Sewerage Treatment Plant

Concrete quality at a local Sewerage Treatment Plant had come into question. The potential for corrosion of the reinforcing inside the concrete was with the feeder channels leading into the Screening Room in the Plant. While not the most glamorous of jobs – CSI had to get ‘in amongst it’ to extract perfect cores from the desired locations! Tricky work indeed!

Project Requirements

Cores were required from 3 channels leading into the Screening Room.  CSI had to arrange testing of the cores for Compression Strength, Carbonation and Chloride.

 The cores have to be extracted as per current stringent standards.  Cores have to be straight, with no cold joint and have to meet Aspect Ratio (depth:diameter).  CSI have to scan for steel reinforcing prior to coring, so no steel is hit!

Sewerage Treatment Plant
Sewerage Treatment Plant
Sewerage Treatment Plant


Testing the cores determines compression strength which gives the ultimate strength of the concrete.

Carbonation testing gives a reading on the Ph level of the concrete.  If this reading is 7 or below it can cause loss of the Passivation Threshold of the reinforcing steel.  In turn this causes corrosion.

Testing for levels of chloride is important as exposure of reinforced concrete to chloride ions is the primary cause of premature corrosion of steel reinforcement. The intrusion of chloride ions, present in contaminated water and seawater, into reinforced concrete, can cause steel corrosion if oxygen and moisture are also available to sustain the reaction.

Benefits of Solutions

When the engineer has this data, he or she can make a prediction as to the longevity of the concrete and steel and therefore the longevity of the vital Channels at the Sewerage Treatment Plant.