BWA MEMBERS PROMOTE INCREASED BONDING LEVELS TO CONCRETE.

All our BWA members have gained BBA accreditation and approval under the latest BD47/99 HA waterproofing standard. However it is felt by all concerned including the Highways Agency and local authorities that certain elements of the standard should be improved particularly the tensile adhesion of the waterproofing system to the concrete.

For any waterproofing system to provide long term protection to the concrete it must maintain adhesion and integrity throughout the service life of the system.

The current level 0.30N/mm² is in our opinion too low and in most cases on site this figure cannot be accurately measured using a standard Elcometer type adhesion tester which only reads from 0.70N/mm² and above. This figure, although higher than the current standard, is still below what is required in certain European countries.

Most contract specifications issued over the past 10 years have always stated a minimum requirement of 0.70N/m² or cohesive concrete failure as the requirement on all concrete bridges and therefore the BWA is merely adopting what is in essence standard in the market place.

The need for adequate bonding is essential for the long term performance of the system and this requirement is even more acute when the application is carried out under non standard asphalt thicknesses (ie <120mm) and in heavily trafficked or ramped/sloping areas.

The current method for carrying out adhesion testing is as follows (Elcometer 106 test equipment) This can be carried out either prior to applying the total system or after membrane installation depending upon waterproofing system. Please refer to installation guide/method statement.

1. Apply primer or bond coat to prepared surface and allow to cure as stated in manufacturer’s recommendations.
2. Install waterproofing membrane to primed surface.
3. Place a 20 or 40mm ø aluminium dolly either into the uncured membrane or once cured using Araldite Rapid or similar adhesive.
4. Isolate the test piece by cutting on the base of the dolly into the waterproofing layer.
5. Place base ring over dolly and position the Elcometer 106 Adhesion tester over dollyhead and onto base ring.
6. Hand tighten the bolt at the top of the equipment.
7. Place ratchet over bolt and turn until the failure point.
8. Take reading from side of instrument which reads 0-15N/mm². If using 40mm ø dolly divide the result by 4 as the equipment is set for 20mm ø dolly.

BWA Recommends

• Minimum acceptable tensile adhesion result for membrane to concrete increased from 0.30 to 0.70N/mm².
• 2.0N/mm² for steel surfaces or failure of zinc coating.
• At least 1 test per 500m² applied waterproofing.
• All applications to be integrity tested either high voltage dry test or alternative ‘wet’ test for sheet systems.
• All applicators to be accredited to CSCS liquid waterproofing and hold competency cards.
• ISO9001 quality assurance accreditation for all members and installers.