My research concerns cementitious systems where part of the traditional Portland cement has been replaced by supplementary cementitious materials to decrease the ecological footprint. More specifically, I study the systems microstructure, moisture- and drying properties. The experimental work includes a number of establish methods, e.g.: isothermal calorimetry, thermogravimetric analysis, sorption balance and the cup method. Aside from increased knowledge about modern cement and concrete, the project can provide material data for future dimensioning tools and durability models.