Characterization methods for sulfate ions diffusion coefficient in calcium sulphoaluminate mortar based on AC impedance spectroscopy. (28th June 2021)

• Record Type: Journal Article
• Authors: Hou, Wei; He, Fuqiang; Liu, Zanqun
• Is Part Of: Construction & building materials. Volume 289(2021)
• Publication Date: 2021-06-28
• Subjects: Diffusion coefficient -- Calcium sulphoaluminate cement -- AC impedance -- Critical pore diameter threshold; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123169
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: AC impedance method can determine the diffusion coefficient of sulfate ions in CSA mortars. Immersion and electro-migration methods can not measure the diffusion coefficient. The critical pore diameter that influences the diffusion coefficient is approximately 40 nm. The diffusion coefficient is linear to the cumulative porosity of diameter larger than 40 nm. Abstract: Calcium sulphoaluminate (CSA) cement has higher impermeability and resistance to sulfate attack than Portland cement. Determining the diffusion coefficient of sulfate ions can evaluate and predict the service life of the concrete. This paper proposes a new method to measure the diffusion coefficient of sulfate ions in CSA cement mortar by alternating current impedance (AC impedance). Results indicate that the immersion and electro-migration tests are not suitable for measuring the diffusion coefficient of sulfate ions in the CSA cement mortar, while the AC impedance method provides more accuracy. In addition, the critical pore diameter that influences the diffusion coefficient of SO4 2- is determined to be approximately 40 nm by low-field nuclear magnetic resonance. The diffusion coefficient is also linearly related to the cumulative porosity of diameter larger than 40 nm in the CSA mortars.