Depósito Académico
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131 results
Results
- Air lime renders with microencapsulated phase change materials: assessment of microstructural and thermal properties(Elsevier, 2024-11-22) Alvarez-Galindo, J.I. (José Ignacio); Rubio-Aguinaga, A. (Andrea); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)Microencapsulated phase change materials (PCMs) have been successfully integrated into air lime-based rendering mortars to enhance thermal properties, aiming to boost the thermal efficiency of the buildings in which are applied. Two microencapsulated PCMs, with melting points at 18℃ and 24℃, were seamlessly introduced into fresh rendering mortars in varying proportions (5%, 10%, and 20% by weight of lime), in formulations that include different chemical additives, such as a superplasticizer (polycarboxylate ether) and an adhesion enhancer (starch-based additive). In some mixes, metakaolin (MK) was also added as a mineral admixture. Starch addition was seen to promote the formation of aragonite and vaterite (calcium carbonate polymorphs), facilitating the smooth integration of microcapsules within the lime matrix. Hotbox simulations with tested materials containing as low as 0.01 - 0.04 g of PCM per gram of dry mortar, yielded outstanding energy efficiency values (822.4 and 732.8 kJ/m2, respectively, for PCMs with melting points at 18℃ and 24℃). Temperature attenuations of up to 6.1°C during the heating stage and up to 3.9°C during the cooling stages were observed. This outcome not only emphasizes the potential for enhancing thermal efficiency through PCM incorporation into air lime renders but also hints at a remarkable future for energy-efficient construction materials.
- Transforming waste red mud into sustainable cementitious materials for self-cleaning applications(2024-12-11) Alvarez-Galindo, J.I. (José Ignacio); Navarro-Blasco, I. (Iñigo); Pavia, S. (Sara); Kaur, G. (Gurbir); Fernandez-Alvarez, J.M. (José María)The development of novel catalysts and photocatalytic materials is an active area of study in the field of remediation of air pollution. The aim of this study is to investigate the potential of red mud-based cement mortars for photocatalytic abatement of nitrogen oxides (NO and NOx) under solar irradiation. Red mud is an industrial by-product generated during the Bayer process for refining bauxite into alumina. It poses significant environmental challenges due to its highly alkaline nature and presence of toxic heavy metals. Typically, hematite (α-Fe2O3) and goethite (α-FeOOH) are the compounds or iron oxide phases which are found in abundance in red mud. Interestingly, hematite is a nontoxic and stable compound, which possesses a visible light active band gap and can be a potential catalyst for photocatalytic activity.
- Potential use of red mud in cementitious materials for environmental remediation(2024-10-21) Alvarez-Galindo, J.I. (José Ignacio); Navarro-Blasco, I. (Iñigo); Pavia, S. (Sara); Kaur, G. (Gurbir); Fernandez-Alvarez, J.M. (José María)Red mud (RM), an industrial waste derived from aluminum production, is a significant environmental concern due to its high alkalinity and large volumes. However, RM can be leveraged in the construction industry for wide variety of applications, including production of low-carbon cementitious materials and for environmental remediation. Using RM as a cement replacement reduces the need for raw materials typically used in cement production, such as limestone and clay. This helps conserve natural resources and reduces the environmental impact of mining. At the same time, it addresses other environmental concerns simultaneously by reducing waste and potentially lowering the carbon footprint of construction industry. This study explores the photocatalytic performance of RM, and its subsequent use in cementitious materials as partial cement replacement. Red mud is rich in iron oxide, which is distributed in mineral phases such as hematite (Fe2O3) and goethite (FeOOH). Hematite (α-Fe2O3) is the most stable form of iron oxide and can be significant for photocatalytic applications point of view. In the initial phase of this study, the photocatalytic activity of RM was assessed by means of an abatement test to measure NOx reduction in solar irradiation. It was observed that RM has a potential of photocatalytic removal of nitrogen oxides, attributed to the adsorption of NO and NOx, as well as their subsequent photocatalytic degradation. In second stage of the study, RM-based cement mortars were prepared, and based on variables i.e., RM’s substitution levels as cement replacement, workability and compressive strength of mortars were investigated. The thermal properties and phase transitions of the investigated mortars were studied using thermogravimetric analysis (TGA). The compressive strength of RM-cement mortar at 28 days with optimal conditions (5% RM substitution) i.e., C3R5 is 31.19 MPa, showing 41% improvement over standard cement mortar. Scanning electron microscope (SEM) micrographs reveal abundant hydration products and strong interfaces in C3R5. By offering an environmentally friendly solution to RM management while simultaneously creating useful construction materials, this study represents a significant step towards more sustainable industrial practices and resource utilization.
