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Computers and Concrete
  Volume 34, Number 1, July 2024 , pages 123-135
DOI: https://doi.org/10.12989/cac.2024.34.1.123
 


Numerical simulation on capillary absorption of cracked SHCC with integral water repellent treatment
Yao Luan and Tetsuya Ishida

 
Abstract
    Strain-hardening cement-based composites (SHCC) under cracked condition exhibits remarkable capillary absorption due to water ingress from multiple cracks. Surface treatment using water repellent agents is an effective way for improving water resistance of SHCC, but the water resistance may remarkably decrease when cracks penetrate impregnation depth. Another way is to add water repellent agents directly into the mixture, offering SHCC integral water repellency even if cracks form later. However, although integral water repellent treatment has been proved feasible by previous studies, there is still lack of simulation work on the treated SHCC for evaluating its durability. This study presents a simulation method for capillary absorption of cracked SHCC with integral treatment based on a multi-scale approach proposed in the authors' previous work. The approach deals with water flows in bulk matrix and multiple cracks using two individual transport equations, respectively, whereas water absorbed from a crack to its adjacent matrix is treated as the mass exchange of the two equations. In this study, the approach is enhanced for the treated SHCC by integrating the influencing of water repellency into the two transport equations as well as the mass exchange term. Using the enhanced approach, capillary absorption of water repellent SHCC under cracked condition is simulated, showing much more reduced water ingress than the untreated concrete, which is consistent with total absorption data from previous tests. This approach is also capable of simulating water spatial distribution with time in treated SHCC reasonably.
 
Key Words
    capillary absorption; integral water repellence; multi-scale modeling; multiple fine cracks; silane treatment; strain-hardening cement-based composites (SHCC)
 
Address
Yao Luan: Department of Civil and Environmental Engineering, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama-shi, Saitama 335-8570, Japan
Tetsuya Ishida: Department of Civil Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
 

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