A patchy particle model for C-S-H formation

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.The work described in this manuscript has been performed under InnovaConcrete EC project, supported by funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement N◦760858. AP and JSD also acknowledge the support received from the BASKRETE initiative and the Joint Transborder Lab-oratory (LTC) “Aquitaine-Euskadi Network in Green Concrete and Cement-based Material

Theoretical elastic constants of tobermorite enhanced with reduced graphene oxide through hydroxyl vs epoxy functionalization: A first-principles study

Graphene-based materials are considered excellent candidates to implement cementitious nanocomposites due to their mechanical properties. This paper presents a comprehensive interface interaction that ends up with computing the elastic properties for four models of the C–S–H gel, taking tobermorite 14 Å as an example, with reduced graphene oxide (rGO) to form reinforced (tobermorite) cementitious nanocomposites within the density functional theory. We found that upon relaxing the model structures, the dissociation of hydroxyl functional groups from the hydroxyl/rGO lattice occurs not only in the presence of Ca2+ ions to compensate for local charges but even when the Ca2+ charges are compensated with hydroxyl groups. In contrast, rGO/CSH interactions remained close to the initial structural models of the epoxy rGO surface. The elastic constants showed high improvements for the cementitious nanocomposite of tobermorite 14 Å with intercalated hydroxyl/rGO layers. Thus, the bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio increased up to limits set as 165, 128, 134, and 15% compared to tobermorite 14 Å, respectively. In more detail, the specific values of the elastic constants were influenced by the interface, specifically the presence of hydroxyl or epoxy groups as well as how the charges of the Ca2+ ions were compensated. These findings are of interest for the design of future experiments that will help to engineer better rGO/cement composites.This research was fully funded by Karlsruhe House of Young Science (KHYS) and Deutsche Forschungsgemeinschaft (DFG) with the project number of 446266595. A.A. and J.S.D. also acknowledge funding from the Spanish Ministry of Science and Innovation (grants nos. PID2019-105488GB-I00, PCI2019-103657 grant, PID2022-139230NB-I00, and TED2021-132074B-C32), the Gobierno Vasco UPV/EHU (project no. IT-1569-22), the European Commission NRG-STORAGE project (GA 870114), MIRACLE project (GA 964450), and NaturSea-PV (GA 101084348). Research conducted in the scope of the Transnational Common Laboratory (LTC) Aquitaine-Euskadi Network in Green Concrete and Cement-based Materials.Peer reviewe

Computational design of a Massive Solar-Thermal Collector enhanced with Phase Change Materials

Research conducted in the framework of MIRACLE Project (Photonic Metaconcrete with Infrared RAdiative Cooling capacity for Large Energy savings, GA 964450), coordinated by Dr. Jorge Sánchez Dolado, from Centro de Física de Materiales (CFM).A cement-based device that can meet, partially or completely, the heating loads of a building by absorbing the solar radiation and converting it into thermal energy can be defined as a Massive Solar-Thermal Collector. The absorbing material for the incoming radiation is made of a cementitious composite, generally concrete, and flowing water inside tubes acts as a heat transfer medium. For an optimized performance, during periods of solar radiation, the device has to efficiently conduct the heat flow from the absorbing surface of the collector and transfer this heat energy to the water. Then, when the radiation is reduced or became null, the device should retain as much as possible the heat energy, reducing the heat that is escaping the collector and consequently the losses to the surrounding environment. In this work, by performing a parametric analysis, different absorbing materials are tested with the objective of finding the best configuration that maximizes the energy efficiency of the collector. Cementitious materials, in combination with Phase Change Materials with distinct melting (and solidification) temperatures, are selected as candidate absorbing materials. The weather variables of an entire year and for two different locations are considered to evaluate the behavior of these devices in opposite climates. After numerical simulations, in where an enthalpy-based finite element formulation is used to solve the physical problem, the obtained results allow to conclude that the inclusion of Phase Change Materials within the absorber material of the collectors, if it is done in a correct way, can improve the energy performance of these devices. In this study, 34 °C and 53 °C are chosen as the most appropriated melting temperatures, which conduct to considerable improvements in the achieved performances, and in both warm and cold climates.The authors gratefully acknowledge the financial support from: - The National Scientific and Technical Research Council (CONICET) of Argentina. - The CONICET through the project “Computational design of functional thermal metamaterials in transient regime taking advantage of phase changes” (PIP 11220200101018CO). - The National Agency for the Promotion of Research, Technological Development and Innovation (AGENCIA) of Argentina through the project “Computational design of metamaterials applied to the development of thermal diodes for building envelopes” (PICT 2020 SERIE A 03765). - The National Technological University (UTN) of Argentina, for Grant PID MAUTNFE0007745. - The Technical University of Darmstadt, for the “Future Talent (Guest Stay)” and “Career Bridging” Grants, both given to the first author of this work. - The NRG-STORAGE project (870114, 2020-2024,https://nrg-storage.eu/), financed by the European Union H2020 Framework under the LC-EEB-01-2019 call, IA type. - The MIRACLE project (964450, 2021-2025,https://miracle-concrete.eu/), financed by the European Union H2020 Framework under the FETOPEN-01-2018-2019-2020 call, RIA type. - The support to networking activities provided by the PoroPCM Project (part of the EIG CONCERT - Japan funding,http:concert-japan.eu/) is also gratefully acknowledged.Peer reviewe

Early-stage analysis of a novel insulation material based on MPCM-doped cementitious foam: Modelling of properties, identification of production process hotspots and exploration of performance trade-offs

This study presents an early-stage design exploration of NRG-Foam, an innovative insulation material composed of cementitious foam doped with microencapsulated phase change materials (MPCMs). The study comprises the static part that utilizes life cycle assessment and life cycle costing assessment for getting insight into the impacts of the NRG-Foam production process and the dynamic part that identifies the trade-offs between performance characteristics of NRG-Foam using multi-objective optimization. The production of MPCMs was found to be a major contributor to environmental impacts while the addition of small amounts of reduced graphene oxide amplifies the impacts even further. The hot spot analysis pinpointed high electricity consumption as the main driver of environmental impacts. A multi-objective optimization analysis revealed trade-offs between performance characteristics, emphasizing the necessity of compromises during material development. The selection of the MPCM type was shown to be determinative of the final properties of NRG-Foam.This research was funded by the European Commission NRG-STORAGE project (project no. GA 870114).Peer reviewe

Appendix A. Supplementary data. Supplementary information: Early-stage analysis of a novel insulation material based on MPCM-doped cementitious foam: Modelling of properties, identification of production process hotspots and exploration of performance trade-offs

Multimedia component 1. S1. Costs used for LCCA calculations S2. Details of the modelling approach used in the dynamic part of the study S2.1. Parameters used for finding a Pareto frontier using gamultiobj Matlab function S2.2. Physical parameters of the components used for the calculations and modelling in this studyPeer reviewe