Tricalcium Silicate Hydration with CaCl2: Application of the Boundary Nucleation Model to Quasielastic Neutron Scattering Data

摘要

Tricalcium silicate (C3S) hydration in the presence of CaCl2 is followed using quasielastic neutron scattering (QENS) and the kinetics of product nucleation and growth are modelled using a boundary nucleation (BN) model combined with a diffusion-limited hydration model. The BN model, previously applied to calorimetry data of hydrating C3S/CaCl2, is applied to QENS data that includes components whose time-evolution does not follow that for evolved heat (measured using calorimetry). This work tests the BN model to describe QENS data for C3S/CaCl2 and compares the results with those previously published for the BN model using calorimetry. Notably, we find large differences in the specific nucleation rate obtained from the BN model using QENS and calorimetry data. The BN model produces comparable quality fits to those from the commonly-used JohnsonCMehlCAvramiCKologoromov (JMAK) model for QENS data of C3S paste and a better fit to data for the C3S/CaCl2 paste. The BN model is found to support the theory that nucleation and growth begins at the time of mixing and proceeds with a single kinetic process. The differences in the calorimetry and QENS data revealed using the BN model are not reflected in the JMAK model, where good agreement is found between the nucleation and growth rate obtained from QENS and calorimetry data. The differences found using the BN model between QENS and the calorimetry data are attributed to differences in C3S samples rather than the experimental analysis technique. Further work is required to definitively establish this.