Implementação de modelo matemático de nucleação e crescimento e simulação da hidratação de cimento Portland

Abstract

The hydration of Portland cement is considered a complex reaction due to the number of variables involved and processes for complete hydration. Some questions about the mechanisms that control the cement hydration phenomenon - especially at early ages - are questionable and responses based on experimental procedures and theoretical models remain unclear. In order to analyze the mathematical formulation of the BNG model (Boundary Nucleation and Growth), were performed implementation and simulations with meaningful parameters based input on recent data of literature for different stoichiometric values of water and cement (factor w/c), nucleation rates, rise of hypothesis nuclei and growth anisotropy. The HYDAC software developed in this work was used in computer simulations to obtain hydrated volume fraction values and chemical shrinkage. The results for the output variables have been analyzed from the numeric perspective and kinetic according to the used iterations of input parameters. Analysis of these results indicates that numeric responses hydration and retraction are consistent with the use of parameter variations, and are directly related to each nucleation rate, the number of nuclei, the factor w/c and the values of transformed volume fraction and volumetric variation. Furthermore, the simulation results with a variation of anisotropy parameters indicate low sensitivity model for the proposed range of simulated values.