Scherer – Hydration and Percolation
Gary P. Funkhouser, Sulapha Peethamparan, Emily Weissinger, Jie Zhang, and George Scherer
Princeton University
Setting of cement paste is thought to occur when the layer of hydration products on the particles becomes thick enough to allow percolation. This physical situation is captured by the Cherry Pit model developed by Torquato and coworkers, which describes the percolation of spheres with impenetrable cores (representing the unhydrated cement) and penetrable shells (representing the hydration products). The advantage of this model is that it provides a prediction of the amount of hydration required to produce percolation as a function of the initial solids content (i.e., water/cement ratio). We have characterized hydration and setting by using a combination of chemical shrinkage, TGA, Vicat testing, and acoustic methods. The results will be interpreted in terms of the Cherry Pit model.