Determination of water permeability for cementitious materials with minimized batch effect

TL;DR

This study compares various permeability determination methods for cementitious materials using a standardized specimen to reduce batch effects, finding that the beam bending method yields the most accurate results.

Contribution

It introduces a standardized specimen preparation approach to minimize batch effects and evaluates multiple permeability methods against moisture transport models.

Findings

Beam bending method closely matches measured moisture loss.

Other methods are affected by microstructure changes due to drying or rewetting.

Standardized specimen reduces variability in permeability measurements.

Abstract

Values of water permeability for cementitious materials reported in the literature show a large scatter. This is partially attributed to the fact that materials used in different studies are different. To eliminate the effects of cements, specimen preparation, curing conditions and other batch effects, this study employs a long cylindrical cement paste to prepare all specimens for a variety of permeability determination methods, such as beam bending, sorptivity, Katz Thompson and Kozeny Carman equations. Permeabilities determined by these methods are then used in a moisture transport model. Compared with the measured mass loss curves, we found that permeability determined by the beam bending method provides much closer results to the measured ones than other methods. The difference results from that the saturated specimen is used in the beam bending method while specimens in other methods are dried (or rewetted). As already shown in the literature, the microstructure of the dried or rewetted specimens is altered and different to the original microstructure of the water saturated specimens.