M-Coating shaft rehabilitation has stood the test of time

Category: General News

One big project proved once again the power of our M-Coating system.

Concrete inspection shaft

Concrete inspection shaft

Brick-built shaft

Brick-built shaft


High corrosion requires reliable technique

In 2010 the city of Dortmund had to rehabilitate two shafts that were hugely attacked by corrosion. This work required great technical experience and powerful tools. That is why HERMES Technologie and our M-Coating system were called. The two shafts were differently built: one with concrete, the other one with bricks but that was no problem for our polyvalent equipment.

From the start to the recurrent after-work controls, the MPA NRW of Dortmund monitored every steps of the work

Step one: cleaning

More than ever, the cleaning was very important due to the state of the shafts. Our water cleaning tool TSSR got remarkable results of the concrete shaft. On the brick-built one, the cleaning needed more work due to the material. So our sand and water blasting tool, the HDS-Jet, prepared the surface for the coating.

Step two: coating

As usual for this kind of application, the best mortar to use was the ERGELIT KS1. It was sprayed by the centrifugal spraying head to a thickness of 30 mm for the concrete shaft because of the deep corrosion level (50 mm). The brick-built shaft needed only 10 mm of mortar.

Today’s state

5 years later, the shafts are still in a very great condition. Visual inspections were made by the MPA and stated that no corrosion and no leak were visible. All type of controls according to the following European and German standards took place: DIN EN 12504, EN 154:1999, DIN EN 14630 and DIN EN 1936. The results are good and validated by the MPA NRW.
This reference confirmed the 33 + years of experience in sewer works from HERMES Technologie.

Some numbers:

  • Compressive strength before: 20 N/mm² ; 5 years after: 46 N/mm²
  • Bond strength ~ 2,50 and 2,19 N/mm², well above the figures from 2010
  • Carbonation depth: 0 mm
  • Open porosity around 9,69 % (very shallow depth)
  • Only 2 operators and 3 hours were required for the work