Anders Anderberg

An improved method to validate the relative humidity generation in sorption balances.

Sorption balances are instruments in which samples are weighed as they are exposed to a programmed relative humidity (RH). Such instruments are used to measure sorption isotherms and to study solid-vapour interaction. There are different methods to validate the performance of the RH generation in such instruments by charging them with saturated salt solutions and ramping/stepping the RH past the deliquescence RH of the salts. In this paper, an improved approach to perform validation is presented, where the RH is kept stepwise constant at a quasi-randomly chosen set of RH-values above and below the deliquescence RH. From the rates of change of mass as a function of RH, it is possible to calculate the RH at which deliquescence takes place. This alternative method gives similar results as the slow ramp method, but it is less sensitive to disturbances and is less time consuming.

Drying and hydration of cement based self-leveling flooring compounds

Water in building materials not only influences important physical properties and chemical processes but is also related to the well-being of the occupants of a building. The drying of cementitious materials is complex, involving several different drying processes. The conditions for each drying process change as the material changes its properties as it goes from a particle suspension in the fresh state to a fine porous material in the hardened state. The present article describes and quantifies the drying processes of cement-based self-leveling flooring compounds (SLCs) and relates them to the extent of reaction, which here is quantified by isothermal calorimetry. The relative importance of the different drying processes is discussed and a model for the drying of the SLCs is proposed.