Mechanisms of Phase Transformation and Creating Mechanical Strength in a Sustainable Calcium Carbonate Cement
Jesús Rodríguez-Sánchez,
Teresa Liberto,
Catherine Barentin,
Dag Kristian Dysthe
Affiliations
Jesús Rodríguez-Sánchez
Physics of Geological Processes (PGP), The NJORD Centre, Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway
Teresa Liberto
Building Physics and Construction Ecology, Faculty of Civil Engineering, Institute of Materials Technology, Vienna University of Technology, 1030 Vienna, Austria
Catherine Barentin
Institut Lumière Matière, Université Claude Bernard Lyon 1, CNRS, F-69622 Villeurbanne, France
Dag Kristian Dysthe
Physics of Geological Processes (PGP), The NJORD Centre, Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway
Calcium carbonate cements have been synthesized by mixing amorphous calcium carbonate and vaterite powders with water to form a cement paste and study how mechanical strength is created during the setting reaction. In-situ X-ray diffraction (XRD) was used to monitor the transformation of amorphous calcium carbonate (ACC) and vaterite phases into calcite and a rotational rheometer was used to monitor the strength evolution. There are two characteristic timescales of the strengthening of the cement paste. The short timescale of the order 1 h is controlled by smoothening of the vaterite grains, allowing closer and therefore adhesive contacts between the grains. The long timescale of the order 10–50 h is controlled by the phase transformation of vaterite into calcite. This transformation is, unlike in previous studies using stirred reactors, found to be mainly controlled by diffusion in the liquid phase. The evolution of shear strength with solid volume fraction is best explained by a fractal model of the paste structure.
