Study of porous limestone mechanical behavior with digital image correlation: calibration and validation

This article deals with the monitoring of strain on tuffeau, a soft and porous building limestone used in stonework in historical masonry. Previous studies have shown the limitations of using strain gauges for mechanical monitoring, due to the size and local nature of the measurement. The digital image correlation (DIC) technique has proved to be a significant, non-contact and non-destructive method for full-field strain measurements of various materials, including rocks which are natural and therefore heterogeneous. In this work, we studied the DIC parameters and calibration process to identify the best configuration for working with a porous limestone material subjected to mechanical loading. Because of its potential impact on the quality of strain measurement, we also explored the effect of geometry and rectification. While the results provide a set of optimized parameters to get the best out of DIC analysis, they also highlight the importance of rectification on the mechanical behavior of such soft, porous stones.