Browsing by Keyword "Calcium-silicate-hydrate (C-S-H)"
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Item Effect of ternary cements containing thermally activated paper sludge and fly ash on the texture of C-S-H gel(2012-05) Goñi, S.; Frias, M.; Vegas, I.; García, R.; Vigil De La Villa, R.; GENERALThe texture of the C-S-H gels formed in ternary cement blends containing thermally activated paper sludge (APS), fly ash (FA) from coal combustion and Ordinary Portland Cement (OPC) was studied by means of the specific surface area (SSA) and pore-size distribution (PSD), which were measured by the sorption isotherms of nitrogen gas and the BET method. Two differentiated zones in the PSD of the C-S-H gel at ∼10-20 nm and ∼5 nm were observed. The proportion of such zones depends on the age of hydration and amount of OPC replacement. The incorporation of the additions (APS and FA) clearly revealed an increase in both porosity and SSA. This effect decreased with the progress of hydration together with a refinement of the nano-porous structure of C-S-H. High correlations were found among these nanostructure characteristics of the C-S-H gel and mechanical strengths.Item Elastic properties of the main species present in Portland cement pastes(2009-03) Manzano, H.; Dolado, J. S.; Ayuela, A.; Tecnalia Research & InnovationThe elastic properties of the most important phases present in cement pastes have been studied by force field atomistic methods. Calculations reproduce the mechanical properties of crystalline species alite, belite and portlandite fairly well. The elastic properties of amorphous calcium-silicate-hydrate (C-S-H) gel are also explained in terms of the commonly used structural models 1.4 nm tobermorite and jennite, once the intrinsic porosity and the silicate chain length are concurrently considered through the appropriate micromechanical models. The findings conclude that bringing the atomic structure into contact with the mechanical properties of C-S-H gel may modify the actual view of the gel.Item A patchy particle model for C-S-H formation(2022-02) Prabhu, Achutha; Dolado, Jorge S.; Koenders, Eddie A.B.; Zarzuela, Rafael; Mosquera, María J.; Garcia-Lodeiro, Ines; Blanco-Varela, María Teresa; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNThe 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.Item Quantitative correlations among textural characteristics of C-S-H gel and mechanical properties: Case of ternary Portland cements containing activated paper sludge and fly ash(2012-09) Goñi, S.; Frias, M.; Vegas, I.; García, R.; De La Villa, R. Vigil; GENERALThe hydraulic activity of ternary Portland cements containing different proportions of commercial thermally activated paper sludge (APS(I)) and fly ash (FA) from coal combustion was evaluated from the textural characterization of the C-S-H gels formed during hydration. The study was accomplished by means of the specific surface area (SSA) and pore-size distribution (PSD), which were measured by the sorption isotherms of nitrogen gas and the BET method. The microstructure was characterized by scanning electron microscopy (SEM). The incorporation of such admixtures (APS and FA) clearly revealed an increase in both porosity and SSA. This effect decreased with the progress of hydration, together with a refinement of the nano-porous structure of C-S-H. In addition, high correlations were found between nano-structural characteristics of the C-S-H gel and mechanical compressive strengths.