Materials Characterization of Historical Structures: A Review

Newswise — In the field of cultural heritage preservation, historical structures serve as crucial links to humanity’s art, architecture, history, and culture. Their long-term survival and transmission to future generations depend heavily on understanding the properties of their building materials—such as natural stones (limestone, basalt, granite, etc.) and mortars (lime-based, Khorasan, Adobe, etc.)—and selecting appropriate restoration materials. However, challenges persist, including limited holistic analysis of material properties and a lack of clear guidance for choosing characterization methods, which hinder scientific restoration and conservation efforts.

Therefore, a research team from the Department of Civil Engineering at Çanakkale Onsekiz Mart University, Türkiye, conducted a review study titled “Materials characterization of historical structures: A review” to address these gaps.

This study comprehensively evaluates analytical methods for characterizing historical building materials, synthesizes existing research findings, and clarifies the strengths and limitations of each technique to guide researchers in methodology selection. The research systematically reviews key aspects including the objectives of material property-determination methods, sampling and sample preparation processes, characteristics of testing equipment, and analysis results. It focuses on four core categories of characterization techniques:

1. Physical and thermal property analysis: Mercury Intrusion Porosimetry (MIP) is used to determine porosity, pore structure, and water permeability (e.g., identifying two main pore size distributions—0.01–1 μm and 1–10 μm—in mortars from Amaiur Castle). Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) assess thermal resistance and mass loss behavior (e.g., calcite decomposes at 600–900 °C with 20%–40% mass loss due to CO₂ emission).
2. Chemical property analysis: Techniques such as X-ray Diffraction (XRD) (for mineral composition, e.g., calcite and quartz as main minerals in most mortars), X-ray Fluorescence (XRF) (for elemental content like SiO₂ and CaO), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectrometry, Nuclear Magnetic Resonance (NMR), and Inductively Coupled Plasma (ICP) analysis (for heavy metal detection, e.g., high Pb and Zn concentrations in Seville Cathedral’s black crusts) are employed to qualitatively and quantitatively determine material components.
3. Mechanical property analysis: Non-destructive or semi-destructive methods including Ultrasonic Pulse Velocity (UPV) (correlating wave speed with concrete quality), Schmidt hammer (measuring surface hardness to estimate compressive strength), and Flat-jack tests (assessing in-situ stress and Young’s modulus) are used to avoid damaging historical structures while evaluating their mechanical performance.
4. Visualization techniques: Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) (for microstructural and elemental distribution analysis), Optical Microscopy (OM) (for mineral observation under polarized light), and Infrared Thermography (IRT) (for detecting moisture and cracks, e.g., identifying invisible cracks in Malatya Taşhoran Church) help visualize material morphology and hidden defects.

Extensive reviews of studies on benchmarks (e.g., Roman-period structures in Portugal, 11th–14th century buildings in Spain, and Mamluk-period structures in Egypt) validate the effectiveness of these techniques. The combined use of multiple methods yields more consistent and reliable results, providing a data-driven foundation for future scientific research, cost reduction in engineering and architectural analysis of historical structures, and support for the development of scientifically grounded restoration projects.

The paper “Materials characterization of historical structures: A review” is authored by Mertcan DEMIREL, Alican TOPSAKAL, and Muhammet Gökhan ALTUN (corresponding author). Full text: https://doi.org/10.1007/s11709-025-1222-3.