Fiber Reinforced Concrete Crack Opening Evaluation Using Digital Image Correlation Techniques

The analysis of mechanical properties in fiber reinforced concrete (FRC) elements is basically done through destructive tests since the results obtained by these methods are already well established in normative codes. One of them is the 3-point flexural test normalized by EN 14651 using a notched beam to measure the crack width (CMOD). Within the context of the mechanical properties evaluation that do not require the production or extraction of specimens, and can be applied in fully functioning structures, the digital image correlation (DIC) is a technique which has been proposed. This non-destructive test analyzes a group of images correlating one with each other, evaluating the changes that occurred during the load has been applied. It is a non-invasive test, capable of results with acceptable precision and a considerable low cost, proving to be a promising technique in the field of behavior analysis. Thus, this study compares the cracking results obtained through the extensometry technique (Linear Variable Differential Transformer – LVDT) and the digital image correlation. The samples were made using steel fibers. The results obtained using the DIC technique were validated by the data obtained through the LVDTs, and the absolute error was considerably low.