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Updated: Dec 12, 2025

Experimental Protocol to Determine the Chloride Threshold Value for Corrosion in Samples Taken from Reinforced Concrete Structures
Published on: August 31, 2017
Characterizing concrete corrosion below sewer tidal levels at chemically dosed locations
Shima Taheri1, Martin Ams2, Heriberto Bustamante3
1Department of Physics and Astronomy, Macquarie University North Ryde, NSW 2109, Australia; Department of Earth and Environmental Science, Macquarie University North Ryde, NSW 2109, Australia.
Abstract:
Unexplainable concrete softening below the water line has been observed by Sydney Water in their gravity sewer network, some of which is subjected to corrosion control methods using chemical ferrous chloride (FeCl2) dosing of the wastewater. We applied a combination of physical and chemical tools to determine the properties of the top 20 mm of concrete cores recovered from sewer pipes. These techniques consist of neutron tomographic imaging, scanning electron microscopy, hardness mapping, and pH profiling. Concrete cores were collected from roof (crown), tidal (wall) and below flow regions of gravity sewer pipes of Sydney Water's wastewater system from locations that received no treatment as well as locations dosed with FeCl2. All samples showed a degree of softening of the surface exposed to the sewerage with an associated depletion in calcium concentration and reduced pH in the same regions.
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