Heterogeneity analysis of mortar from different architectural parts: a case study of the sixth-generation Duanyi King’s Tomb of the Ming Dynasty Jingjiang Mausoleum, China

The Jingjiang Princes’ Mausoleum, a representative Ming dynasty royal tomb, features lime mortars that serve both functional and artistic roles in its aboveground architecture. This study examines three mortar types from the gate of the sixth-generation Prince Mausoleum: wall plaster, brick joint mortar, and roof tile joint mortar. Using a combination of polarized light microscopy (PLM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), wet chemical analysis, thermogravimetric–differential scanning calorimetry (TG-DSC), and scanning electron microscopy (SEM), the mineral composition, lime type, raw materials, organic additives, and microstructure were systematically analyzed. The results indicate that all the samples are calcium-based lime mortars, but they exhibit certain differences in their compositional formulations. The red wall plaster exhibits a two-layered structure: the outer layer, enriched with ochre powder, imparts a distinctive red lime finish that emphasizes the architectural hierarchy, whereas the inner lime layer, without the addition of iron-bearing minerals, primarily serves to provide structural support and adhesion. The masonry mortar between the wall bricks was made with relatively pure lime, and no evident aggregates or organic additives were identified.Proteinaceous additives found in the tile joint mortar likely enhance water resistance. These findings demonstrate the technical sophistication of Ming dynasty artisans and reflect the cultural symbolism and construction standards of royal funerary architecture. This research provides valuable insights for understanding Ming mortuary construction technologies and supports conservation efforts of related heritage sites.

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