Highlighting the role of heterogeneity on the indentation hardness of foamed gypsum

The objective of this work is to link microstructure features of foamed gypsum (lightweight gypsum board core material) and its compressive properties. Several samples of foamed gypsum with different microstructures were manufactured and characterized by X-ray tomography and 3D image processing. Spherical indentation tests results show that for a similar density, the size distribution of the macropores and the distribution of the three levels of porosity has only a very small influence on the mechanical properties. In contrast, the density and homogeneity of spatial distribution of macropores has a much stronger impact on hardness.