The 4th Asian Concrete Federation Symposium on Emerging Technologies for Structural Longevity (ACF2023- ETSL)

259 / 2022-08-05 08:57:45

Moisture diffusion behavior in cementitious materials with carboxylic acid hydrophobic agent

Hydrophobicity; Permeability; Pore structure; Hydrodynamic effects.

One of the most effective methods to improve durability of cementious materials is to resist the intrusion of water with aggressive ions by mixing with hydrophobic agent. In this study, the mechanism of carboxylic acid ammonium salt hydrophobic agent addition on hydrophobicity of cementitious materials is analyzed. The impact of hydrophobic agent on water adsorption, moisture diffusion and hydration products is investigated by experimental method. It is shown that carboxylic acid ammonium salt hydrophobic agent performs the excellent water repellence. The results of water vapor sorption isotherm show that the addition of carboxylic acid ammonium salt increases the pore volume. The simplified analytical hydrodynamic model of cone type pore and Young’s relationship is proposed to analyze the relation between characteristic parameters of pore and the permeability of cementitious materials. It can be concluded that the hydrophobicity results from the change of pore structure and the hydrophobic surface of cone region. These results provide the guidance to design the durability and develop the new hydrophobic agent used in cementitious material.

One of the most effective methods to improve durability of cementious materials is to resist the intrusion of water with aggressive ions by mixing with hydrophobic agent. In this study, the mechanism of carboxylic acid ammonium salt hydrophobic agent addition on hydrophobicity of cementitious materials is analyzed. The impact of hydrophobic agent on water adsorption, moisture diffusion and hydration products is investigated by experimental method. It is shown that carboxylic acid ammonium salt hydrophobic agent performs the excellent water repellence. The results of water vapor sorption isotherm show that the addition of carboxylic acid ammonium salt increases the pore volume. The simplified analytical hydrodynamic model of cone type pore and Young’s relationship is proposed to analyze the relation between characteristic parameters of pore and the permeability of cementitious materials. It can be concluded that the hydrophobicity results from the change of pore structure and the hydrophobic surface of cone region. These results provide the guidance to design the durability and develop the new hydrophobic agent used in cementitious material.