Digital image correlation (DIC) on fresh cement mortar to quantify settlement and shrinkage

The displacement of fresh cementitious media initiated by water evaporation and cement hydration is very complex. In the plastic state, the cement particles deform in the plane and move at different rates leading to the development of plastic shrinkage cracks. In parallel, the material settles as bleed water is released. Tracking the particles three-dimensional heterogeneous displacement requires a highly-sensitive monitoring technique. Digital image correlation (DIC) has been selected to quantify settlement and shrinkage strain evolution. DIC excels compared to classical LVDT point-transducers since it is non-contact and the analysis is full field providing a three-dimensional (3D) view of deformations and strains. 3D visualization maps of early-age deformation contribute to the interpretation of early age mobility. DIC enables the measurement of non-uniform surface displacement due to material heterogeneity and geometry that affects the shrinkage distribution which cannot be detected by traditional LVDTs. The procedure through which the DIC speckle pattern is applied on a wet rough surface is critically discussed. (C) 2018 Politechnika Wroclawska. Published by Elsevier B.V. All rights reserved.