- Optimization of Air Lime Concrete and Air Lime-based Ternary Mixtures with Sustainable Additives for Enhanced Performance in Heritage Buildings(2024-10-21) Alvarez-Galindo, J.I. (José Ignacio); Kyriakou; Çam, E. (Elif); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)The urgent need for sustainable, carbon-negative construction materials has been intensified due to global warming (Barbhuiya, 2023; Haik, 2020). Historic buildings face unique challenges in integrating eco-friendly parameters due to the necessity of compatibility of new materials with historic structures and mitigating their long-term impacts (ICOMOS, 2003). The replacement of OPC with lime in concretes and mortars enables lower carbon emissions and compatibility with historic buildings, although it exhibits higher porosity, water absorption and lower compressive strength than OPC (González-Sánchez, 2021; Rosell, 2023; Velosa, 2009). In this case, admixtures are used to improve the performance of lime-based mixes (Grist, 2013; Seabra, 2009). The study focuses on optimising lime concrete and air lime-based ternary mixes by incorporating eco-friendly additives, as different pozzolanic agents and fibres, to enhance their physical and mechanical properties to be used in restoration works. Silica fume, which is a by-product, and natural volcanic ash were selected as pozzolanic agents and added in different percentages between 0–30%. Hemp and basaltic fibres were included in 1%. The study evaluated the effects of different binders and additives through analyses such as fluidity, water retention, and setting time, also compressive strength tests (7th-28th days). The fresh state analyses revealed that adding silica fume reduced the slump values of the mortars by 13%, whereas volcanic ash and fibres had no significant impact on these values. It was also observed that mixtures containing volcanic ash exhibited lower water retention than those with silica fume. Additionally, the inclusion of basalt fibres reduced water retention in the lime-based ternary mortar by up to 4% compared to those containing hemp fibres. According to mechanical tests, cement and silica fume contributed to the compressive strength values of lime-based mixtures. However, volcanic ash and fibres negatively affected compressive strength values in the early stage. As a conclusion, using silica fume and cement in lime-based mixtures reduces the workability of mortars, contrary to volcanic ash and fibres, while increasing mechanical properties even in the early stages.
- Preparation of multifunctional superhydro- and hydro-oleophobic coatings with self-cleaning capacities for construction materials(2024-10-21) Alvarez-Galindo, J.I. (José Ignacio); Navarro-Blasco, I. (Iñigo); Tena-Santafé, V.M. (Víctor M.); Fernandez-Alvarez, J.M. (José María)Versatile coatings were developed to protect mortar surfaces across a broad range of applications, from preserving architectural heritage to modern civil engineering projects. These coatings utilize super-hydrophobic (SPHB) and hydro-oleophobic (OHB) materials, incorporating a nanostructured photocatalyst (Bi2O3-ZnO 8/92). To prevent the aggregation of the nanophotocatalyst, non-ionic dispersants such as Brij35, TritonX-100, and Tween20 were added. The coatings were applied to lime and limecement mortar substrates, and their properties¿such as hydro- and oleo-repellence, photocatalytic activity (through NOx abatement studies), and self-cleaning performance (dye degradation studies)¿were evaluated. Generally, mortars with SPHB coatings exhibited higher photocatalytic activity compared to those with OHB coatings. To simulate real-world conditions, the samples underwent artificial climate aging to assess their durability. Microstructural examination by SEM was addressed to evaluate the alteration degree of the coatings. Their retained effective hydrophobic properties, photocatalytic activity, and self-cleaning performance even after accelerated weathering tests. Future studies aim to apply these coatings to earthen mortars and earthen building materials, in particular by improving the hydrophobicity of the materials.
- Green way of improving the thermal efficiency of mortars by the addition of biobased phase change materials(MATEC Web of Conferences, 2024-09-16) Alvarez-Galindo, J.I. (José Ignacio); Rubio-Aguinaga, A. (Andrea); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)The thermal efficiency of air lime-based mortars was improved by directly integrating varying amounts (5 wt. %, 10 wt. %, and 20 wt. %) of a biobased Phase Change Material (PCM) into the fresh mortars. The composition of this PCM is vegetable oils and other organic wastes from the agri-food sector. To optimise the mortar formulation, different chemical additives and mineral admixtures were added. The mortar formulation was meticulously designed to produce rendering mortars that are easily workable, crack-free, and fully adherent for use in building envelopes. Positive outcomes in thermal efficiency tests have demonstrated the ability of these materials to store thermal latent energy, offering an environmentally friendly alternative to enhance the thermal comfort of building inhabitants.
