Stops corrosion and extends structural life.
Our unique RAAC-Guard™ range of hybrid anodes has been developed in partnership with the NHS. RAAC-Guard™ is installed into RAAC panels or onto the surface of RAAC planks and will stop reinforcing steel corrosion in as little as 7 days. The use of RAAC-Guard™ can save the time and cost of replacing the autoclaved aerated concrete (AAC) where it is still structurally sound. With a long system lifetime, RAAC-Guard™ provides a cost effective, maintenance free method of corrosion protection.
RAAC-Guard™ is not available in all regions. Contact CPT for further advice.
The reinforcement within RAAC panels and planks is typically treated with a latex-cement coating. This coating is often found to be inconsistently applied and susceptible to degradation in the form of shrinkage, cracking and debonding. Over time this can leave the reinforcement susceptible to corrosion exacerbated by the presence of carbonation and/ or chlorides in the AAC.
Corrosion is expansive in nature but, in RAAC structures, this can be initially hidden by compression of the weak aerated concrete. However, in time the corrosion can lead to cracking and spalling of the AAC as the steel reinforcement expands and pushes out. The corrosion and its effects often propagate very quickly; so it is crucial to be proactive in assessing and fixing the issue.
CPT RAAC-Guard™ anodes feature innovative electro-chemical technology to stop reinforcing steel corrosion for up to 20 years.
Available as either RAAC-Guard™ Strip or RAAC-Guard™ SA (surface applied):
Other sizes can be fabricated on request.
The full package: CPT also supplies all the ancillary materials needed for RAAC-Guard™ installation, including wires, connectors, electrolyte and embedding mortar.
RAAC-Guard™ Strip is designed for use on wall panels.
The anodes are installed into areas of RAAC identified as being at risk of corrosion. Locations are marked up and slots cut to accommodate both the anode units and the pre-connected feeder wire.
The anodes and feeder wires are fully encapsulated in DuoCrete™ P Mortar. The anodes are then temporarily connected to a power supply using titanium wire. During the short impressed current phase an electrolyte is applied to enhance current output.
The feeder wire is then permanently connected to the reinforcing steel at which point the RAACGuard™ Strip anodes are operating in galvanic mode.
Surface mounted RAAC-Guard™ SA anodes are for internal use on wall panels and roof planks. They are designed to reduce structural impact as well as minimising the dust created during installation. RAAC-Guard™ SA anodes are installed onto areas of RAAC identified as being at risk of corrosion. Locations are marked up and the anode is applied to the surface of the panel or plank using DuoCrete™ P Mortar. The pre-connected feeder wire is either fixed to the surface of the plank or accommodated in saw cuts. To secure the anode and feeder wire in place a cementitious coating is applied. The system is temporarily powered as described above before switching to galvanic mode.
RAAC-Guard™ is a hybrid cathodic protection system. During treatment the RAAC-Guard™ unit is used as both an impressed current and galvanic anode. Initially a constant voltage power supply is used to drive a high current from the installed anode to re-passivate the corroding steel, typically this will take one week. The same anode is then connected directly to the steel to provide cathodic protection by means of a galvanic current. The requirement for a permanent power supply is eliminated. RAAC-Guard™ offers the advantages of a galvanic anode system requiring little to no maintenance.