Three-dimensional computer modeling of slag cement hydration

Abstract

A newly developed version of a three-dimensional computer model for simulating the hydration and microstructure development of slag cement pastes is presented in this study. It is based on a 3-D computer model for Portland cement hydration (CEMHYD3D) which was originally developed at NIST, taken over in the authors' group and further developed. Features like the digitized 3-D microstructure, the cellular automata (CA) algorithm for simulating the random walking, phase transformation for simulating the chemical reactions, are retained. But, the 3-D microstructure was reconstructed allowing for slag particles as binder in the system. Algorithms and rules are developed to account for the interaction between Portland cement hydration and slag reaction in the paste, of which the mechanisms were revealed in the studies by Chen and Brouwers [(2007) J Mater Sci 42(2):428; (2007) J Mater Sci 42(2):444] Methods for considering the various factors on the reactivity of slag in hydrating slag cement pastes are proposed, mainly for the oxide composition of slag and the alkalinity in the pore solution composition. A comparison between the model predictions and the experimental results in literature shows that the presented computer model can successfully predict the hydration process and the microstructure development of hydrating slag cement paste.

Analysis of Hydration-Mechanical-Durability Properties of Metakaolin Blended Concrete

“…Similarly, Chen et al [23] also found that at the same curing age, the finer slag had a higher reaction degree than the coarser slag. Appl Figure 4 shows the parameter studies on the degree of binder reaction in the MK blended concrete.…”

“…Similarly, Chen et al [23] also found that at the same curing age, the finer slag had a higher reaction degree than the coarser slag. …”

“…This was because of the increase in available depositing space for the high water to binder ratios mix. Similarly, Lam et al [22] and Chen et al [23] also found that for fly ash or slag composite binders, the reaction degree of mineral admixture increased when the water to binder ratio increased or the mineral admixture placement level decreased.…”

Comparison of observed and simulated cement microstructure using spatial correlation functions

“…This model is primarily based on CEMHYD3D version 1.0 that was developed at NIST [3]. The UT model is modified from the original CEMHYD3D that simulates the processes of cement hydration and the formation of microstructure [18]. The UT version is an extension and can for instance simulate diffusion-controlled processes during cement hydration and minimize the influence of system resolution on the model predictions.…”

“…A time conversion factor is used to relate the hydration cycles to real time. It is proven that the new CEMHYD3D UT version is robust in regard to the time conversion factor, indicating that most of the important kinetic factors of the cement hydration process are successfully considered in the computer model [18,19].…”