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Application of digital image correlation to cement paste
* 1, 2 , 2 , 1
1  Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
2  Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark- Zwijnaarde 904, B-9052

Abstract:

In this paper digital image correlation (DIC) has been applied to study the deformation process of cementitious material at very early age. After mixing of cement-based materials, the cement hydration process begins. Consequently, the ongoing chemical reactions result in a 3D deformation process (shrinkage). The mechanism affecting the very early age hydration as well as specifically the deformation behavior of cementitious materials is a challenging topic. In view of that, it is essential to determine the significant effect of concrete hardening process on the deformation progression at different stages. The technique of DIC is highly sensitive and allows for the first time in literature an accurate and non-contact optical monitoring of the shrinkage of fresh cementitious material. The displacement of the surface is measured by correlating the different digital images taken at different ages after mixing of the material. The system enables a 3D observation that allows a deeper understanding of the deformation progression. The surface displacement determined by DIC-software is compared to the displacement measured by LVDT sensors for calibration purposes. DIC system realizes a more precise method avoiding the effect of self-weight of the traditional sensor. The purpose of this work is to check the sensitivity as well as the effectiveness of DIC technique, to characterize and better understand the 3D deformation process of fresh cementitious materials.

Keywords: Digital image correlation; nondestructive technique; cement-based materials.
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