Sorption isotherm measurements for porous materials: A new hygroscopic method

Abstract

The water sorption of materials can significantly affect their durability. While a wide range of techniques has been already introduced and implemented to measure the sorption behavior of materials, obtaining high-resolution data to describe the water sorption isotherm is still a challenging task. This is especially the case for materials with a complex sorption behavior such as concrete for which the pore structure is very complicated. The level of complexity increases when chloride is present in such structures. In this study, a hygroscopic technique is introduced to measure the sorption behavior of porous materials. By this technique, the sorption isotherm can be obtained by injecting water with a high level of control into a controlled environment where a sample is positioned. The amount of water can be added in steps resulting in high-resolution data for the sorption properties of the sample. The technique is evaluated for two porous materials: Portland cement mortar and sand-lime brick. The results are extensively compared with similar measured data available in the literature. In addition, the performance of the technique is evaluated for porous materials with initial chloride content. The results show that the present technique allows for obtaining high-resolution data in desirable ranges that is essential for materials with complicated pore structures.