Substrate Quality and Preparation
Concrete
Break out the concrete from around and behind the reinforcement steel in accordance with the requirements of the Product Data Sheet for the appropriate BS EN 1504-3 Classification Concrete Repair Mortar.
Steel reinforcement ( Chloride induced corrosion)
Rust, scale, mortar, concrete, dust and other loose and deleterious material which reduces bond or contributes to corrosion shall be removed to a minimum standard of SA2½.. Reference should also be made to BS EN1504-10:2003 for specific requirements.
Steel reinforcement ( Carbonation induced corrosion)
Rust, scale, mortar, concrete, dust and other loose and deleterious material which reduces bond or contributes to corrosion shall be removed to a minimum standard of C St 3 as defined in BS 7079: Part A1.The whole circumference of the exposed reinforcement shall be uniformly cleaned except where structural considerations prevent it. Final surface condition should have a faint metallic sheen finish.
Unless the cleaning is carried out immediately before application of the reinforcement corrosion protection coating, the reinforcement shall be protected against further contamination.
Steel preparation maybe carried out by removing loose rust by very thorough scraping, hand or machine wire brushing, abrasive paper/cloth, grinding or other appropriate techniques to achieve the required final surface condition.
Method and choice of cleaning shall take into account bar congestion, contact between bars, proximity to concrete substrate etc.
Extra preparation of the steel should be carried out in the area of the anode tie wire connection to provide a bright steel finish to ensure a good electrical connection. Alternatively drill a small hole in the reinforcement at both ends of the anode position to accept a mild steel self tapping screw & wrap the anode tie wires around the screws.
After removal of the rust to the required standard. Clean the steel reinforcement with a dry clean brush.
Bonding Primer/Reinforcement Coating
Bonding primer:
When a bonding primer is required apply Sika® MonoTop-610 or SikaTop® Armatec-110 EpoCem®.
Reinforcement coating:
Where a reinforcement coating is required apply Sika® MonoTop-610 or SikaTop® Armatec-110 EpoCem® .
When Sika® MonoTop-610 or SikaTop® Armatec 110 EpoCem is used as a reinforcement coating or bonding primer it is important to not allow the coating to get inbetween the connection wire and steel and act as an insulator from the zinc core.
Application Method
The location and spacing of the anodes shall be as specified by the designer (for more information refer to Design Criteria above). Anodes are typically tied on the side or beneath the exposed reinforcement as close as practical to the edge of the surrounding concrete making sure that enough space is left to fully encapsulate the anode with the Sika Embedment Mortar or Sika Monotop 412N repair mortar.
Minimum cover over the anodes/embedment mortar must be 20 mm or minimum thickness of the Concrete Repair Material for trafficked areas, 10 mm or minimum thickness of the Concrete Repair Material for non- trafficked areas.
A 20mm minimum clearance on sides adjacent to repair edge should be maintained. Where chloride contaminated concrete remains in contact with reinforcement, place Sika® Galvashield® XPT/XP2/XP4 anodes along length of reinforcement or in grid pattern at spacings recommended in Table 1 & Table 2.
Pre-wet the Sika® Galvashield® anode in a similar manner to the concrete substrate prior to the application of a repair mortar.
After pre-soaking anodes use water to mix embedment mortar or concrete repair mortar. If water is to be disposed neutralise with an acid first.
Securely fasten the anode to prepared reinforcing steel using a suitable wire twisting tool to eliminate free movement, and to ensure a good electrical connection.
Steel continuity within the patch should be verified with an appropriate continuity meter. If discontinuous steel is present, re-establish continuity with steel tie wires.
Following the anode installation, electrical connection between the anode tie wires and the clean reinforcing bar should be confirmed with an appropriate continuity meter. A value of between 0.1 – 1.0 Ohm shall be achieved.
With the anodes securely in position, begin the repair process by packing the embedment mortar between the anode and the substrate to provide a conductive path to the substrate.
Allow embedment mortar to sufficiently harden around Sika® Galvashield® XP Compact /XPT/XP2/XP4 anode before applying concrete repair mortar. If using Sika Monotop 412N, both embedment and repair can be carried out in one pass, providing layer thickness does not exceed maximum layer thickness of repair mortar.
Complete repair with the appropriate BS EN 1504-3 Classification Concrete Repair Mortar and where applicable a cementitious bonding primer.
