Recommendations and interpretations for the tortuosity and pore-connectivity parameter in undamaged cement-based materials

Abstract

Unsaturated transport properties, such as hydraulic conductivity (K), are commonly viewed as durability parameters for cement-based materials. Measuring K experimentally, however, is challenging due to high-pressure requirements at low degrees of saturation. For this reason, analytical expressions for hydraulic conductivity are often employed. Possibly the most widely used model for this purpose is the van Genuchten–Mualem equation. Usage of this equation requires employment of the tortuosity and pore-connectivity parameter I, which has significant implications on K. Often, a default value of is used, which leads to misrepresentation of K at low degrees of saturation. Recent works have identified the need for proper estimation of I, however uncertainty as to the realistic range for I still exists. In this paper, recommended ranges of I are developed for undamaged cement-based materials using analytical modeling based on physical realizations of unsaturated hydraulic properties. Interpretations of I are then presented based on the derived models.

Keywords:

• Cement-based materials
• transport properties
• unsaturated moisture transport

Acknowledgments

This work was conducted at the Department of Mechanical Engineering at Aalto University. Support from the department throughout this work is greatly acknowledged.

Notes

1. Since , this bound may also be interpreted as