Investigating morphological changes in treated vs. untreated stone building materials by x-ray micro-CT

Area of Science:

• Geosciences
• Materials Science
• Conservation Science

Background:

• Calcareous stones, particularly calcarenites, are vital in historical architecture but susceptible to weathering due to high calcite content and porosity.
• Protective polymer treatments are essential for mitigating deterioration in historic stone structures.

Purpose of the Study:

• To investigate the morphological changes in biocalcarenite (Lecce stone) after conservation treatments using micro-X-ray computed tomography (micro-CT).
• To quantitatively assess the impact of Paraloid B72 (PB 72) and a fluoroelastomer (NH) on stone porosity and internal structure.

Main Methods:

• Micro-X-ray computed tomography (micro-CT) was employed to analyze the internal structure of Lecce stone samples.
• Porosity and morphological parameters were calculated before and after treatment.
• Student's t-test was used for statistical comparison of results.

Main Results:

• Paraloid B72 (PB 72) demonstrated homogenous distribution and caused minimal alterations to the stone's natural properties.
• The fluoroelastomer (NH) treatment resulted in a significant decrease in porosity.
• NH treatment led to variations in wall thickness distribution, likely due to inhomogeneous application.

Conclusions:

• Paraloid B72 (PB 72) is a suitable conservation agent for Lecce stone, preserving its natural characteristics.
• The fluoroelastomer (NH) effectively reduces porosity but may induce undesirable structural changes in the stone.