Fractal nucleation and growth model for the hydration of tricalcium silicate

The phase transformation kinetics of the tricalcium silicate reaction for the period of peak hydration rate can be described as a four-parameter exponential nucleation and growth model. The exponent in the model can take a noninteger value that may be an irrational number. Application of a fractal impingement model based on a mean field diffusion-limited aggregation (DLA) process results in a fractal nucleation and growth model. This indicates consistency between small-angle neutron scattering (microstructural) and quasi-elastic neutron scattering (kinetics) measurements. Also, the fractal basis of the exponent in the kinetics model precludes the interpretation of conventional grain growth processes. Concerning the analysis of kinetics data, the four-parameter form of the kinetics model means that the double logarithmic least squares fit to the kinetics data is not appropriate. Instead, a nonlinear curve fitting approach is necessary. (C) 2001 Elsevier Science Ltd. All rights reserved.