A simple air pressure gauge for unsaturated soils

This paper presents the design details of a simple compressible air column pressure gauge system. The main components of this pressure gauge consist of a Mariotte bottle, plastic tubing, and a graduated scale. This low-cost gauge design is based on applying the principle of Boyle’s law for gases, which makes it particularly well-suited for the measurement of soil–water characteristics of coarse-grained soils, which desaturate at a faster rate, particularly in the low matric suction range of 0–10 kPa. Among its many uses, this precise gauge is best employed in the axis translation technique to measure matric suction in the range of 0–700 kPa.