Time-Lapse GPR Measurements to Monitor Resin Injection in Fractures of Marble Blocks.

Area of Science:

• Geophysics
• Materials Science
• Conservation Science

Background:

• Marble repair operations often use epoxy resin injections to fill fractures.
• Quality control of these injections is crucial for structural integrity and material preservation.
• Traditional methods may not accurately assess the effectiveness of resin penetration.

Purpose of the Study:

• To evaluate the feasibility of time-lapse ground-penetrating radar (GPR) for quality control of marble repair injections.
• To assess GPR's ability to monitor epoxy resin filling in simulated and natural marble fractures.
• To compare GPR results with theoretical predictions and validate its accuracy.

Main Methods:

• Laboratory experiments using Carrara marble blocks with simulated air-filled fractures.
• Application of 3 GHz GPR before and after epoxy resin injections.
• Comparison of GPR amplitude reduction with thin bed theory predictions.
• Field testing on a naturally fractured marble block.

Main Results:

• Time-lapse GPR measurements accurately detected amplitude reductions caused by resin substitution of air.
• GPR successfully distinguished between unfilled, partially filled, and totally filled fractures.
• An automatic algorithm was developed for quantitative analysis of GPR data.
• Both lab and field tests confirmed GPR's effectiveness, pending proper equipment calibration.

Conclusions:

• Time-lapse GPR is a viable and accurate tool for quality control of resin injections in marble.
• The developed method can improve repair effectiveness and reduce natural stone waste.
• The procedure is ready for implementation in the marble industry.