Enhancing Maintenance and Sustainability of Concrete Sewers Using a Predictive Service Life Approach

The service life of a sewer is often set at around 100 years, regarded as a sufficient operational period without significant repairs being required. However, sewer concrete may experience severe deterioration, leading to structural and functional failures. 40% of failures can be attributed to biogenic acid corrosion, a chemical reaction between biologically produced sulfuric acid and concrete, leading to a loss of structural integrity and performance. Consequently, service life prediction models are needed for sewer management. Numerous models have been developed, but most remain ineffective and complex. The most common and widely used model is the Life Factor Method (LFM), but this model is limited when concrete with modern, high-performance binder systems and various reactive aggregates are used in different sewer environments. This paper presents further development of the LFM and applies it to predict the performance of different concrete mixes used for sewers in practice. The enhanced LFM model comprises sewer environment and material resistance factors, in which the environment factor evaluates the amount of acid produced on the exposed concrete surface in a sewer system, and the material resistance factor evaluates the amount of acid to be neutralised by the exposed concrete, considering the influence of binders and aggregates. Evaluating these two factors allows prediction of the corrosion rate of concrete with different binder/aggregate combinations when exposed to different sewer environments.