Services Provided
Corrosion Protection
Concrete, on its own, is an extremly durable building material and is used in many applications within the building and civil engineering industries. Unfortunately, it cannot withstand the effect of tensile stresses on its own and in order to achieve this property it requires to be reinforced. This reinforcing is normally achieved by the introduction of steel into the concrete in the form of bars or rolled steel sections.
The cement that is used to produce the concrete is alkaline and while it is in this state the concrete will not deteriorate. However, due to a number of reasons, including the environment in which the concrete is situated, its alkalinity is likely to be reduced over a period of time and eventually it will become acidic. This acidity will penetrate through the concrete until it reaches the steel reinforcement, which in turn causes the steel to begin to rust. When steel rusts it expands; this produces stresses in the concrete causing it to crack and eventually break away.
The main ways by which this can be retified, or prevented, are:-
- Cathodic Protection.
- Sacrificial Anodes.
- Migrating Corrosion Inhibitors.
Cathodic protection is undertaken by passing a low voltage DC current through the steelwork of the structure. The system has to be designed by a specialist contractor. Once completed, it can be monitored remotely via a computer and the current adjusted to maintain its protective properties.
Sacrificial anodes comprise zinc metal surrounded by a highly alkaline cementitious mortar that has a pore solution pH which is sufficiently high for corrosion of the anode to occur. The anodes can be installed into the repairs or, depending on the type, they may be inserted into the concrete at regular spacing and linked together with a wire that is attached to the reinforcing bars to ensure electrical continuity.
Migrating corrosion inhibitors are single component low viscosity clear liquids that are applied by spray or brush to the surface of the concrete. The liquid penetrates the concrete and forms a thick monomolecular chemical protective film on the surface of the steel reinforcement.
Grade 2 Structural Repairs Ltd have undertaken a number of projects invloving the use of anodes and migrating corrosion inhibitors.