@article {525, title = {A reaction model for cement solidification: Evolving the C{\textendash}S{\textendash}H packing density at the micrometer-scale}, journal = {Journal of the Mechanics and Physics of Solids}, volume = {118}, year = {2018}, month = {Sep-2018}, pages = {58 - 73}, abstract = {

Cement paste is a multiphase material of complex chemistry, of which 60\% by volume is typically composed of calcium\–silicate\–hydrates (C\–S\–H), the phase that lends the material its strength and stiffness. Moreover, it has been shown that the C\–S\–H phase is a dispersion of nanometer-sized particles that are characterized by an attractive\–repulsive potential and densify in course of the hydration reaction. Herein, we model the nucleation and growth of the nanoparticles as a continuous density field subject to a reaction equation. Using this phase-field approach, we aim to reduce the parameter space present in similar hydration models and create a vehicle to upscale mechanical information from the nanometer-scale to the micrometer-scale. Despite the apparent simplification of the physics at play, we readily reproduce the cement paste reaction kinetics and microtexture\—functions of temperature, coarseness of the calcium\–silicate source particles, and initial water-to-cement ratio\—, and vet them against experimental observations. Presenting results for two-dimensional simulations, we achieve excellent agreement with measurements of hydration heat curves, pore-chord-length and solid-chord-length density functions, distributions of low- and high-density C\–S\–H products, and elasticity.

 Illustration of the dissolution and nucleation and growth processes driving{\textellipsis}

 A comparison between the mean coordination number ⟨z⟩ of the particles modeled{\textellipsis}

 Gibb{\textquoteright}s free energy that interpolates between the source phase ψ=1 and open pore{\textellipsis}

 Gibb{\textquoteright}s energy of reaction and (b) reaction rate for nanoparticle{\textellipsis}

 Evolution of the mean packing fraction of C{\textendash}S{\textendash}H (〈ϕ〉V'; opaque) and the{\textellipsis}

 Diagram of the volume fractions of hydrating cement paste

}, issn = {00225096}, doi = {10.1016/j.jmps.2018.05.010}, url = {https://www-sciencedirect-com.libproxy.mit.edu/science/article/pii/S0022509617308876}, author = {Petersen, Thomas and Valdenaire, Pierre-Louis and Roland Jean-Marc Pellenq and Franz-Josef Ulm} }