Browsing by Author "Dolado, Jorge S."
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item Effect of addition of silica- and amine functionalized silica-nanoparticles on the microstructure of calcium silicate hydrate (C-S-H) gel(2015-07-05) Monasterio, Manuel; Gaitero, Juan J.; Erkizia, Edurne; Guerrero Bustos, Ana M.; Miccio, Luis A.; Dolado, Jorge S.; Cerveny, Silvina; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNIn this work we study the influence of adding nano-silica (SiO2, Nyasil™) and aminopropyl (-(CH2)3-NH2,) functionalized silica nanoparticles (Stoga) during the synthesis of calcium-silicate-hydrate (C-S-H gel). Characterization by solid state 29Si NMR and ATR-FTIR spectroscopy showed that the addition of both particle types increases the average length of the silicate chains in C-S-H gel being this effect slightly more important in the case of Stoga particles. In addition, 13C NMR and XPS confirmed that the aminopropyl chain remains in the final product cleaved to silicon atoms at the end of the silicate chain of C-S-H gel whereas XRD measurements showed that this result in an increment in the basal distance compared with ordinary CSH. In addition, the dynamics of water within the pores of C-S-H gel was analyzed by broadband dielectric spectroscopy. We observed that water confined in C-S-H formed with the addition of nanoparticles is faster than that in plain C-S-H which can be related to a different porous structure in these materials.Item Effect of chemical environment on the dynamics of water confined in calcium silicate minerals: Natural and synthetic tobermorite(2015-05-05) Monasterio, Manuel; Gaitero, Juan J.; Manzano, Hegoi; Dolado, Jorge S.; Cerveny, Silvina; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNConfined water in the slit mesopores of the mineral tobermorite provides an excellent model system for analyzing the dynamic properties of water confined in cement-like materials. In this work, we use broadband dielectric spectroscopy (BDS) to analyze the dynamic of water entrapped in this crystalline material. Two samples, one natural and one synthetic, were analyzed, and despite their similar structure, the motion of confined water in their zeolitic cavity displays considerably different behavior. The water dynamics splits into two different behaviors depending on the chemical nature of the otherwise identical structural environment: water molecules located in areas where the primary building units are SiO4 relax slowly compared to water molecules located in cavities built with both AlO4 and SiO4. Compared to water confined in regular porous systems, water restricted in tobermorite is slower, indicating that the mesopore structure induces high disorder in the water structure. A comparison with water confined in the C-S-H gel is also discussed in this work. The strong dynamical changes in water due to the presence of aluminum might have important implications in the chemical transport of ions within hydrated calcium silicates, a process that governs the leaching and chemical degradation of cement.Item KIMERA: A Kinetic Montecarlo Code for Mineral Dissolution: A kinetic montecarlo code for mineral dissolution(2020-09-18) Martin, Pablo; Gaitero, Juan J.; Dolado, Jorge S.; Manzano, Hegoi; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNKIMERA is a scientific tool for the study of mineral dissolution. It implements a reversible Kinetic Monte Carlo (KMC) method to study the time evolution of a dissolving system, obtaining the dissolution rate and information about the atomic scale dissolution mechanisms. KIMERA allows to define the dissolution process in multiple ways, using a wide diversity of event types to mimic the dissolution reactions, and define the mineral structure in great detail, including topographic defects, dislocations, and point defects. Therefore, KIMERA ensures to perform numerous studies with great versatility. In addition, it offers a good performance thanks to its parallelization and efficient algorithms within the KMC method. In this manuscript, we present the code features and show some examples of its capabilities. KIMERA is controllable via user commands, it is written in object-oriented C++, and it is distributed as open-source software.Item Mechanisms and Dynamics of Mineral Dissolution: A New Kinetic Monte Carlo Model: A New Kinetic Monte Carlo Model(2019-10-01) Martin, Pablo; Manzano, Hegoi; Dolado, Jorge S.; Tecnalia Research & InnovationMineral dissolution is a fundamental process in geochemistry and materials science. It is controlled by the complex interplay of atomic level mechanisms like adatoms and terraces removal, pit opening, and spontaneous vacancy creation that can be gradually activated at different energies.Item A multi-scale approach for percolation transition and its application to cement setting(2018-10-25) Prabhu, Achutha; Gimel, Jean-Christophe; Ayuela, Andrés; Arrese-Igor, Silvia; Gaitero, J.J.; Dolado, Jorge