Surface Preparation

It's all about PREP!

The key to the overall success of all specialised applications is the preparation.

Correct substrate preparation is achieved by the various methods outlined below. A general guide to the correct technique is determined by two factors:

i) The condition of the existing substrate and the need to remove any existing coatings, or contaminants
ii) The requirements of the subsequent coatings or topping to be applied.

Captive Shot Blasting

Captive shot blasting is the profiling of the substrate by way of mechanically firing steel abrasives onto the floor surface at great force to create the desired profile for subsequent coatings. The process involves containment of the steel grit within in the body of the machine, which is drawn back and recycled for continuous use.

Captive shot blasting has been proven through studies to be the most effective form of concrete preparation. Captive shot blasting is up to 20% more effective than other methods of surface preparation such as diamond grinding.

Captive shot blasting can where appropriate be effective as a standalone profile for tiles or concrete where a decorative and/or non-slip finish is required.

Diamond Grinding

Diamond grinding is by definition the most practical and widely used method of concrete preparation, in particular where the desired finish is not compatible to the more aggressive method of profiling.

By virtue of the numerous combinations and configurations of blade selection combined with the various machinery available offers a broad range of solutions to many facets of concrete preparation, such as the removal of carpet and tile glue, the removal of cementitious screeds and toppings through to the general cleaning and removal of latent’s and preparation for subsequent finishes. Another area where diamond grinding stands alone is in the area of polishing concrete to expose the aggregate where an architectural finish is required or an ethically suitable clear finish is desired. Diamond grinding is widely specified in the rectification of undulating or rain damaged concrete.


Scarifying

Scarifying is performed by the use of a mechanically driven drum containing tungsten tipped discs which aggressively removes coatings or concrete for the preparation of the substrate to receive high build trowel on toppings or in the preparation of slab on slab toppings.

Heavy duty scarifying removes the existing substrate and exposes the underlying coarse aggregate which creates a suitable plane that will bond to the new concrete overlay or system. In general typical scarifying depths range from 3mm to 10mm. The result of scarifying is an exposed aggregate which is a clean and undamaged layer of concrete ready to provide a strong anchor for the overlay or repair material.

Acid Etching

Acid etching is the reaction of a dilute acidic solution with the surface laitance resulting in a fine sandpaper like texture suitable for over coating with thin penetrating sealers and coatings.

Acid etching by definition has in the past not been environmentally sound. The hazardous fumes associated with hydrochloric acid combined with the corrosive effect on exposed steel have led to the widespread condemnation of this method by the engineering profession.

This method has now been refined. A combination of mild organic detergents, emulsifiers and solvents results in the desired etching profile whilst not affecting the concrete matrix or having negative environmental effects.

Acid etching carried out correctly provides for excellent coating adhesion and penetration by opening up the surface of the concrete.

High Pressure Cleaning

High pressure cleaning is used in conjunction with any combination of the above methods where the relevant substrate required specific treatment for the removal of oils, staining and contaminates etc.

Conclusion

The above list of techniques is not exhaustive and it is more than likely that a repair strategy will involve a combination of methods. However, when selecting repair techniques, aspects must be considered other than just the technical.

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