In the preservation of cultural heritage, restoration is not merely a physical intervention; it is a data-driven, ethically controlled, and continuous system management. Modern conservation approaches restoration in three interconnected phases: documentation, implementation, and monitoring.
This cyclical approach guarantees both the technical accuracy of the intervention and the preservation of historical authenticity.
Keywords: Restoration cycle, ICOMOS principles, non-destructive testing, building health monitoring, recyclability, cultural heritage.
1. Documentation: Project Preparation and Diagnostic Data Set
Documentation is the “diagnostic” phase of restoration. According to ICOMOS principles, recording the unaltered original state ensures the ethical legitimacy of the project.
1.1 Non-Destructive Testing and Current Condition Analysis
Modern documentation is like taking an "x-ray" of a structure:
- Photogrammetry and Laser Scanning: Creating a millimeter-accurate 3D digital twin of the structure.
- Deterioration Analysis: Creation of moisture maps using thermal cameras and identification of voids within the material using ultrasonic tests.
- Laboratory Data: Determination of the chemical composition of the existing mortar and stone through SEM-EDX and XRD analyses.
Documentation is the “black box” of restoration; every mistake or success made during the process can be analyzed thanks to these initial records.
1.2 Planning the Intervention Strategy
At this stage, minimum intervention criteria are determined, material selections are designed, and risks are identified in advance by integrating field and laboratory data. The documentation process minimizes the risks associated with misdiagnosis and strengthens the ethical foundation of the project.
2. Application: Transforming Scientific Data into Practice
The implementation phase involves comparing the data obtained during the documentation phase with laboratory tests in the field.
2.1 The "Three Golden Rules" in Material Selection
Each new material used during the application is selected according to the following criteria:
- Physical Compatibility: The compressive strength of the new mortar should not be higher than that of the original mortar; otherwise, it may crack the historical material.
- Chemical Compatibility: To avoid sulfate-containing cement-based materials, binders such as natural hydraulic lime (NHL) are preferred.
- Reversibility: The reinforcing material used should be removable from the structure when a more advanced technology becomes available in the future.
This step ensures a technically and ethically safe intervention by preventing material incompatibility.
3. Monitoring: Long-Term Performance and Sustainability
Restoration doesn't end when the scaffolding is dismantled. Monitoring is a tangible application of ICCROM's sustainability vision. This phase assesses the long-term effectiveness of the intervention and provides preventative protection against unforeseen problems.
3.1 Structural Health Monitoring
- Sensor Technologies: Real-time data collection through "crack-meters" placed in cracks or humidity/temperature sensors embedded in the structure.
- Periodic Inspection: Visual and technical inspection of the treated areas at 6-month, 1-year, and 5-year intervals.
- Data Feedback: Minor deteriorations detected during monitoring are transformed into preventative conservation interventions that avoid large restoration costs.
4. Advantages of the Circular Approach
The documentation phase forms the basis of the intervention, ensuring the preservation of historical authenticity and preventing the risk of misdiagnosis. The implementation phase guarantees the correct application of technical and ethical interventions, eliminating the risk of material incompatibility. The monitoring phase ensures the sustainability of the intervention and prevents intervention failure by identifying potential problems early.