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Weber - Saint-Gobain

webercem bondcoat

webercem bondcoat
webercem bondcoat

Product Benefits

● Holding primer for the following repair materials: webercem HB30, webercem HB40 and webercem lightweight

● Improved bond of cementitious repair mortars to concrete

Polymer-modified cementitious bonder for repair mortars 

Product Features

About this Product

webercem bondcoat is a single-component polmer-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. 

Features and 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

Technical Services

weber's Customer Services Department has a team of experienced advisors available to provide on-site advice both at the specification stage and during application. Detailed specifications can be provided for specific projects or more general works. Site visits and on-site demonstrations can be arranged on request.

Technical helpline
Tel: (01525) 722110
Fax: (01525) 718988

Sales Contact

weber products are distributed throughout the UK through selected stockists and distributors. For UK sales enquiries and overseas projects, contact Weber's Sales office.

Sales office
Tel: (01525) 722100
Fax: (01525) 718988


Send or download the documents

You can either send the documents to an email address, or download it

Preparation & Application


Surfaces must be clean and free from laitance, mould release, oil and other surface coatings. Thoroughly soak the concrete and remove all surface water prior to application.

Concrete substrates

Concrete substrates must be adequately prepared either by use of a suitable mechanical method such as water blasting, needle gunning, or by such other means as appropriate to give a clean, freshly exposed surface. Old concrete surfaces contaminated with oil or grease require suitable preparation such as steam cleaning in conjunction with a suitable detergent. Care must be taken to ensure that the oil or grease is removed from the surface and not simply spread over a larger area. New concrete should be at least 14 days old.

Steel substrates

Steel substrates should be cleaned by a grit blasting treatment to Swedish Standard Specification SA2½ (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 Part 10: Clause 7.3.2 (e)


Use a forced action mixer or a MR4-120B paddle with a high powered low speed drill. Mix 20 kg of webercem bondcoat with 8 litres of clean water by adding the 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 pallet knife or a rigid flat 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.


To 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 2 mm thickness of the bondcoat. 

webercem bondcoat can be used as a holding primer for steel.  Apply a 2-coat application to ensure a pinhole-free coating, making sure that the back of the steel bars are fully coated.  The holding primer can be left for up to 3 days before reapplying the bondcoat the protected coated steel bars and the substrate and before applying the repair mortar.  Stipple finish the applied slurry coat.

To damp concrete substrate 

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. 

If the bondcoat primer has hardened before the mortar has been applied, it must be removed otherwise it will create a debonding layer. 

It must be removed mechanically and bondcoat applied.

Packaging, Health & Safety


webercem bondcoat is supplied in 20 kg bags.

Coverage / Yield

20kg will cover about 5-8m² depending on surface profile/texture.

Storage and Shelf Life

Shelf life is 12 months from date of manufacture if stored properly in unopened and undamaged packaging in dry conditions within the temperature range 5°C to 25°C.  If stored at higher temperatures and high humidity, the shelf life will be reduced.  Use within 3 days once the bags are opened.

Protect from frost.

Health and Safety

Contains cement (Contains chromium (VI). May produce an allergic reaction). Harmful by inhalation. Irritating to eyes and skin. Keep out of the reach of children. In case of contact with eyes, rinse immediately with plenty of water and seek medical help. After contact with skin, wash immediately with plenty of soap and water. Wear suitable protective clothing, gloves and eye/face protection.

For further information, please request the Material Safety Data Sheet for this product.