Modelling the long term corrosion of reinforced concrete sewers

Microbiologically influenced corrosion (MIC) of reinforced concrete sewer systems is a major issue for waste water authorities world-wide. Global repair costs are estimated at billions of dollars per year. Advanced stages of corrosion may trigger structural failure with potentially serious operational, economic and societal consequences. The fundamental issues involved in concrete sewer deterioration are reasonably well-understood but much less developed is the quantitative prediction of the rate at which deterioration is likely to occur under particular operating environments. An outline is given of a current industry-sponsored research project that aims to develop a phenomenological model of the sewer corrosion process for use in estimating the reliability and the expected remaining service life of concrete sewers. The model will be based on corrosion science but to ensure relevance to use in industry it will be calibrated to field observations and specific laboratory testing. This will also involve historical records and the experience of the industry participants. Parameters of particular interest include H2S levels, temperature and humidity and the effect of odour control measures.