Browsing by Author "Araya-Letelier, G."

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    Experimental evaluation of adobe mixtures reinforced with jute fibers
    (2021) Araya-Letelier, G.; Antico, F. C.; Burbano-Garcia, C.; Concha-Riedel, J.; Norambuena-Contreras, J.; Concha, J.; Flores, E. I. Saavedra
    Due to their sustainability as well as physical and mechanical performance, different natural fibers, both vegetal and animal fibers, have been successfully used in adobe mixtures (AMs) to enhance properties such as cracking control, flexural toughness and water erosion resistance, among others. However, the use of jute fibers (Fs), one of the most largely produced vegetal fiber worldwide, has not been extensively studied on AMs. Consequently, this study evaluates the effects of the incorporation of varying dosages (0.5 and 2.0 wt%) and lengths (7, 15, and 30 mm) of JFs on the physical/thermal/mechanical/fracture and durability performance of AMs, a specific type of earth-based construction material widely used globally. Experimental results showed that the incorporation of 2.0 wt% dosages of JFs increased the capillary water absorption of AMs, which might affect AM durability. The latter result could be explained by the additional porosity generated by the spaces left between the JFs and the matrix of adobe, as well as the inherent water absorption of the JFs. The incorporation of JFs significantly improved the behavior of AMs in terms of thermal conductivity, drying shrinkage cracking control, flexural toughness and water erosion performance, without affecting their compressive and flexural strength. For example, flexural toughness indices were increased by 297% and crack density ratio as well as water erosion depth values were reduced by 93% and 62%, respectively, when 2.0 wt%-15 mm length JFs were incorporated into AM. Since the latter combination of JF dosage and length provided the overall best results among AMs, it is recommended by this study as JF-reinforcement scheme for AMs for construction applications such as adobe masonry and earth plasters. (C) 2020 Elsevier Ltd. All rights reserved.
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    Sulfate attack performance of concrete mixtures with use of copper slag as supplementary cementitious material
    (Springer Science and Business Media B.V., 2025) Silva Urrego, Yimmy Fernando; Burbano-Garcia, C.; Araya-Letelier, G.; Izquierdo, S.
    © 2025 The AuthorsOne of the most significant causes of concrete structural degradation is sulfate attack, stemming from the interaction between hydration products of cement and sulfate ions, which causes physical and microstructural changes in the material matrix that can severely affect concrete's mechanical performance. This study evaluates the short and long term (up to 360 days) sulfate resistance performance of concretes incorporating copper slag (CS), a major global mining waste, as supplementary cementitious material (SCM). Three concrete mixtures with increasing CS replacement levels (i.e., 0 %, 20 % and 50 % by volume replacement of ordinary Portland cement) were exposed to aggressive sulfate environment, specifically sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4) solutions, each containing 33,800 ppm of SO4–2. A comprehensive analysis of physical (linear expansion and visual inspection), mechanical (compressive strength and modulus of elasticity) and mineralogical (scanning electron microscopy (SEM) and X-ray diffraction (XRD)) properties was conducted. The results indicated that physical changes were most significant in the mixtures exposed to MgSO4 compared to those exposed to Na2SO4. Additionally, higher compressive strength losses at 360 days were observed, with reductions of 18 %, 21 % and 15 % for the mixtures with 0 %, 20 % and 50 % of CS as SCM, respectively. The elastic modulus results showed a similar trend to compressive strength, with the 20 % CS mixture exhibiting comparable stiffness to the reference, while the 50 % CS mixture showed a noticeable reduction. In mineralogical terms, characteristic crystals such as ettringite and gypsum were identified in all exposed concretes by XRD and SEM. Finally, these findings demonstrate that incorporating CS as an SCM does not adversely affect the sulfate resistance of concrete mixtures and supports its potential use in durable, sustainable concrete applications.