Every time a coating or resurfacing type material is applied to a concrete substrate, the manufacturer of such material will recommend the surface preparation best suited for that material. Some manufacturers will recommend tools or equipment needed to prepare the surface; others will describe the required surface roughness. No matter how they describe what will be needed, some level of mechanical surface prep will be required.
Understanding Concrete Surface Preparation
The process of preparing a concrete substrate to accept a coating or resurfacer entails mechanically abrading the top surface layer of a concrete slab prior to the application of the material. Materials bond in two ways, absorption into the surface and mechanically locking onto the surface. If the surface is weak, contaminated, or nonabsorptive, the bond might be compromised.
Surface preparation is much more than just cleaning the surface. Granted, there are materials that only require the surface to be cleaned, but that is not the norm. Most will require the surface to be abraded.
Concrete Surface Profile (CSP)
In the late 1980’s a group of Engineers, Contractors and Material Manufacturers came together to discuss a widespread problem in the concrete repair industry: surface preparation. Material manufactures were developing repair materials new to the industry. Engineers were specifying materials for their repair projects. The contractors were expected to install these materials correctly. The big issue was how the surface of these repairs needed to be prepared for the materials being used on a consistent basis.
Out of that meeting, the International Concrete Repair Institute (ICRI) was born. Now that ICRI had a structure in place, they could fulfill the first mission which was to develop a standard that can be used by all parties when specifying, developing, and installing coatings and repair material that everyone can understand and follow.
Concrete Surface Profile (CSP) is a method of visually showing how rough the surface needs to be for a specific material. It is a description of the surface profile required that is currently used worldwide by material manufacturers. Each surface profile level is associated with one or more mechanical means to perform the work. There are ten levels, 1 being the least aggressive and 10 being extremely aggressive. At that point, CSP was adopted by most material manufacturers which lead to common terminology between all parties involved.
Methods and Techniques:
There are 3 mechanical methods used to prepare a horizontal concrete surface. Shotblast, grind, and scarify. Within these methods there could be multiple CSP levels that each can provide. For example, when using a shotblaster the size of shot, the speed the machine travels, and the size (power) of the machine all have an impact on the CSP level it will produce.
|Grinder 70 grit metal bond tool
|Grinder 14-30 grit metal bond tool
Bush Hammer tool followed by 30-grit metal bond tools
Shotblaster 110v/220v/460v 330 steel shot
|Grinder Bush Hammer tool followed
by 16-grit metal bond tools
Shotblaster 110v/220v/460v 390 steel shot
Scarifier Fine Drum
Grinder Bush Hammer tool followed by 6-grit metal bond tools
Shotblaster 220v/460v 390 steel shot
Scarifier Medium Drum
Shotblaster 220v/460v 390 steel shot
Scarifier Medium Drum
|Scarifier Coarse Drum
Types of Concrete Surface Preparation Tools
Not one preparation method will produce every CSP level. Looking at the chart above, you can see to obtain every CSP level, multiple pieces of equipment will be needed.
- Shot Blaster
- Shot blasting concrete works by using a machine that holds a centrifugal wheel that propels metal shot blast media at a high velocity in a controlled pattern and direction. The blast wheel throws shot at the concrete surface at a controlled rate removing contamination while roughening the substrate. The light material removed is extracted from the surface with an industrial dust extractor. The steel shot bounces up off the floor and is captured in a recovery chamber for reuse. The aggressiveness is adjusted by the size of steel shot used and the travel speed of the machine.
- Concrete floor grinders come in distinctive styles, rotary and planetary. They both use diamond abrasive tooling to do the cutting or grinding work. Both will perform the work; it comes down to personal preference or availability which one is chosen.
- The tooling chosen will produce a certain CSP level. A 30-grit metal bond tool will produce a CSP 2. If a Bush Hammer on a grinder is used, a CSP 5 can be obtained. Select the tool to match the CSP needed.
- A concrete scarifier is a machine that uses spinning blades, attached to a rotating drum, to chip away at the top layer of a concrete surface. These machines are great for removing coatings and creating a level space, free of bumps and dips.
- It can obtain a CSP 4-10 depending on the drum used.
Maintenance and Safety Tips
No matter which prep method is selected, job site safety is crucial. All equipment described above has moving parts driven by a motor or engine. Wearing the correct Personal Protection Equipment (PPE) can minimize serious and minor injuries while in operation. Always follow the manufacturers safety precautions printed in the operating manual.
All equipment requires a level of maintenance. By following the maintenance section in the printed equipment manual will ensure a long service life.
Selecting the surface preparation equipment to fit the project is much more than going into your shop and grabbing the first piece of equipment you see or renting one from someone that doesn’t know the first thing on how to operate it. Knowing the hardness of the substrate, which CSP the material manufacturer is requiring, the access into the area, what electrical power is available, and if propane or gasoline can be used all come into play. If you will be renting, working with your local Sunbelt Rentals will provide you with what you need. If buying, the local Niagara Machine field representative has extensive surface preparation knowledge to get you into the correct machine. Don’t hesitate to reach out to them!