Browsing by Author "Navarrete Leschot, Iván Ignacio"
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- ItemFlue gas desulfurization (FGD) fly ash as a sustainable, safe alternative for cement-based materials(2021) Navarrete Leschot, Iván Ignacio; Vargas Muñoz, Felipe Andrés; Paul, Álvaro; López Casanova, Mauricio Alejandro; Martínez, Patricia; CEDEUS (Chile)The reduction in fly ash production in coal-fired power plants has created an opportunity to explore alternative types of fly ashes previously deemed unfit for use in concrete. In plants using flue gas desulfurization (FGD) processes, fly ash could contain high amounts of sulfur oxides, making its use in concrete inadvisable. However, the type of sulfur compound present in a fly ash strongly impacts its performance in concrete. In this study, two types of fly ash were used to evaluate the effect of sulfur oxides on mortar mixtures incorporating fly ash as supplementary cementitious material (SCM); one from an FGD unit, with high sulfur oxide content (in the form of hannebachite), and the other generated in a system without FGD, with negligible sulfur oxide. Calorimetry results show that hannebachite can effectively control C3A hydration similar to gypsum; however, its presence in FGD fly ash does not induce deleterious expansion associated with internal sulfate attack in mortars. TGA and XRD analyses suggest that hannebachite has lower reactivity than sulfate. Hannebachite not only maintains the pozzolanic reactivity of the fly ash, but its fineness may promote OPC hydration, increasing compressive strength. The results of this study indicate that FGD fly ash can be used as an SCM, allowing more sustainable concrete production.
- ItemHigh-performance and low-cost electrochemical reactor for limestone decarbonation applied to clinker production – A validation at laboratory scale(2024) Martínez, Natalia P.; Troncoso P., Felipe; Gazzano, Valeria; Ramírez Amaya, Darío Alonso; González Hormazábal, Marcelo Andrés; Navarrete Leschot, Iván Ignacio; Canales Muñoz, Roberto; Dreyse, PaulinaLimestone decarbonation to obtain CaO (calcium oxide) and produce cement is an industrial activity with enormous CO2 emissions, due to the intrinsic calcination reaction of CaCO3 (calcium carbonate), in addition to the use of fossil fuels. One of the most recent ideas to reduce CO2 emissions in this process has been the electrochemical decarbonation of limestone where Ca(OH)2 (calcium hydroxide) is obtained as an intermediate product that is then used as CaO precursor in clinker synthesis. This study shows the design of a low-cost electrochemical reactor and the optimization of the parameters to produce Ca(OH)2 with high purity and yield from the decarbonation processes of pure CaCO3 and limestone used in the cement industry. In addition, the remaining limestone sludge and electrolytic solutions were analyzed, and it was found that the sludge can be used as a correction material in clinker preparation, and it is also possible to reuse the electrolytic solution twice. Finally, the main finding is the proposal of a new clinker synthesis, which results in a cement with comparable characteristics to those of ordinary Portland cement, using Ca(OH)2 obtained from the electrochemical decarbonation of CaCO3, achieving a reduction in CO2 emissions of approximately 90% compared to the conventional method.
- ItemImpact of physical and physicochemical properties of supplementary cementitious materials on structural build-up of cement-based pastes(2020) Navarrete Leschot, Iván Ignacio; Kurama, Y.; Escalona, Néstor; López Casanova, Mauricio Alejandro; CEDEUS (Chile)
- ItemInfluences of Recycled Polyethylene Terephthalate Microplastic on the Hygrothermal and Mechanical Performance of Plasterboard with Polymethylhydrosiloxane Content(MDPI, 2024) Romano Matos, Victoria Enriqueta; Tundidor Camba, Alain; Vera Araya, Sergio Eduardo; Navarrete Leschot, Iván Ignacio; Videla Leiva, Álvaro Rodrigo; CEDEUS (Chile)New composites produced with recycled waste are needed to manufacture more sustainable construction materials. This paper aimed to analyze the hygrothermal and mechanical performance of plasterboard with a polymethylhydrosiloxane (PMHS) content, incorporating recycled PET microplastic waste and varying factors such as PMHS dose, homogenization time, and drying temperature after setting. A cube-centered experimental design matrix was performed. The crystal morphology, porosity, fluidity, water absorption, flexural strength, and thermal conductivity of plasterboards were measured. The results showed that incorporating recycled PET microplastics does not produce a significant difference in the absorption and flexural strength of plasterboards. However, the addition of recycled PET reduced the thermal conductivity of plasterboards by around 10%.
