BUSCADOR RECOLECTA

Tricalcium aluminate (Ca3Al2O6) is an indispensable component of Portland cement due to its high strength and reactivity. This study investigates the equilibrium lattice structure as well as the electronic and refractory properties of a newly discovered allotrope of Ca3Al2O6 using density functional theory and random phase approximation methods. Using density functional perturbation theory, we investigate the phonon dispersion of the refined structure's experimental stability. In addition, the lattice thermal conductivity and thermoelectric figure of merit are computed by solving the Boltzmann Transport Equation with the modified Debye Callaway model and the Relaxation time Approximation methods. The computed Figure of merit, determined by the carrier concentration, indicates a substantial enhancement of 40 to 100-fold, leading to a superior figure of merit of 0.25 and 0.6 when appropriately doped. As a result, we anticipate that stable allotropes of Ca3Al2O6 in the Pm3̄m phase will be useful as energy-harvesting, convective cooling and infrared radiation shield-based cement materials in the cement and concrete industries., 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)., The project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreements No. 964450 (MIRACLE project, www.miracle-concrete.eu) and No 870114 (NRG-STORAGE, https://nrg-storage.eu) from the EU Commission. We also acknowledge funding from the Spanish Ministry of Science and Innovation (grants nos. PID2022-137845NB-C22, PID2022-139230NB-I00, TED2021-132074B-C31, and TED2021-132074B-C32), the Gobierno Vasco UPV/EHU (project no. IT-1569-22), the Diputación Foral de Gipuzkoa (Project No. 2023-CIEN-000077-01). The support of the LTC Green Concrete is also acknowledged. Jorge S. Dolado acknowledge the CESGA supercomputing center for access to computing resorces., Peer reviewed

This study computationally investigates the effect of thermal energy storage (TES) material surface roughness on heat transfer fluid (HTF) flow dynamics and heat transfer capabilities. The motivation is to further understand systems where concrete as the TES material directly interfaces with air as the HTF, based on previous research suggesting potential benefits of avoiding differential thermal expansion issues associated with metallic tubes. A k-ε turbulence model in COMSOL Multiphysics examined air flow over concrete surfaces with five levels of roughness from 0 to 3 mm peak height. Increasing surface roughness enhances turbulence and significantly improves heat transfer and thermal storage performance, with 7 % higher charging efficiency and energy storage capacity and 55.6 % greater heat transfer rate from 0.3 to 3 mm roughness, despite a 138 % increase in pressure drop. Applying artificial surface modifications like indentations or fins could further optimize efficiency by amplifying heat transfer advantages of increased roughness while moderating pressure losses. This indicates a promising direction for future research on enhancing thermal energy storage through concrete surface optimization and substantiates the potential of concrete as an inexpensive, scalable, high performance TES material., This work was born under the umbrella of the project “Energy storage solutions based on concrete (E-CRETE)” (RTI2018-098554-B-I00) funded by MCIN/AEI/10.13039/501100011033 (Program I+D+i RETOS INVESTIGACIÓN 2018) and PCTE (PID2022-137845NB-C22) funded by MCIN/AEI/10.13039/501100011033. Mohammad Rahjoo acknowledges the grant PRE2019-087676 funded by MCIN/AEI/10.13039/501100011033 and co-financed by the European Social Fund under the 2019 call for grants for predoctoral contracts for the training of doctors contemplated in the State Training Subprogram of the State Program for the Promotion of Talent and its Employability in R&D&I, within the framework of the State Plan for Scientific and Technical Research and Innovation 2017–2020. In addition, the economic support from POVAZSKA is acknowledged. Jorge S. Dolado acknowledges the funding from the Gobierno Vasco UPV/EHU (project no. IT1569-22). This work is partially funded by Ministerio de Ciencia e Innovación—Agencia Estatal de Investigación (AEI) (RED2022-134219-T)., Peer reviewed

