There are many satisfactory methods of preparing a substrate to receive a flooring system. The preparation method is typically chosen based on service requirements, time allowed for entire process and accessibility.
Personal Protection Equipment
It is the responsibility of the surface preparation contractor and the flooring contractor to insure that all personnel are properly protected from hazards. We are committed to promoting awareness regarding these potential hazards. All of our products are rated according to the Hazardous Material Identification System (HMIS). OSHA regulations specify when, where and how workers are to be protected. These regulations and the local OSHA officials should be consulted as necessary to insure proper protection, compliance with the law, and to avoid liability issues. Safety and health issues should be addressed prior to the start the job.
Testing For An Existing Sealer
Test to see if the floor is “sealed” by pouring a small amount of muriatic acid on the floor in several spots. If it “froths” (a mass of small bubbles in liquid caused by agitation, fermentation, etc.; foam) instantly, the floor is not sealed. If the acid doesn’t froth immediately, a sealer and/or paint is present and must be removed by scarifying, steel shot blasting or other mechanical methods.
Salt Contamination Testing
Salt contaminated slabs that contain steel reinforcement are very susceptible to corrosion of the reinforcing steel. As the steel corrodes it expands causing cracking, delamination of concrete and any toppings bonded to it and eventually, structural failure of the slab. Obvious signs of chloride or salt contamination are spalled concrete with exposed, rusted reinforcing steel. Testing is recommended to determine the depth of contamination and the extent of corrosion activity. A Litmus Test for pH will determine the presence of chloride or acid contamination, if the pH is below 10.
Reasons For Surface Preparation
Surface preparation of a concrete substrate is required to remove surface laitance to create a surface profile and porosity for adhesion of polymer floor systems.
Methods of Surface Preparation
Care should be taken to define the degree of abrasion required for the coating system so that the concrete will not be eroded beyond what is necessary. All concrete surfaces should be abraded to remove laitance and contaminants. The following Table describes the required profiles according to the ICRI guidelines for various coating systems.
Shot-blasting is the recommended method of surface preparation of concrete for most polymer floor installations. Shot-blast equipment utilizes an alloy wheel spinning at high speeds to throw small steel particles at the substrate in a controlled, dry, 99% dust-free operation. This process removes surface contamination, adds profile and vacuums the concrete clean in one process. The size and angularity of shot, along with the travel speed of the unit, can be adjusted to determine the degree of the surface profile. Because shot-blasting is a dry preparation process, it allows the installation to begin immediately after completion of prep (surface must be dry before blasting). Shot-blasting will also identify weak areas in the surface of the concrete.
2. Diamond Grinding
Diamond grinding should only be used in areas inaccessible to shot-blasting and then only with coarse diamond wheel.
Scarifying is primarily used for the removal of deteriorated concrete, coatings and polymer flooring systems.
4. Hand Tool
Hand tool preparation consists of the use of mechanical tools and equipment designed to abrade or chip away the surface of the concrete. Common tools available include chipping hammers, hand held diamond grinders and concrete crack chasing saws. These tools are typically used to make keyways, prepare edges against walls and columns.
Removal and Repair
ASTM D 4258-83 Standard practice for surface cleaning concrete for coating. This practice includes surface cleaning of concrete to remove grease, dirt, and loose material prior to the application of coatings. Procedures include vacuum cleaning, air blast cleaning, water cleaning, detergent water cleaning, and steam cleaning.
Removal of bond inhibiting contaminants
This includes, but is not limited to removal of oils, grease, wax, sealers, curing compounds, laitance, salts and any other hydrocarbon based materials. This will ensure that a good bond takes place between the resinous flooring and the concrete substrate.
Removal of Adhesives, Mastics and Membranes
In many retrofit projects, existing tile, VCT or sheet goods are being replaced with polymer flooring systems. Removal of the floor finish will often leave a layer of some type of mastic, adhesive or membrane. In thin applications these materials can often be totally cleaned up by shot-blasting the concrete. In thicker applications, the steel shot will tend to bounce, requiring additional preparation with the use of scarifying equipment or possibly even the use of chemical strippers.
Removal of Existing Seamless Floor
Like mastics and adhesives, the need to remove an existing seamless floor will occasionally arise. There has been much progress made in the development of equipment for removal of resurfacers. Typically, removal requires a heavy grinder with “rotating heads”. These heads can be outfitted with different “teeth” or carbide “blades” for removal of a particular type of overlay.
Types of Substrates
Regular concrete surface must be prepared with a steel shot-blast machine, scarifier or diamond grinder. Floors with oil, grime and grease should first be cleaned with a Cleaner/Degreaser before preparing. Allow floor to dry. Good ventilation, fans and/or auxiliary heat will accelerate drying time. Do not use oil fired portable heaters.
