Using digital image correlation to evaluate plastic shrinkage cracking in cement-based materials

Fresh concrete exposed to a drying environment is susceptible to plastic shrinkage cracking, which can result in negative impacts on concrete durability. In the current ASTM standard, plastic shrinkage cracking is evaluated by the average crack width measured at 24 h after concrete placement, considering that the traditional crack measurement tools cannot be used on fresh concrete. In this work, a non-contact strain measurement technique based on digital image correlation (DIC) was applied to study the behavior of plastic shrinkage cracking. The crack areas were also determined by image analysis using MATLAB functions. It was found that DIC can provide a series of strain contour maps that help to understand the process of plastic shrinkage cracking. The effects of air temperature, w/c, and substrate roughness were well explained by both DIC analysis results and crack areas computed in MATLAB.