Mineralogical and microstructural characterization of ceramics from the fifth and fourth millennium BC in the central plateau of Iran

This research presents the effects of sintering process and clay composition on the physico-mechanical properties of ceramics from the fifth and fourth millennium BC (6950 ± 280 to 5040 ± 220 TL dating). The combined multiscale mercury intrusion porosimetry (MIP) revealed the increase of round cryptopores and ultramicropores in a range of 0.01–0.1 μm and 0.1–5 μm respectively, closely linked to vitrified glassy connections and bonding between particles and the partial melting of phyllosilicates with different sizes of bubbles at 950 °C. Cold crushing strength (CCS) of the ceramics, containing high calcite and phyllosilicate mineral exhibited a lower strength value from 6.24 to 6.31 MPa at ∼750–800 °C due to the increase in crack porosity area with high interconnectivity and internal stresses. However, the ceramics with a well glassy network show a higher strength value of 16.5Mpa, contributing to sustainable ceramic materials with a uniform cross-section >900 °C and minimal shrinkage for conservation treatment.