Performance of Sewer Concretes with Calcium Sulpho-Aluminate Cement and Portland Cement Blends: Field and Laboratory Studies

Bakera, Alice Titus; Aboulela, Amr; Alexander, Mark; Bertron, Alexandra; Peyre-Lavigne, Matthieu; Meulenyzer, Samuel; Patapy, Cédric

doi:10.2139/ssrn.4409585

Cited by 2 publications

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“…DI specimens were prepared as per SANS 3001-CO3-1 [19]. The tests, i.e., the Oxygen Permeability Index (OPI) test and Water Sorptivity Index (WSI) test, were performed per SANS 3001-CO3-2 [20] and the UCT DI manual [17], respectively 2.4 Specimen preparation for exposure and monitoring Specimens for exposure were prepared and exposed for monitoring, as indicated in Bakera et al [21]. The monitoring included visual observation, mass and dimension measurements, and surface pH measurements, which were conducted monthly to quarterly for about two years.…”

Section: Laboratory Quality Control Testsmentioning

confidence: 99%

“…Two sewer sites in the City of Cape Town in South Africa were considered for concrete exposure, i.e., Northern Area Sewer Manhole 19 (NAS) and Langa sewer pump station manhole (LPS). Detailed information regarding NAS is provided by Bakera et al [21], and those for LPS in Kiliswa [3]. LPS manhole for exposure is situated between two pump stations; because of the periodic pumping effect, specimens experience wetting and drying cycles, i.e., sewer hydraulic actions.…”

Section: Sewer Site Background and Environmental Conditionsmentioning

confidence: 99%

“…As in Bakera et. [21], SEM-BSE and XRD analyses were conducted, while QEMSCAN analysis was as in Bakera and Alexander [22].…”

Section: Sewer Site Background and Environmental Conditionsmentioning

confidence: 99%

“…However, with acid penetration, secondary ettringite is formed in the transition zone from the gypsum and calcium aluminate hydrate reaction [47]. As a result, the transition zone in the concrete microstructure is complex to define due to ettringite superposition, i.e., ettringite originally present before deterioration and ettringite formed subsequently after sulphate penetration [21].…”

Section: Csa Binder Systemmentioning

confidence: 99%

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

Bakera,

Alexander

2024

Mater Struct

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Section: Laboratory Quality Control Testsmentioning

confidence: 99%

Section: Sewer Site Background and Environmental Conditionsmentioning

confidence: 99%

“…As in Bakera et. [21], SEM-BSE and XRD analyses were conducted, while QEMSCAN analysis was as in Bakera and Alexander [22].…”

Section: Sewer Site Background and Environmental Conditionsmentioning

confidence: 99%

Section: Csa Binder Systemmentioning

confidence: 99%

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

Bakera,

Alexander

2024

Mater Struct

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

Bakera

Alexander

2023

Preprint

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This paper provides 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. Three concrete mixes using these binders, with 0.34 w/b, siliceous pit sand, and dolomite aggregates, were prepared for two years of exposure in two sewer sites. During exposure, monitoring through visual observation, concrete surface pH, mass and thickness change was conducted regularly to observe the deterioration. At the end of exposure, microstructural analysis, i.e., Scanning Electron Microscopy, Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) and XRD analyses, were conducted to elucidate the deterioration mechanisms further. Regardless of sewer exposure conditions, the monitoring results indicated that CAC concrete had superior performance, followed by CSA, then CEM II. However, corrosion rates were accelerated when a sewer had hydraulic actions and high H2S gas concentrations (max.>300 ppm). CSA outperformed CEM II due to the presence of ettringite, while ettringite superposition in the transition zone reduced CSA performance compared to CAC concrete. Binder performances wereprimarily related to their chemistry, mineralogy, and interaction with aggregates.This paper provides 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. Three concrete mixes using these binders, with 0.34 w/b, siliceous pit sand, and dolomite aggregates, were prepared for two years of exposure in two sewer sites. During exposure, monitoring through visual observation, concrete surface pH, mass and thickness change was conducted regularly to observe the deterioration. At the end of exposure, microstructural analysis, i.e., Scanning Electron Microscopy, Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) and XRD analyses, were conducted to elucidate the deterioration mechanisms further. Regardless of sewer exposure conditions, the monitoring results indicated that CAC concrete had superior performance, followed by CSA, then CEM II. However, corrosion rates were accelerated when a sewer had hydraulic actions and high H2S gas concentrations (max.>300 ppm). CSA outperformed CEM II due to the presence of ettringite, while ettringite superposition in the transition zone reduced CSA performance compared to CAC concrete. Binder performances wereprimarily related to their chemistry, mineralogy, and interaction with aggregates.

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Performance of Sewer Concretes with Calcium Sulpho-Aluminate Cement and Portland Cement Blends: Field and Laboratory Studies

Cited by 2 publications

References 0 publications

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

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

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

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