Several experimental studies have been conducted on the thermoelectric properties of cementitious materials, but a detailed inspection of the intrinsic properties of their main ingredients is still missing. This work focuses on the thermoelectric properties of portlandite and tobermorite, two mineral components found in Ordinary Portland Cement pastes. To this end, atomistic simulations were carried out to predict the thermoelectric properties of cement-based materials. The methodology is based on the density functional theory approach together with GW-quasiparticle and Boltzmann transport equation methods. As expected, the undoped minerals have low thermal conductivity. However, both the Seebeck coefficient and the electrical conductivity can be dramatically increased by appropriate carrier doping. In fact, an enhanced figure of merit of Z = 0.6 at 650 K and 0.79 at 600 K is observed for portlandite and tobermorite. Therefore, our results confirm that there are still much promising prospects for enhancing the characteristics of concrete materials for energy harvesting., The project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreements No. 964450 (MIRACLE project, www.miracle-concrete.eu) and No 870114 (NRG-STORAGE, https://nrg-storage.eu) from the EU Commission. We also acknowledge funding from the Spanish Ministry of Science and Innovation (grants nos. PID2022-137845NB-C22, PID2022-139230NBI00, TED2021-132074B-C31, and TED2021-132074B-C32), and the Diputación Foral de Gipuzkoa (SAREA/RED3023, Project No. 2023-CIEN-000077-01). The support of the LTC Green Concrete from the Basque Government is also acknowledged., Peer reviewed

This review was prepared by members of the working group 2 (Mohammad Rahjoo, Antonio Caggiano, Umberto Berardi, Achutha Prabhu, Jorge S. Dolado) within 299-TES: “Thermal energy storage in cementitious composites” and further reviewed and approved by all members of the 299-TES., Concrete has emerged as a promising solid-based sensible heat storage (SHS) material due to its favorable balance of thermal properties, cost-effectiveness, non-toxicity, and widespread availability. This state-of-the-art review examines the applications of concrete-based SHS across diverse domains, including buildings, concentrated solar power systems, and industrial power generation. It also investigates the thermal properties of concrete relevant for SHS applications and explores the design considerations for concrete SHS systems and reviews the current research landscape and the role of numerical modeling and simulation techniques in optimizing the performance of concrete SHS systems. Various computational methods, such as transient modeling, finite element method (FEM), computational fluid dynamics, and simplified lumped capacitance models, have been employed to analyze and enhance the design of these systems. As research and development continue in this field, several future trends are anticipated., MR and JSD acknowledge the grants TED2021-132074B-C31 and PID2022-137845NB-C22, funded by MICIU/AEI/10.13039/501100011033 and, as appropriate, by ‘ERDF A way of making Europe’, by ‘ERDF/EU’, by the ‘European Union’ or by the ‘European Union NextGenerationEU/PRTR’., Peer reviewed

Finding scalable, cost-effective and environmentally safe solutions for Passive Daytime Radiative Cooling (PDRC) is essential for addressing energy and climate challenges. This study demonstrates the feasibility of achieving PDRC using only cement-based compounds, without the need for additional whitening agents or other additives. Unlike previous approaches that rely on external additives, the proposed solution leverages two fundamental cement phases—portlandite and tobermorite—offering a scalable and low-impact alternative. The research evaluates the radiative cooling potential of these phases, along with two widely used cements—white cement (WC) and ordinary Portland cement (OPC), by analyzing and comparing their homogenized complex permittivities, derived using the Kramers-Kronig (KK) method. Simulations were conducted to assess the cooling power over one year across three different climates using actual meteorological data. The portlandite exhibits positive Pcool, maintaining a temperature equal to or below the ambient temperature more than 90 % of the time in dry desert and warm temperate locations. Indoor controlled measurements results reveal that portlandite (CH) may exhibit temperatures 15 °C lower than OPC and 5 °C lower than WC., The research presented in this paper has been supported by funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 64450 (MIRACLE project, more information available at www.miracle-concrete.eu) from the EU Commission. Additionally, this work has received financial support from the projects TED2021-132074B-C31, TED2021-132074B-C32 and TED2021-132074B-C33, funded by MCIN/AEI/10.13039/ 501100011033, and the European Union NextGenerationEU/PRTR and from the projects PID2022-137845NB-C21, PID2022-137845NB-C22 funded by MCIN/AEI/10.13039/501100011033/and by FEDER Una manera de hacer Europa.