S.; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNShortly after mixing cement grains with water, a cementitious fluid paste is formed that immediately transforms into a solid form by a phenomenon known as setting. Setting actually corresponds to the percolation of emergent network structures consisting of dissolving cement grains glued together by nanoscale hydration products, mainly calcium-silicate-hydrates. As happens in many percolation phenomena problems, the theoretical identification of the percolation threshold (i.e. the cement setting) is still challenging, since the length scale where percolation becomes apparent (typically the length of the cement grains, microns) is many times larger than the nanoscale hydrates forming the growing spanning network. Up to now, the long-lasting gap of knowledge on the establishment of a seamless handshake between both scales has been an unsurmountable obstacle for the development of a predictive theory of setting. Herein we present a true multi-scale model which concurrently provides information at the scale of cement grains (microns) and at the scale of the nano-hydrates that emerge during cement hydration. A key feature of the model is the recognition of cement setting as an off-lattice bond percolation process between cement grains. Inasmuch as this is so, the macroscopic probability of forming bonds between cement grains can be statistically analysed in smaller local observation windows containing fewer cement grains, where the nucleation and growth of the nano-hydrates can be explicitly described using a kinetic Monte Carlo Nucleation and Growth model. The most striking result of the model is the finding that only a few links (~12%) between cement grains are needed to reach setting. This directly unveils the importance of explicitly including nano-texture on the description of setting and explains why so low amount of nano-hydrates is needed for forming a spanning network. From the simulations, it becomes evident that this low amount is least affected by processing variables like the water-to-cement ratio and the presence of large quantities of nonreactive fillers. These counter-intuitive predictions were verified by ex-professo experiments that we have carried out to check the validity of our model.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 Supercritical hydrothermal flow synthesis of xonotlite nanofibers(2018-06-01) Díez-García, Marta; Gaitero, J.J.; Santos, J.I.; Dolado, Jorge S.; Aymonier, Cyril; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNThis article reports a satisfactory and innovative method for the synthesis of xonotlite using a flow reactor and supercritical water. This study widens the variety of inorganic nanofibers produced in record breaking times by means of continuous reactors working under supercritical water conditions. In particular, the synthesis time of xonotlite, which takes normally more than 5 h, was reduced to only 20s by carrying out the reaction at 400 °C and 23.5 MPa. Resulting product was studied by several characterization techniques: x-ray diffraction, transmission electron microscopy, 29Si and 1H nuclear magnetic resonance and infrared spectroscopy. Furthermore, obtained product consisted of highly pure and crystalline flat nanofibers of 1–10 μm long with a length to diameter ratio of the order of 100. Also, the typical deviation from the ideal structure observed by nuclear magnetic resonance and the presence of Si-OH were explained in terms of surface defects. This work reinforces the interests of using supercritical conditions for the fast synthesis of crystalline nano-calcium silicates which, due to the number of potential industrial applications and the scalability of the technology, might represent technological breakthrough.Item Ultra-Fast Supercritical Hydrothermal Synthesis of Tobermorite under Thermodynamically Metastable Conditions(2017-03-13) Diez-Garcia, Marta; Gaitero, Juan J.; Dolado, Jorge S.; Aymonier, Cyril; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNTobermorite is a fibrillar mineral of the family of calcium silicates. In spite of not being abundant in nature, its structure and properties are reasonably well known because of its interest in the construction industry. Currently, tobermorite is synthesized by hydrothermal methods at mild temperatures. The problem is that such processes are very slow (>5 h) and temperature cannot be increased to speed them up because tobermorite is metastable over 130 °C. Furthermore the product obtained is generally foil-like and not very crystalline. Herein we propose an alternative synthesis method based on the use of a continuous flow reactor and supercritical water. In spite of the high temperature, the transformation of tobermorite to more stable phases can be prevented by accurately controlling the reaction time. As a result, highly crystalline fibrillar tobermorite can be obtained in just a few seconds under thermodynamically metastable conditions.