HOW TO PREPARE INDUSTRIAL SCALE FLOORS FOR TREATMENT
This article aims to outline some of the most common principles of surface preparation when preparing a substrate to receive a resin flooring system. Whilst outline information on the methods and equipment used to prepare surfaces is included within this guide, it is recommended that advice is sought from specialist surface preparation companies.
Surface preparation is a treatment process by which a background surface/substrate is required to be sound, clean, level and free from contaminants in readiness for application of the specified product. The process involves the cleaning of residues and texturing of the surface in readiness to receive a resin flooring system. Any residues left on the surface from old coatings, or an uneven surface, will affect the adhesion, durability and aesthetics of the resin flooring system being applied. The correct method of surface preparation is vital to ensure the efficiency of resin floors.
NOTE: In accordance with BS8204-6, surface preparation by acid etching of the concrete should not be used because of the associated health and safety implications and because the concrete surface is left saturated with water and calcareous salts which may ultimately lead to debonding or osmotic blistering of the resin flooring system.
There are four key surface preparation principles used in resin flooring applications: Shotblasting, Planing/Scabbling, Grinding and Multi-Stripping. This article summarises Shotblasting and Grinding as these are the two most popular methods used for our coatings, for further information and details on Planning/Scabbiling and Multi-Stripping please contact our Technical Department or visit www.ferfa.org.uk
This condensed article has been produced from the information contained in FeRFA’s ‘Guide to Preparing Substrates to Receive Resin Flooring and Finishing of Resin Terrazzo Systems’. For further information and full publications please visit FeRFA The Resin Flooring Association’s website www.ferfa.org.uk
The method of shotblasting involves steel abrasive (shot) being propelled at high velocity by a rotating wheel within the machine body, and then onto the designated surface to produce the desired profile. The debris is collected in a vacuum unit for disposal, and the shot is recycled for continued use.
You would select shotblasting to:
- Produce a profile for the application of resin flooring
- Texture and clean concrete, asphalt or tiled surfaces
- Remove paints and sealants.
- Create adhesion for the application of a wide range of surface finishes
- Key bridge decks and roads for surface dressing and waterproof systems.
- Prepare steel (Commercial and Swedish Standard SA2 ½)
- Remove laitance from concrete floors
- Texture and remove glaze from power floated concrete
- Re-texture and re-instate slip resistant properties
The type and size of the machine selected will determine production rates achievable and degree of profiling required for the specified material to be applied.
Surfaces suitable for shotblasting include:
- Any hard composition surface that does not exhibit multiple layers of materials or contaminants. i.e. Concrete, Steel, Terrazzo.
- Asphalt surfaces – Note:- with all bituminous compounds, heat and size of the area must be considered. This is not a surface which is considered as a suitable substrate for a resin flooring system.
Due to the nature of the operation, Shotblasting will produce a lining effect commonly known as tramlining. This can be minimised with operator experience but may be still be visible even following application of floor coatings. Shotblasting will also highlight surface defects in the surface being prepared, and again these defects may be visible in thinner resin coatings. This is particularly important to note when applying to old concrete substrates. Shotblasting cannot be applied to wet or damp substrate conditions, and for optimum results, requires a smooth even surface.
Shotblasting will not effectively remove:
- Soft composition screeds
- Sticky/bituminous materials
- Materials in excess of 500 μm thickness
The grinding process is provided by diamond, tungsten or resin bonded discs or plates which are secured to single or multiple heads and rotate in a circular motion. Selection of the correct diamond or resin bonded plate is essential to achieve the correct combination for smoothing, preparing and cleaning. Grinding machines are designed for wet or dry operation and to tackle a wide variety of applications including fast grinding on uneven or tough surfaces. The type and size of the machine selected will determine achievable production rates in terms of area, speed and the degree of profiling required for the specified material to be applied. All grinding machines should be designed to be used with dust extraction.
You would select grinding to:
- Smooth and clean concrete, asphalt, stone and terrazzo
- Remove paint and coatings, thin adhesives, latex and levelling compounds
- Remove elastomeric systems
Surfaces suitable for grinding:
Grinding can be applied effectively to concrete, stone, resin terrazzo and asphalt.
- Metal bonded discs/plates for general grinding operations
- Polycrystalline Diamond discs (PCD) for removal of adhesives and elastomeric systems
Key considerations for grinding:
Grinding an uneven surface will skim across the high spots (peaks) and not touch the lower ones (troughs) unless the surface is reduced to the lowest composition first. Certain types of machines may produce a swirling effect on the surface which may be evident when applying thinner resin coatings to the prepared substrate.
This process is used to ‘dry’ the background surface/substrate or to heat the background surface/substrate in preparation to receive the specified resin flooring system. Specialist drying machines produce hot air which is applied to the surface/substrate. The process does not draw out surface contaminants, traditionally associated with ‘Hot Compressed Air Treatments’ which produce gas and air under pressure, and have environmental and safety issues.
REMOVAL OF OIL CONTAMINATION
Floors within many industrial environments are exposed to oils, hydraulic fluids, fats and grease that over time can soak deep into the substrate. Mechanical surface preparation alone may not fully remove these contaminants, which will either remain visible or they can be invisible but drawn up to the surface by capillary action when the substrate is coated. When there is clear evidence that mechanical surface preparation has not fully removed the contaminant or concerns exist about invisible deep contamination, it is often prudent to use a good quality industrial degreaser / oil remover to help breakdown the contamination. These products should be applied in line with manufacturer instructions, but the key is to always allow sufficient time for the product to break down the contamination. The treated area should then be washed down and potentially cleaned again using a PH neutral industrial cleaner to remove all residues.
Should evidence of contamination or concerns remain, advice should be sought from the Technical Department regarding an appropriate primer/coating system.