2016 SUBSTRATE PREPARATIONS

SUBSTRATE PREPARATION METHODS FOR CONCRETE Very Course Profile Scabbling – Suitable for very aged, weak or contaminated substrates. Used in worst case scenarios and may require resurfacing. Course profile Scarifying – Suitable for aged, weak, rain damaged or contaminated substrates. Resulting surfaces may require resurfacing. Medium profile Abrasive Blast – Most common preparation method and is essential for off-form or high strength concrete.

SUBSTRATE PREPARATION METHODS CONCRETE - Mechanical Methods Fine profile Grinding – Suitable for removal of minor/moderate substrate contamination. Not a preferred method as if not done correctly there is a risk of polishing the substrate and filling the concrete pores. Original profile Scaling – Considered a pre- preparation method and is excellent for removal of hard coverings and adhesives or old membranes. Substrates should be abrasive blasted after treatment to open the concrete pores.

Acid etching should only be applied when there is absolutely no alternative. Acid etching should be done with a 10-15% dilution of concentrated hydrochloric acid and water. Always add the acid to water NOT the other way around. Acid will penetrate the concrete and will cause the neutralization of the alkaline protection of the reinforced steel in the concrete. Substrates must be completely rinsed with clean water as soon as the reaction has ceased to remove all acid salts and residual acid. Acid etching is ineffective in the removal of grease and oil type contaminations. SUBSTRATE PREPARATION METHODS CONCRETE - Acid Etching

HIGH PRESSURE WATER BLASTING HPW Washing is normally limited to nozzle pressures and should be limited to 35 mpa (5000 psi) and will clean the concrete surface however will have little effect on the mechanical properties of the concrete. HPW Detergent Washing is a highly effective preparation for removal of oil based contaminants HPW Blasting will have little effect of concrete greater than 30 MPa compressive strength. HPW Blasting is ineffective for the treatment of off-form concrete. SUBSTRATE PREPARATION METHODS CONCRETE – High Pressure Water

It is impossible to remove grease and oil contamination from concrete surfaces. Most effective process of treatment involves:- SUBSTRATE PREPARATION METHODS CONCRETE – Degreasing 1.Wash with Industrial Degreaser (only required with high contamination). 2.High pressure detergent water wash. 3.High pressure water rinse to force residual oil/grease deep into the matrix of the concrete. 4.Remove excess surface water and apply a two-part epoxy primer. Mechanical substrate preparation methods other than possibly scabbling or scarifying are ineffective in grease and oil removal.

Consolidation of weak surfaces is risky since depth of the integrally weak layer is unknown. Dusting surfaces and light/moderate rain damaged surfaces may be able to be consolidated using two coats of an epoxy primer such as Hydrapoxy. Consolidation of old aged concrete or severely rain damaged concrete is unlikely to be successful and No warranties would apply to the substrate. Weak, aged or rain affected concrete substrates Should be mechanically cleaned. SUBSTRATE PREPARATION METHODS CONCRETE – Consolidation

SUBSTRATE PREPARATION METHODS CONCRETE – Pore Filling Concrete or masonry surfaces with very high surface porosity such as concrete masonry blocks should be treated to fill the surface voids before any liquid membrane applications. A similar recommendation applies to sheet membranes but is less critical. This type of concrete is normally weak. Void or filling pores can be achieved by bagging using an using a sand/cement slurry coat mixed with an additive such as Gripset 11y. High performance methods would be to completely render the wall with a quick setting render,

SUBSTRATE PREPARATION METHODS BRICK Bricks come in a number of different types are clay baked. High fired bricks. Very dense low permeability, and can be glossy. Frequently contain cracks from micro to 1-2 mm. These bricks are normally the ones that are coated. Best treatment is abrasive blast cleaning but is not always viable due to damage to purps. Minimum treatment is bagging the wall with a bag system mixed with Gripset 11y. Medium fired types – ‘finish’ and ‘rumbled’ Reasonable porosity with a profiled surface. Normally left in natural state or prepared as above. Any surface preparation must be a light water-blast.

SUBSTRATE PREPARATION METHODS Fibre Cement Substrate preparation is limited to sanding or vacuum cleaning. Most critical aspect is the fixing of the sheet and the gap between the sheet. Sheets must be screw fixed – NOT nailed. Joints must be sealed and a closed cell backing rod. This applies to all membranes including sheet membranes to prevent the membrane being pinched in the joint. Best system for FC decks is a sheet membrane system. Install a rubber-based tape over all sheet joints, DO NOT use a fiberglass or polyester reinforcement tape. Completely fully reinforcing decks are always the best system.

SUBSTRATE PREPARATION METHODS SCYON BOARD Substrate preparation is limited to sanding or vacuum cleaning. Scyon board is only 600 mm wide Most critical aspect is the priming of the sheet and all the sheet joints. Problem with the surface of Scyon board is if it gets rained on before the application of a liquid membrane. Sheets must be screw fixed – NOT nailed. Joints must be sealed during the fixing process by the builder. Best system for Scyon decks is a sheet membrane system. Install a self-adhesive Butynol tape over all sheet joints, DO NOT use a fiberglass or polyester reinforcement unless fully reinforcing the deck.

PRIMERS Priming has also been an issue for contractors as the same questions are always asked, do we need to prime, or what primer do we use? The simple answer is EVERYTHING NEEDS TO BE PRIMED? Priming matters as it is an essential part of the installation of any waterproofing product as is promotes bond strength, seals the surface to make the substrate more stable, protects against atmospheric moisture and osmosis and ensures a much better adhesion of the membrane system. Primers are products which allow for coating and membrane systems to adhere far greater than if it the membrane or coating was installed without primers. Primers in most cases do not need to be engineered to be durable as they are over coated with membranes, in some case primers can be engineered to have enhanced fillers or binding properties for the membrane system to work as intended so it is very important that you always use the primer recommended by the membrane manufacturer. Most water-based primers are inexpensive,

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