Quality surface preparation is required for concrete slab overlays including coatings and toppings.
FCS Concrete Repairs are experts in surface preparation methods and remediation systems.
FCS Concrete Repairs is a member of the International Concrete Repair Institute which provides the following Concrete Surface Preparation chip set to provide technical guidance in the standards required for various applications as detailed below.
The processes generally used to achieve these standards of preparation from very fine CSP 1 to very course CSP 10 are:
- Acid Etching
- Needle Scabbling
- Turbo & Wet and Dry Abrasive Blasting
Concrete grinding is a mechanical method of removing concrete, glues, vinyl and other contamination with abrasives such as carbide, diamond and steel installed on discs at the base of the machine which rotate horizontally.
Diamond grinding provides a clean, level and smooth surface suitable for multiple floor coating systems, usually carried out with full vacuum extraction that will significantly reduce dust produced by the grinding process.
Acid Etching of concrete is a chemical treatment to the top layer of the concrete to dissolve the surface. This can be applied at rates of time to produce light, medium or heavy profiles.
Hydraulic or pneumatic scaling guns drive steel needles into the concrete surface.
Abrasive Blasting means propelling a stream of abrasive material at high speed against a surface using compressed air, liquid, steam, centrifugal wheels or paddles to clean, abrade, etch or otherwise change the original appearance or condition of the surface.
Abrasive Blasting may be used for surface preparation prior to the application of protective coatings or to remove degraded material before concrete remediation works are carried out.
FCS Concrete Repairs are experienced in all forms of Abrasive Blasting (commonly known as “Sandblasting”) including the following:
- Dry Abrasive Blasting
- Wet Abrasive Blasting
- Turbo Blasting
Dry Abrasive Blasting involves propelling a stream of abrasive material at high speed against a surface to remove surface coatings including paint, carry-out surface preparation, remove degraded concrete in preparation for concrete repairs, roughen a concrete surface to assist in bonding and remove oxidisation (rust).
Wet Abrasive Blasting involves propelling a light stream of water with abrasive material at high speed against a surface to remove surface coatings, carry-out surface preparation, remove degraded concrete in preparation for concrete repairs, roughen a concrete surface to assist in bonding, decontamination of surfaces. This process eliminates dust, reduces media breakdown and creates a lubricating effect which protects the surface and cleans media and dust from the surface during the process. Surfaces are clean and ready for specialised coatings and painting. Different grades of media and variable water rates can be combined to achieve the optimal finished surface.
The Turbo Blasting system of abrasive blasting prevents the spread of air-borne particulates into the atmosphere and is a proven safe and cost-effective method for the removal of lead paint, asbestos and hazardous coatings with no messy chemicals and no dusty sandblasting.
Conventional blasting media are mixed with water in a pressure vessel. Water pressure from an internal pump forces the mixture under pressure from the vessel to the compressor-generated airstream where it is accelerated towards the blasting nozzle. The quantity and pressure of the abrasive mixture is adjustable at any time resulting in a very controlled blasting process. The result is a versatile, economic and environmentally safe wet abrasive blasting process.
The choice of media is important and depends on the nature of the application.
FCS Concrete Repairs will consider the following factors when making recommendations on the media which is suitable for the application:
- Size of particles required for the application
- Shape of particles required for the application
- Density of material required
- Hardness of material required
- Friability of material required
- Environmental considerations
7. Safety considerations
Choice of media grain shapes is a key factor in determining how aggressive the process needs to be and what standard of finish to the underlying surface will result. Shapes include:
- Hexagonal platy
- Hexagonal crystals
- Spherical beads
- Block like, sharp edges
- Fine powder
- Block like
- Angular, sharp edges
- Sub-round to angular
- Sub-round to round
- Angular to sub-angular
- Angular, multi-faceted
Media commonly used includes:
- Aluminium Oxide – widely used abrasive in blast finishing and surface preparation and is an extremely sharp, long-lasting blasting abrasive.
- Crushed Glass Grit – the angular nature of crushed glass grit allows for aggressive surface profiling and removal of coatings and surface contamination.
- Glass Beads – produce a much smoother and brighter polished finish.
- Garnet – a hard and heavy abrasive with larger grains which cut fast and finer grains which are used for finer finishes.
- Silicon Carbide – the hardest blasting media available and has allows for high speed cutting.
- Plastic Abrasive – delivers quick stripping rates and consistent quality and is ideal for stripping coatings and paint.
- Pumice – used chiefly as a mild abrasive and is ideal for less aggressive processes where surface protection is important.
- Steel Shot – preferred method for cleaning, stripping and improving all metal surfaces. The rounded ball shape gives a smooth compacted polished surface.
- Steel Grit – offers a very fast method for removing surface contaminants from steel.
- Corn Cob – a soft media which offers excellent cleaning and stripping properties without damage to soft substrates including timber.
- Walnut Shell – offers aggressive stripping or cleaning without damage to the underlying surface.
- Sodium Bicarbonate – cleaning media for removal of contaminates without damaging the underlying surface.