The chemical and mineral composition, physical and mechanical properties, and pozzolanic activity of ancient bricks from Hubei Province, China were investigated in this study. X-ray diffraction (XRD), thermogravimetric analysis (TG-DSC), X-ray fluorescence analysis (XRF) and scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) were adopted to characterize the chemical composition, crystalline minerals and microstructure of the ancient bricks. The results show that quartz is the dominant component in most ancient bricks, with a content exceeding 70% in samples BB-2, BB-5, BB-6 and BB-7. Some bricks contain minor non-clay minerals such as calcite, dolomite and albite. On some points in the SEM image, substances such as gypsum, calcite, and quartz can be clearly seen. The calcining temperature of the ancient bricks from Yupan Village, Xiantao City (sample BB-1), does not exceed 600 °C, while that of other samples ranges from 800 to 1100 °C. The compressive strength of most ancient bricks is around 10 MPa, with the highest value of 14.3 MPa (BB-6) and the lowest of 1.2 MPa (BB-3). The apparent density of all samples is approximately 2.2 g/cm3, and the water absorption rate ranges from 6.5% to 23.1%. The pozzolanic activity index of some samples reaches 76% at 28 days, with the 150-year-old sample BB-7 showing the best activity. This study provides a reliable experimental basis for analyzing the weathering resistance and deterioration mechanism of ancient bricks in Hubei Province, offers technical support for the restoration of local ancient buildings, and lays a foundation for the development of antique-style brick craftsmanship.
Wu et al. (Wed,) studied this question.