- ItemMineral admixture-based rheological design of concrete(2021) Navarrete Leschot, Iván Ignacio; López Casanova, Mauricio Alejandro; Kurama, Yahya C.; Pontificia Universidad Católica de Chile. Escuela de IngenieríaThe use of supplementary cementitious materials (SCMs; e.g., slag, fly ash) to reduce the amount of ordinary Portland cement in concrete construction has increased significantly over the last 20 years. Previous research has shown that, as an important benefit, SCMs can improve the long-term mechanical properties and durability of concrete. However, there is limited and inconclusive information on the relationship between SCM properties and concrete workability. This is particularly important for technologies that require high workability control, such as self-consolidating concrete (SCC). This thesis provides an experimental-based quantitative assessment and understanding of the effects of the particle size and physicochemical properties of SCMs and their interactions with the primary mixture parameters (such as water-to-cementitious materials ratio, SCM replacement, and reactivity of cement) on the rheology of cementitious paste (i.e., cementitious mixture with no coarse or fine aggregates). The results from this research are intended to improve the mixture design of new construction technologies that require better rheological control, through the use of SCMs. As a specific application, improved design of SCC to achieve better interlayer bonding is investigated. This is important for the construction of large concrete elements, where casting of multiple concrete lifts is required. Specifically, due to the lack of mechanical consolidation when casting SCC, the interfaces between multiple layers can result in reduced mechanical resistance in the final structure. The specific objectives of this research are to experimentally investigate, develop and validate empirical models for the effects of: 1) SCM properties and their interactions with the primary mixture parameters on the increase of static yield stress on time of cementitious paste before initial set; 2) SCM properties and their interactions with the primary mixture parameters on the viscosity of cementitious paste before initial set; and 3) concrete mixture design (i.e., cementitious paste rheology and aggregate-to-cementitious paste ratio), building process (i.e., layer-to-layer free-fall height and delay time), and their interactions on the layer-to-layer flexural and shear bond strength in multilayer SCC.
- ItemMulti-layer casting of self-consolidating concrete: Influence of mortar rheology and casting parameters on the inter-layer bond strength(2021) Navarrete Leschot, Iván Ignacio; López Casanova, Mauricio Alejandro; Kurama, Yahya; CEDEUS (Chile)Inter-layer bond strength is a critical factor to achieve structurally sound monolithic concrete structures. This paper discusses the effects of the cementitious paste volume (CP%vol), structural build-up of mortar (Athixm), and their interactions with casting parameters (i.e., free fall height (HFF), and delay time) on the residual bond strength of multi-layer self-consolidating concrete. It is found that the residual bond strength can be improved by increasing the CP%vol and HFF, or by reducing the delay time and Athixm. Out of the factors investigated, Athixm has the largest effect on both the residual bond strength and the critical delay time.
- ItemStratified concrete : understanding its stratification process and modelling its structural behavior(2015) Navarrete Leschot, Iván Ignacio; López Casanova, Mauricio Alejandro; Pontificia Universidad Católica de Chile. Escuela de IngenieríaEn vías de aumentar la eficiencia energética de las casas, la conductividad térmica del hormigón debe reducirse. El hormigón estratificado es producido a partir de una mezcla que es vibrada para obtener una capa liviana aislante y otra de peso normal estructural. El uso de paneles prefabricados ofrece la oportunidad de controlar el proceso de vibrado, esto es necesario para lograr una estratificación correcta. Sin embargo, cuando el panel es levantado, su peso propio induce tensiones por flexión que pueden superar los esfuerzos a los que será sometida la construcción. Esta investigación se divide en dos secciones: la primera sección estudia el efecto combinado de parámetros de diseño de mezcla de hormigón y características de la vibración en la segregación. La segunda sección se enfoca en el entendimiento del comportamiento a flexión para diseño y análisis de hormigón estratificado reforzado (RSC). Un modelo analítico de segregación fue desarrollado para evaluar el efecto de los parámetros de diseño de mezcla y las características de la vibración. Se concluyó que los parámetros de diseño de mezcla son más relevantes que las características de la vibración para controlar la segregabilidad. Además, la tasa de segregación es una propiedad intrínseca del hormigón y es independiente del tiempo de vibrado.
- ItemUnderstanding the effect of porosity on the mechanical and thermal performance of glass foam lightweight aggregates and the influence of production factors(2019) Arriagada, C.; Navarrete Leschot, Iván Ignacio; López Casanova, Mauricio Alejandro; CEDEUS (Chile)