Geometric tortuosity model of pores in concrete composite materials.

The geometric tortuosity of pores is a critical parameter for assessing the transport characteristics of eroding agents in concrete. Based on the porous, multiphase, and multiscale features of concrete composite materials, this paper establishes a model for geometric tortuosity of pores in concrete composite materials, correlating it with water-cement ratio, volume fraction and shape factor of aggregates, and quantitative analysis is conducted on the influencing factors of tortuosity. The results demonstrate a close alignment between the developed geometric model and experimental results obtained through Mercury Intrusion Porosimetry (MIP). The quantitative analysis reveals that the geometric tortuosity of pores in concrete composite materials increases with an increase in aggregate shape factor and aggregate volume fraction, while it decreases with an increase in water-cement ratio. For instance, as the aggregate shape factor increases from 1.0 to 3.0, the tortuosity of mortar increases from 8.42 to 25.28, and the tortuosity of concrete rises from 10.41 to 93.69. Similarly, as the water-cement ratio rises from 0.2 to 0.6, the tortuosity of hardened cement paste, mortar, and concrete decreases from 13.68, 18.22, and 29.33 to 7.23, 9.42, and 14.76, respectively. Furthermore, an increase in aggregate volume fraction from 0.1 to 0.5 leads to an increase in the tortuosity of mortar from 12.29 to 13.79 and the tortuosity of concrete from 18.08 to 22.76. • A model proposed for the geometric tortuosity of concrete. • A model reflected the time-varying characteristics of concrete microstructure. • A close alignment between the developed geometric model and MIP test results. [ABSTRACT FROM AUTHOR]