Services
Services
1. Concrete Repairs
A) Hand Applied Mortar
Concrete decay in many structures tends to be confined to small patches and the most cost effective solution is to use hand applied mortars. These mortars are formulated and produced by a number of specialist manufacturers including Sika, Fosroc and Weber. They are blended in differing compressive strengths to suit the parent concrete to which they are applied. Normally they require only the addition of clean water.
B) Sprayed Concrete
Concrete decay in high volume or large areas is usually repaired by using machine applied spray techniques, either wet or dry. The dry spray is the more commonly used method. The mortar is loaded into the machine as dry powder and pumped to the nozzle, at which point the water is added. This has the advantage that the spraying can be undertaken at long distances from the pump with less cleaning of the hoses that only contain dry powder.
2. Corrosion Protection
Concrete is extremely strong in compression but cannot withstand high tensile stresses. Using steel-reinforcing bars normally alleviates these stresses. However, as concrete ages, it suffers from the effect of weather and other influences that can cause micro-cracking in the surface through which moisture penetrates. When this moisture reaches the reinforcement, the mild steel starts to rust. The rusting process causes the steel to expand which widens the cracks in the concrete allowing the corrosion process to accelerate. This corrosion can be reduced or prevented with one of the following treatments: -
A) Anti-carbonation Decorative, Protective Coatings
These are brush, roller or spray-applied coatings that form a barrier between the atmosphere and the surface of the reinforced concrete. They protect the exposed concrete structure from attack by acid gases, chloride ions, sulphates, oxygen and water. They have high UV light resistance and allow water vapour to escape from within the structure.
They are available in a range of colours and can be over coated as part of cyclical maintenance regime.
B) Corrosion Inhibitors
These are brush, roller or spray-applied clear impregnations that are applied directly to the surface of bare concrete as a preventative measure to delay the start of corrosion and reduce the corrosion rate.
They penetrate through the concrete structure by gas diffusion and capillary suction to form a film around the steel reinforcement that inhibits corrosion.
C) Sacrificial Anode Systems
The galvanic anodes, which consist of a sacrificial zinc core surrounded by specially formulated cement based mortar, are installed at either the repair locations or into pre-drilled holes within the structure. Once installed, the zinc core corrodes in preference to the steel reinforcement.
D) Cathode Protection Systems
These systems use either a type of anode or a mesh, which is normally made using titanium. They are designed by a corrosion specialist engineer and installed into the structure by an approved contractor. These anodes are linked together with wires that are connected to a low voltage DC current that is then passed through the structure at a rate that mitigates corrosion activity. The system can incorporate a remote monitoring device that allows the output of the electrical charge to be varied according to the rate of corrosion within the structure.
