Time-dependent load-induced deformation of Ca(OH)₂

Short-term time-dependent strains were monitored on calcium hydroxide compacts having a porosity of 19·7%. The creep experiments were conducted in a controlled environment chamber maintained dry (0% RH) at 22 ± 2°C with nitrogen purging. Prior to loading, the compact specimens were vacuum dried at 105°C for 3 h (equivalent to D-drying). The applied stress for the creep test corresponds to 5% of the compaction pressure (386 MPa). The Ca(OH)₂ compact specimens were in the form of T-shaped columns with a minimum thickness value (for the web and flanges) less than 1·2 mm. The AC impedance spectra of loaded and unloaded Ca(OH)₂ compact specimens were also monitored in real time. This was achieved by the coupling of the impedance analyser to the creep experiment. An assessment of the relevance of the high frequency arc depression angle obtained from the impedance analysis to an understanding of the load-induced deformation behaviour of the Ca(OH)₂ compacts was made.