Restoration of Corrosion Protection

One of the most important tasks of civil engineers to ensure the durability of structures is the corrosion protection of steel elements. DSI offers efficient and advanced methods for restoring the corrosion protection of both prestressing and reinforcing steel.

Vacuum Grouting

Restoring corrosion protection of prestressing steel
Where ducts are not completely filled with cement grout, subsequent grouting must be carried out. This can be accomplished by vacuum grouting. The advantage of this procedure is that regrouting of the duct requires only one drilled hole for each void.

Special devices and techniques have been developed by DSI for careful drilling of ducts to avoid damaging the prestressing steel. The volume of the void is measured by creating a vacuum, which also sucks the grout into the void. A comparison between the measured volume of void and the amount of grout consumed provides a control measure on the success of the operation.

DSI Reference: Bridges on the Brenner Highway, Austria

Cathodic Protection

Restoring corrosion protection of reinforcing steel
Degradation of ancient building materials, prolonged exposure to environmental influences and uneven settlements make the strengthening of historic buildings unavoidable.
Besides the traditional corrosion protection methods in which the carbonized or the chloride-contaminated concrete is mechanically removed and replaced with new alkaline concrete, DSI has employed a highly reliable electrochemical corrosion protection method: cathodic protection (CP).

A low intensity direct current (5-20 mA/m 2 ) is continuously applied between the reinforcement (the cathode) and a durable anode (made of materials such as titanium), which is embedded into a cementitious overlay on the old concrete surface. The efficiency of the CP measure is controlled through potential measurements on the embedded reference cells. This protection measure is more economical than traditional methods, as only the mechanically damaged concrete must be removed, whereas the chloride-contaminated concrete may be left undisturbed.

DSI Reference: Outer Noesslach Bridge, Brenner Highway, Austria