In situ concrete sewer performance: comparison of Portland cement, calcium sulfoaluminate cement, and calcium aluminate cement

This paper seeks to provide a better understanding of the performance of calcium sulfoaluminate cement (CSA) in comparison with calcium aluminate cement (CAC) and Portland-limestone cement, CEM II A/L 52.5 N (CEM II) in live sewer environments, thereby providing rich field data for enhancing sewer concrete design. Three concrete mixes using these binders, with 0.34 w/b, siliceous pit sand, and dolomite aggregates, were prepared and exposed for 26 months in two sewer sites. Visual observations, measurements of concrete surface pH, and mass and thickness change were conducted regularly to observe deterioration. After exposure, microstructural analyses based on SEM, QEMSCAN, and XRD were conducted to clarify the deterioration mechanisms further. Regardless of sewer exposure conditions, the results indicated that CAC concrete had superior performance, followed by CSA, then CEM II. Sewer hydraulic action and high H2S gas concentrations (max. > 300 ppm) caused accelerated corrosion rates. Binder performances were primarily related to their chemistry, mineralogy, and aggregate interaction.