Digital image correlation to characterize the flexural behavior of lightweight ferrocement slab panels

Digital image correlation (DIC) is a relatively new technique for measuring whole-field displacements and strains. In this study, the DIC technique was used to characterize the flexural behavior of ferrocement slab panels containing expanded perlite lightweight aggregate (LWA). Specifically, 12 slab panels containing different number of expanded rib lath layers (1, 2, and 3) and different amount of expanded perlite LWA (55, 35, 15, and 0 vol%) were produced and subjected to three-point loading flexural test. Then the load-deflection curves obtained from displacement sensors were used to verify the DIC results. Afterward, the DIC results were used to evaluate the cracking behavior of all specimens. Scanning electron microscopy (SEM) imaging along with energy dispersive spectroscopy (EDS) analysis was also performed to characterize the microstructure of the mortar of various mixture designs. As expected, the DIC results are in close agreement with those obtained from displacement sensors. The DIC results indicate that the flexural behavior of lightweight ferrocement slab panels is influenced by the number of expanded rib lath layers. The DIC results also show that, although the load bearing capacity of the slab panels were enhanced by increasing the number of expanded rib lath layers, the specimens containing two layers of expanded rib lath has the smallest crack width. The results of the SEM imaging indicate that the increased amount of expanded perlite LWA has resulted in increased porosity (95-380%) and thus decreased density (18-37%) of the lightweight ferrocement mortar.