Use of Multiphase Voxels to Simulate the Effects of Nano-Silica on Cement Hydration

This study investigated the hydration of nano-silica-incorporated cement paste using multiphase voxels in the developed CEMHYD3D model. Multiphase voxels were firstly proposed to be able to consider the effects of nano particles on cement hydration process in microscale simulation. Multiphase voxels contain two phases in a voxel unlike conventional single-phase voxels used in current CEMHYD3D. Four types of multiphase voxels were developed in this study to consider the effects of adding nano-silica on cement hydration such as multiphase voxels of water and nano-silica (S–H), nano-silica and solid C–S–H (S-CSH), nano-silica and diffusing CH (S-CH*), nano-silica and diffusing C–S–H (S-CSH*). By using proposed multiphase voxels, the effects of nano-silica including nucleation sites and pozzolanic reaction were fully considered in the developed CEMHYD3D model. In addition, dissolution rate equations for four major phases of cement were proposed to simulate the cement hydration based on the number of calcium silicate hydrate. The effects of nano-silica on the heat formation and rate of heat obtained from simulation by using proposed multiphase voxels and dissolution rate equations in the developed model were consistent with those experimentally obtained for four different nano-silica substitutions of 0.0%, 1.5%, 3.0% and 5.0% by weight of binder with a water-to-binder ratio of 0.45. Researchers and construction industry can use the multiphase voxel method to simulate the hydration of cement-based materials containing nano particles in micro level simulation saving significantly computational cost.