Thermodynamic and kinetic study of LC3 cement performance during sulfate attack

Document Type : Research Article

Authors

1 Department of Geotechnical Engineering and Water Engineering, Shahid Rajaee Teacher Training University

2 Shahid RajaeeTeacher Training University

3 Shahid Rajaee Teacher Training University

Abstract

In this study, the kinetics role of gypsum is evaluated in limestone calcined clay cement (LC3) during exposure to a 30 g/l [[EQUATION]] solution. Previous studies considered the chemical aspects of cement, and seldom of them take into account the kinetics aspects. In this study, geochemical code PHREEQC along with kinetics and rate keyword data block was used to evaluate the chemical and kinetics aspects of cementitious material, simultaneously. The simulation results are compared with experimental and modeling results to the confirmation of present model accuracy. Kinetics diagrams for samples with the various cement replacement percentages and ratio of calcined clay to cement replacement percentage (CC/CC+L) are evaluated to get more information about the kinetics path of gypsum production during sulfate attacks. The results show that three levels can be considered as the kinetics change of gypsum. The first stage of gypsum production gets longer by the increment of CC/CC+L ratio. It means that gypsum is produced with delay for the mixture with a higher CC/CC+L ratio. The availability of more aluminum ions due to the presence of more calcined clay leads to the continuation of ettringite production instead of gypsum formation. In LC3 cement the maximum amount of produced gypsum is reduced as well as the rate of gypsum production. The stress due to the gypsum formation is applied to the cement matrix with the delay because of the prolongation of the first stage.

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Amirkabir Journal of Civil Engineering
Volume 56, Issue 6
2024
Pages 729-748

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