Hysteretic effects ofmoisture storage of calcium silicate insulation boards

Significance of hysteretic effects on hygroscopic moisture storage of calcium silicate insulation boards (CS)is investigated. The water vapour adsorption, desorption and scanning curves of CS were measured in relative humidity (RH) range from 0 to 98% by the standard desiccator method, consisting in conditioning the samples in desiccators under constant RH and temperature (23 degrees C). The hygric performance of CS specimen under dynamic conditions-cyclic changing RH and constant temperature was tested in a climatic chamber with precise control of temperature and relative humidity. The test was performed with 24/48 hours step changes between 53 and 81% of RH. The moisture uptake and release during the dynamic test was determined by a continuous weighing of the specimen. The results of the dynamic test are compared with numerical simulation, using the steady-state hygric properties. The both static as well as dynamic measurements have shown a presence of hysteretic behaviour. Based on the analysis of the experimental results a significance of hysteretic effects on hygro-thermalperformance of CS in the hygroscopic range is discussed.