Replacement of Structurally Deteriorated Concrete
Replacement of structurally deteriorated concrete must be done in accordance with The International Concrete Repair Institute (ICRI) Bulletin. Make sure of minimum cure time before installation of resinous flooring.
Quarry/Ceramic tile have been successfully resurfaced on many projects without removal of tile and setting bed. A site investigation along with cores through the entire slab will help identify the type of setting bed, the existence of any waterproofing membranes, additional toppings, or other unusual existing conditions. Water trapped within the floor will create long-term sanitation and performance problems.
Existing Epoxy Coating/Resurface
Existing seamless floors may be resealed or resurfaced from time to time due to excessive wear or the need to change the appearance or skid resistance of the floor. The existing floor should first be cleaned and degreased with a floor cleaner/degreaser. It must then be mechanically abraded with a floor-sanding machine or a steel shot blast machine to totally remove gloss. Vacuum perfectly clean. “Tack rag” area to remove dust and to soften surface. Apply coating to entire area immediately followed by subsequent epoxy coatings.
The plywood substrate must be sound and non-flexing under the expected load. Typical plywood substrate must be exterior or marine grade, new, clean, and smooth finish (NO KNOTS). Two layers with staggered joints are required. Plywood should be positively fastened to the existing surface with a high quality construction adhesive as well as a 6″ screw pattern.
Surface Preparation Standards
SSPC-SP1 Solvent Cleaning
Removal of all visible oil, grease, soil, drawing and cutting compounds, and other soluble contaminants from steel surfaces with solvent, vapor, cleaning compound, alkali, emulsifying agent, or steam.
SSPC-SP2 Hand Tool Cleaning
Removes all loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter by hand chipping, scraping, sanding, and wire brushing.
SSPC-SP3 Power Tool Cleaning
Removes all loose mill scale, loose rust, loose paint, and other loose detrimental foreign matter by power wire brushing, power sanding, power grinding, power tool chipping, and power tool descaling.
SSPC-SP5 / NACE 1 White Metal Blast Cleaning
When viewed without magnification, the surface shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products and other foreign matter.
SSPC-SP6 / NACE 3 Commercial Blast Cleaning
When viewed without magnification, the surface shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products and other foreign matter of at least 66-2/3% of unit area, which shall be a square 3 in. x 3 in. (9 sq. in.). Light shadows, slight streaks, or minor discolorations caused by stains of rust, stains of mill scale, or stains of previously applied coating in less than 33-1/3% of the unit area is acceptable.
SSPC-SP7 / NACE 4 Brush-Off Blast Cleaning
When viewed without magnification, the surface shall be free of all visible oil, grease, dirt, dust, loose mill scale, loose rust, and loose coating. Tightly adherent mill scale, rust, and coating may remain on the surface. Mill scale, rust, and coating are considered tightly adherent if they cannot be removed by lifting with a dull putty knife.
SSPC-SP10 / NACE 2 Near-White Blast Cleaning
When viewed without magnification shall be free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products and other foreign matter of at least 95% of each unit area. Staining shall be limited to no more than 5 percent of each unit area, and may consist of light shadows, slight streaks, or minor discolorations caused by stains of rust, stains of mill scale, or stains of previously applied coatings. Unit area shall be approximately 3 in. x 3 in. (9 sq. in.).
SSPC-SP11 Power Tool Cleaning to Bare Metal
When viewed without magnification, the surface shall be free of all visible oil, grease, dirt, dust, mill scale, rust, paint, oxides, corrosion products, and other foreign matter. Slight residues of rust and paint may be left in the lower portion of pits if the original surface is pitted. The surface profile shall not be less than 1 mil (25 microns).
SSPC-SP12 / NACE 5 Surface Preparation and Cleaning of Steel and Other Hard Materials by High- and Ultra High- Pressure Water Jetting Prior to Re-coating
This standard requires water jetting at high- or ultra high-pressure to prepare a surface for re-coating using pressure above 10,000 psi. Water jetting will not produce a profile; rather, it exposes the original abrasive-blasted surface profile. Water jetting shall be performed to meet four conditions: WJ-1, WJ-2, WJ-3, and WJ-4, and a minimum acceptable surface shall have all loose rust, loose mill scale, and loose coatings uniformly removed.
SSPC-SP13 / NACE 6 Surface Preparation of Concrete
Provides requirements for surface preparation of concrete by mechanical, chemical, or thermal methods prior to the application of bonded protective coating or lining systems.
SSPC-SP14 / NACE 8 Industrial Blast Cleaning
Removal of all visible oil, grease, dust and dirt, when viewed without magnification. Traces of tightly adherent mil scale, rust, and coating residues are permitted to remain on 10% of each unit area of the surface if they are evenly distributed. Shadows, streaks, and discoloration caused by stains of rust, stains of mill scale, and stains of previously applied coating may be present on the remainder of the surface.