Strengthening and concrete repair of the columns of the archway at Kentmanni 10.

Extract from the expert assessment: “The lower parts of the existing reinforced concrete columns of the archway have deteriorated. This is spalling of reinforced concrete caused by corrosion of the steel. In the lower parts, the reinforcing bars are already corroded in layers, which means that the outer layer of steel has started to flake off and the bar diameter has therefore decreased. The existing concrete is relatively porous. During the inspection, concrete carbonation was also tested with phenolphthalein. While the environment inside concrete is generally highly alkaline, carbonation makes it more acidic and starts to promote steel corrosion. The test showed that carbonation has progressed beyond the reinforcement. Consequently, the columns need to be protected again over their entire extent.

For the repair, the columns must be excavated down to the foundation. The top of the foundation is expected to be no deeper than 1 m. The works must take into account closing the street and reinstating the surfacing. The columns also need additional reinforcement to meet current requirements for vehicle impact loads. All loose parts are removed and the surfaces are cleaned by sandblasting. The corners of the columns are demolished. New reinforcing bars D=25 are installed in the corners and tied with U-shaped stirrups D=10, which are also anchored into the existing column in the middle. Reinforcement strength class B500. Concrete strength class >= C45/55, exposure class XC4+XD3+XF4. Minimum concrete cover to reinforcement 40 mm.”

Drawing according to which the columns were repaired and strengthened:

For the works, we used Sakret AS shotcrete.