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Computers and Concrete
  Volume 16, Number 6, December 25, 2015 , pages 865-880
DOI: https://doi.org/10.12989/cac.2015.16.6.865
 


Modeling of damage in cement paste subject to external sulfate attack
Chuansheng Xiong, Linhua Jiang, Yan Zhang and Hongqiang Chu

 
Abstract
    This study aimed to develop models of sulfate diffusion and ettringite content profile in cement paste for the predication of the damage behavior in cement paste subject to external sulfate. In the models, multiphase reaction equilibrium between ions in pore solution and solid calcium aluminates phases and the microstructure changes in different positions of cement paste were taken into account. The distributions of expansive volume strain and expansion stress in cement paste were calculated based on the ettringite content profile model. In addition, more sulfate diffusion tests and SEM analyses were determined to verify the reliability and veracity of the models. As the results shown, there was a good correlation between the numerical simulation results and experimental evidences. The results indicated that the water to cement ratio (w/c) had a significant influence on the diffusion of sulfate ions, ettringite concentration profile and expansion properties in cement paste specimens. The cracking points caused by ettringite growth in cement paste specimens were predicted through numerical methods. According to the simulation results, the fracture of cement paste would be accelerated when the specimens were prepared with higher w/c or when they were exposed to sulfate solution with higher concentration.
 
Key Words
    modeling; sulfate diffusion; ettringite profile; volume strain; cement paste
 
Address
Chuansheng Xiong, Linhua Jiang, Yan Zhang and Hongqiang Chu: College of Mechanics and Materials, Hohai University, 1 Xikang Rd., Nanjing, China
 

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