wood. The process is usually carried out by large floor grinding machines that have diamond-encrusted cup wheels installed on a spinning disc. These diamonds (akin to sandpaper) are used to grind down concrete surfaces to the desired degree of shine and smoothness. Similar to sanding wood, you gradually progress from coarser grit to finer grit (in this case, grit is the particle size of the diamond) abrasives to eventually achieve a glossy, mirror-like finish.

Concrete can be polished using wet or dry methods. Although each has its advantages, dry polishing is the method most commonly used in the industry today because it’s faster, more convenient, and environmentally friendly. Wet polishing uses water to cool the diamond abrasives and eliminate grinding dust. Because the water reduces friction and acts as a lubricant, it increases the life of the polishing abrasives. The key disadvantage of this method is the clean-up. Wet polishing creates a tremendous amount of effluent that crews must collect and dispose of in an environmentally sound manner. With dry polishing, no water is required. Instead, the floor polisher is attached to a dust-containment system that vacuums up virtually all the mess.

Types of Diamonds

There are many different types of Diamond Cup Wheels, which will have various effects. Generally, Cup Wheels are measured in grits. The higher the grit ratio the finer finish it will leave on the concrete. For a more polished effect, a Cup Wheel with a high grit ratio would be used. The types of diamonds used are as follows:

• Resin Bond Diamonds, are diamonds fixed in resin compound. These are used for medium to fine grinding applications from a 50 – 3500 grit finish. Resin bond diamonds are the professional diamonds for Concrete Floor Polishing, and run through the grits from 50 grit, step by step through to 3000. The wear rates of Resin bond diamond pads vary from project to project. Most floors are ground with a Metal Bond Diamond (Grit up to 60/80 or 80/100) prior to starting on the Resin bond polishing process.
• Hybrid Diamond Polishing Pads, is a mixture of a metal and a resin bond diamond. These are used as a transition tool after metal bond diamonds, to quickly remove scratches from the floor. The Hybrid pads are proven to give high grinding performance and can be used in wet or dry applications.
• PCD Diamonds aka Polycrystalline diamonds, are designed for a high speed, fast, aggressive removal of glues, paints, coatings or epoxies – thicker than around 3mm.

A step by step guide to how we polish concrete at Perfect Concrete Care:

1. We start with one pass with 20grit aggressive diamond shoes. This gets rid of any imperfections in the slab and helps to even it out.
2. We would then use a quick setting filler to fix all the tiny holes, cracks and imperfections in the slab.
3. Next, we would use 40 grit diamond shoes to smooth out the slab further.
4. Then we apply the concrete densifier and wait about 20 mins for it to seep into the slab.
5. After which we use 80 resin pads to make the slab even smoother.
6. Afterward, we apply yet another coat of concrete hardener and wait for that to dry.
7. Then we use 120 grit resin pads to smoothen the slab further.
8. Apply another layer of concrete hardener.
9. Later, we use 240 resin pad shoes and give them another pass.
10. Apply another coat of hardener.
11. After that, we switch to 400 grit resin pads and give it another pass.
12. Apply another layer of hardener.
13. Then we use 800 resin pads and perform another pass.
14. Apply another layer of hardener.
15. Next, we use 1500 grit resin pads and give it another pass.
16. Finally, we use the final 3000 resin pads to give it its final polished finish.

APPLYING CONCRETE SEALER

A concrete sealer is essential for protecting surfaces from water damage caused by freeze/thaw cycles, stains from dirt, dicing salts, oil and other contaminants, and much more. There are two main types of concrete sealers: film-forming sealers and penetrating sealers.

Film-forming sealers include acrylics, epoxies, and urethanes that form a coating on the surface of the concrete. Film-forming sealers, especially acrylics, are more susceptible to wear and will need to be reapplied frequently. This type of sealer is sometimes referred to as a topical concrete sealer or a coating. You should opt for a film-forming sealer if you want a wet look or high gloss finish that enhances the colour of your concrete.

Penetrating sealers include silanes, siloxanes, silicates and siliconates that penetrate the concrete to form a chemical barrier. Penetrating sealers have a longer lifespan and are a great choice for exterior applications. They don’t peel, delaminate or wear away. This type of sealer is sometimes referred to as an impregnating concrete sealer. You should opt for a penetrating sealer if you prefer a natural finish that will not change the look of your concrete.

WHY CHOOSE PERFECT CONCRETE CARE?

A commercial concrete polishing service can be the first step in improving the look, durability and safety of your concrete floor. Polished concrete is an art that can only be perfected with professional expertise. That’s why you need to make sure you engage the best concrete polishing contractors in Sydney. Our professional operators have years of experience in the concrete grinding and polished concrete industry. With years of experience in the industry, we have the knowledge, skill, experience, and expertise to achieve the perfect polished concrete finish you desire. Furthermore, we only use the best quality machinery, equipment and materials available in the market to ensure our valued clients get the best results possible.