Abstract
The composition and structure of Calcium-Silicate-Hydrate (C-S-H) phases depends on various reaction parameters leading to its formation. Molecular Dynamic simulation studies probing the formation and structure of C-S-H are generally computationally expensive and can reach only very short time scales. Herein, we propose a coarse graining approach to model the formation of C-S-H, using patchy particles and a modified Patchy Brownian Cluster Dynamics algorithm. The simulations show that patchy particle systems can recover the qualitative kinetic evolution of C-S-H formation, and the obtained final structures were comparable to previously reported molecular dynamics studies and experiments. The model was extended to study the effect of water in the polymerization of tetraethoxysilane oligomers, the principal component of an impregnation treatment for deteriorated concrete surfaces. The intermediate system properties predicted by the simulations, such as viscosity and gel time, and structure were found to be well in accordance with the tailored experiments.
Highlights
Concrete and Portland cement based materials are, the most commonly employed building materials for structural elements, façades, pavements, etc., since the late XIX century
The simulations show that patchy particle systems can recover the qualitative kinetic evolution of C-S-H formation, and the obtained final structures were comparable to previously reported molecular dynamics studies and experiments
The structure of CS-H gel has been a subject of investigation over the last few decades and has produced great advancements employing experimental tools such as NMR, microscopy etc. and simulation studies [5], which we briefly explore in this work
Summary
Concrete and Portland cement based materials are, the most commonly employed building materials for structural elements, façades, pavements, etc., since the late XIX century. Alkoxysilane based consolidation treatments have been used for rehabilitating deteriorated concrete sur faces due to their higher penetration capability and chemical compati bility with cementitious materials [34,35] They polymerize spontaneously producing amorphous SiO2 gels, which is composition ally similar to the siliceous aggregates, and their reticulation degrees and rigidity depends on the initial sol composition [36,37]. In the presence of cementitious matrix, they can produce C-S-H gel [38,39] or even incorporate into the already existing C-S-H phase [33], making them an ideal choice for rehabilitation purposes These impregnation treatments are highly influenced by the reaction conditions such as concrete type, state of decay, sol composition, Ca/Si ratios, water availability, reaction time/rate etc., which determine the mechanical properties and the overall effectiveness and durability of the treatment [40]. Evolution of interme diate system compositions predicted by the simulations were found to be in good agreement with the experiments
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