Mastering Surface Preparation for Polished Concrete and Coatings

The first major step in any concrete coating or polishing project is surface preparation, but there is one step prior that will help develop a game plan. Evaluating what you will be working with will help minimize potential issues that you might encounter. 

During the evaluation process, the area's size, condition, vapor transmission level, and location need to be understood. This information will guide you in the development of a preparation plan. The plan will consist of which equipment you will bring, how to get the equipment to the area, and if using a grinder, which tooling will best fit the job.

Surface prep is dictated by the system being installed. If it is a coating system, the material manufacturer will have a surface prep recommendation printed on the technical data sheet. This could be performed using a walk-behind grinder or shot blaster. If you are polishing a slab, a walk-behind grinder is your only choice.

Surface preparation plays a key role in the success of any installation. If the surface is not properly prepared, the chance of failure dramatically goes up.  

Why Surface Preparation Is Key to Polished Concrete

The polishing of a concrete substrate results in a fully processed surface. Starting with coarse diamond tooling and gradually moving to finer diamond grits until the desired gloss is obtained. This system is using the surface prep process 100% of the time. It just happens that grinding, honing, and polishing the surface, which are considered means of surface prep, produce a very serviceable floor.

Not all diamond grit tools are manufactured the same, even from the same manufacturer. When polishing concrete, three types of tools are used: Metal bond, ceramic or copper bond, and resin bond. The reason for different bonds is to hold distinct-sized diamonds.

With the coarse grits or large diamonds, the diamonds are encapsulated in a metal alloy. The alloy is strong, having the ability to hold on to the large diamond particle. As the diamonds wear, the alloy starts to wear, exposing new, fresh diamonds. This process continues until the alloy is completely worn away, and a new set of tooling is installed.

The next step is using a ceramic bonding material or something similar. This is considered a transitional tool, as you are transitioning from a coarse metal bond to a resin bond that holds the finest polishing grits. All steps are performed using the same walk-behind grinder, only the tooling is changed.

A typical step-by-step process includes the following.

• Metal Bond
  • 30-grit
  • 70-grit
• Transitional
• 50-grit
• 100-grit
• Resin Bond
• 100-grit
• 200-grit
• 400-grit
• 800-grit  

Prepping for Coatings: A Step-by-Step Guide

When preparing the substrate for a resinous system, whether it be a thin mil system or thick trowel down mortar, two methods can be used. The same process to polish a floor can be used for a resinous system. The only difference is to stop after the first grinding step. This will clean the floor, level the bumps, and leave the surface rough enough to develop a mechanical bond for thin coatings. By changing the tooling to a bush hammer, an extremely rough profile can be obtained. A bush hammer is a tool with spikes. As the tool holder plates rotated, the spikes destroyed the surface under control. With precision, the bush hammer could provide the best surface profile for a resinous mortar or cement-based overlay.    

Shotblasting or abrasive blasting has been around since the mid-1800s. It is a highly effective method of surface preparation. The origins of shot blasting can be traced back to when it was first used in foundries to remove sand from castings. Since then, shot blasting has expanded into different industries, including construction. The process involves propelling an abrasive at high speeds onto the surface being cleaned or prepared, resulting in a clean and semi-rough finish. One of the main advantages of shot blasting is its ability to create an even texture on surfaces while also removing contaminants. All shot blasters, no matter the size, have an industrial dust collector attached during operation. It is especially important to select the proper size vac. It must be able to capture all the debris without capturing the blast media. The media needs to be recirculated back into the hopper for reuse.  

There are features to consider when selecting a shotblaster. The main ones are manual and self-propelled drive mechanisms. Typically, the smaller units will be manual. The larger machines are much heavier and much more aggressive. There are shot pattern widths to select from, and that is how the machines are named. They can range from 8” to 48” wide. The larger the blaster, the more electrical power it will need.  

Where Do You Buy Tools and Equipment for Effective Surface Preparation

Niagara Machine has been in the concrete surface preparation business for years.

Our surface preparation journey started with supplying shot blasters to clean ship decks on Lake Erie before recoating. Then, we moved on to concrete surface preparation. Not long after that, we saw a need for a grinder. Since no grinders were being manufactured in the United States, we looked to the European market for help. Once we selected a manufacturer, we started supplying concrete grinders in the United States.

Niagara’s list of grinding equipment includes planetary and rotary grinders, industrial dust collectors, and industrial diamond tooling. Since we started with shot blasters, we have expanded our inventory to every available size to fit the contractor’s needs.      

Conclusion

Proper surface preparation is crucial when installing a resinous floor system or polishing the surface to reduce failures. However, selecting the proper equipment to perform the work can be daunting. Should you use a grinder or a shot blaster? For a polished surface, a grinder is the only choice.

With a resinous system, the options are greater. A grinder and shot blaster will effectively prepare the surface, but it is always recommended to consult with the material manufacturer on the selected method.

If buying the prep equipment is not in the plan, renting is always a possibility. Sunbelt Rentals carries a fleet of surface prep equipment. They not only have the equipment but also the technicians to walk you through the operating procedures.   

Before starting, give Niagara or Sunbelt a call. By providing us with what you found during the evaluation process,  we can guide you to the most economical and efficient process. The surface preparation market is changing all the time. New equipment and tooling are being developed regularly to help installations move smoothly. It is difficult to keep up with all these changes. Allow Niagara or Sunbelt to help you with your next project that includes a level of surface preparation.