- Vaterite Calcined Clay Cement (VC3) as a Low-Carbon Solution(2024-10-21) Alvarez-Galindo, J.I. (José Ignacio); Kyriakou; Rubio-Aguinaga, A. (Andrea); Navarro-Blasco, I. (Iñigo); Nofalah, M.H. (Mohammad Hossein); Fernandez-Alvarez, J.M. (José María)Climate change, driven by rising CO2 levels, is a critical global challenge. Portland cement production, exceeding 4 Gt/year with demand projected to rise by 50%, significantly contributes to this issue. Consequently, there's growing interest in developing low-carbon cementitious binders to reduce the construction industry's environmental impact. This study explores vaterite, a metastable calcium carbonate polymorph, for its potential to enhance cementitious materials' sustainability and performance. Vaterite Calcined Clay Cement (VC3) is investigated as a lowCO2 alternative to traditional cement. Vaterite can sequester approximately 0.44 kg CO2 per kg produced and potentially has a lower manufacturing carbon footprint. Recent advancements have made large-scale vaterite production economically viable, contributing to significant CO2 emission reductions. A scalable vaterite production method was applied utilizing a rapid precipitation technique involving mixing at a 2:1:1 molar ratio of K2CO3, CaCl2, and NH4Cl solutions, followed by filtration and ethanol treatment. This method yields high-purity vaterite making it well-suited for cement applications. The study investigated the effects of varying vaterite content, cement reduction levels, and Metakaolin-to-Vaterite (MK/V) ratios on the compressive strength, and fresh state characteristics of VC3 formulations. Results demonstrated an enhancement of long-term compressive strength (ca. 60% to 80%) of OPC mortar at 28 days when replacing calcite with vaterite up to 15%. Reduction in cement content to 45% and 40% of the total binder proportion, resulted in average compressive strength decreases of 17% and 23%, respectively. Furthermore, results demonstrated that by decreasing MK/V ratio from 3 to 1, compressive strength increases from 20MPa to ca. 27 MPa, that indicates potential pathways for more sustainable formulations. Rheological analysis demonstrated that vaterite improves flowability about 5% compared to calcite, addressing a challenging aspect of traditional Limestone Calcined Clay Cement (LC3) systems. By increasing MK/V ratios from 1 to 3 a decrease in workability of ca. 6% is observed. The effectiveness of polycarboxylate ether (PCE) superplasticizer in enhancing rheology was confirmed across various mix designs. This comprehensive approach to VC3 optimization offers promising pathways for developing high-performance, low-carbon cementitious materials, contributing to the sustainable future of the construction industry and potentially enabling carbon capture at gigaton scales.
- Optimized Phase Change Material-Enhanced Lime Renders for Energy-Efficient Building Envelopes: Thermal and Durability Characterization(2024-10-21) Alvarez-Galindo, J.I. (José Ignacio); Kyriakou; Rubio-Aguinaga, A. (Andrea); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)The construction sector's substantial contribution to global energy consumption and carbon emissions necessitates the development of innovative, sustainable building materials (PachecoTorgal et al., 2014; UN Environment Programme, 2019; Fei et al., 2021). Lime mortars, traditionally used as renders for building envelopes, are experiencing renewed interest due to their low environmental impact and compatibility with heritage conservation (Campo and Grosso, 2022; Manoharan and Umarani, 2022; Rodriguez-Navarro et al., 2023). This research focuses on the optimization of lime renders through the incorporation of microencapsulated Phase Change Materials (PCMs), specifically PCM24 and PCM18, which exhibit melting temperatures of 24°C and 18°C, respectively. These PCMs are designed to enhance thermal regulation in different climatic zones by storing and releasing heat at temperatures critical to building comfort (Saffari et al., 2017; Li et al., 2021). The optimized lime renders were formulated with the simultaneous addition of a superplasticizer, an adhesion booster, and a pozzolanic agent, ensuring improved workability, adhesion, and durability, key factors for their application in building envelopes. This study emphasizes the need to not only improve the energy efficiency of the material but also ensure its long-term durability, as sustainable construction requires materials that maintain performance over extended periods (Cunha, Aguiar and Ferreira, 2017).
- Green way of improving the thermal efficiency of mortars by the addition of biobased phase change materials(MATEC Web of Conferences, 2024-09-16) Alvarez-Galindo, J.I. (José Ignacio); Rubio-Aguinaga, A. (Andrea); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)The thermal efficiency of air lime-based mortars was improved by directly integrating varying amounts (5 wt. %, 10 wt. %, and 20 wt. %) of a biobased Phase Change Material (PCM) into the fresh mortars. The composition of this PCM is vegetable oils and other organic wastes from the agri-food sector. To optimise the mortar formulation, different chemical additives and mineral admixtures were added. The mortar formulation was meticulously designed to produce rendering mortars that are easily workable, crack-free, and fully adherent for use in building envelopes. Positive outcomes in thermal efficiency tests have demonstrated the ability of these materials to store thermal latent energy, offering an environmentally friendly alternative to enhance the thermal comfort of building inhabitants.
- Incorporación de materiales de cambio de fase(2024-09-27) Alvarez-Galindo, J.I. (José Ignacio); Rubio-Aguinaga, A. (Andrea); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)El mortero de cal se utiliza desde la antigüedad por sus propiedades mecánicas y durabilidad, lo que lo ha convertido en un material fundamental para la construcción de edificios históricos. Sin embargo, en las últimas décadas, su aplicación ha evolucionado. Hoy en día, no solo se utilizan en la restauración del patrimonio arquitectónico, sino también en proyectos que buscan sostenibilidad y eficiencia energética. Esta evolución ha abierto el camino a nuevas investigaciones, como la incorporación de materiales avanzados, como los materiales de cambio de fase (PCMs a partir de ahora por sus siglas en inglés), para mejorar su rendimiento térmico sin perder las características tradicionales del mortero.