Webercem HB Bondcoat is a single-component polymer-modified, cementitious bonding aid. It requires only the addition of clean water to produce a bonding slurry for Webercem HB30, Webercem HB40 and Webercem lightweight mortars.

This product has been formulated to comply with the requirements of BS EN 1504-3 for a bonding primer.

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• Features & Benefits
• Preparation
• Mixing
• Application

Features & Benefits

• High initial grab to improve the build of the repair mortar and promote the bond to the concrete
• This product has been formulated to comply with the requirements of BS EN 1504-3
• Contains fibres for improved thixotropy
• Cementitious, contains no solvents
• Single-component; simply mix with water

Preparation

Concrete substrates must be adequately prepared by use of scabbing, needle gunning or other means, as appropriate. Oil and grease must be removed by steam cleaning together with suitable detergent. Any contaminated concrete must be removed. All damaged concrete should be cut back to a sound surface and at least 15mm behind any exposed reinforcement. The edges of the repair should be cut perpendicular to the surface of the repair.

• Note: Disc cutting is not recommended due to hazardous respirable crystalline silica that can be produced

New concrete must be at least 14 days old. Thoroughly saturate the concrete but remove excess water.

Steel Substrates:

Steel substrates should be cleaned by a grit blasting treatment to Swedish Standard Specifi cation SA 21/2 (equivalent to BS 7079-A1) immediately prior to bonding. However, in many instances where corrosion is absent, wire brushing to obtain a clean surface may be adequate.

Where exposed reinforcement is contaminated with chloride or other material which may cause corrosion, the whole of the circumference of the contaminated reinforcement shall be cleaned in accordance with BS EN 1504-10 Clause 7.3.2 (e).

Mixing

Use a forced action mixer or a MR4-120B paddle with a high powered low speed drill. Mix 20kg of Webercem bondcoat with 8 litres of clean water by adding the weber cem bondcoat powder to water and stirring continuously to a brushable slurry consistency.

For small quantities mix 2½ parts Webercem bondcoat with 1 part clean water by volume. Use a palette knife or a rigid fl at stick and mix to a creamy consistency. The ideal mix should allow a stipple finish.

If the mix stiffens too quickly, it can be remixed easily with no more water. Extra water should not be added.

Application

For steel reinforcement: Using a stiff bristle brush, apply one full unbroken coat of Webercem bondcoat to the steel, ensuring that the backs of the reinforcing bars are fully coated with at least a 2mm thickness of the Webercem Bondcoat.

To damp concrete: Apply Webercem bondcoat to an area that can be overlaid with the appropriate HB mortar within 20 minutes.

Apply immediately after mixing to the prepared concrete surface.

Use a stiff brush to scrub the slurry well into the surface. Stipple finish the applied slurry coat. Overcoat the steel if it has been used as a holding primer.

Place the mortar onto the slurry while it is tacky. In hot weather the slurry will dry quickly once it is applied (ie within 15 minutes) and it is prudent to mix the mortar first ready for application.