A Method for Determination of Absorption Isotherms at High Relative Humidity Levels: Measurements on Lime-Silica Brick and Norway Spruce (Picea abies (L.) Karst.)

ABSTRACT

The relationship between the relative humidity and the moisture content of a material (for relative humidity levels close to 100%) can be studied using the pressure plate technique. However, this method is designed for desorption experiments and modifications are necessary in order to perform absorption experiments. This article presents a method to condition samples to a uniform moisture content by absorption with the pressure plate technique. The specimens were suspended in magnetic clamps until the ceramic plate had equilibrated with the applied pressure and modifications were made so that water could circulate through the pressure plate cell.

KEYWORDS:

• Hysteresis
• method development
• pressure plate
• sorption isotherm
• suction curve