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Araya-Letelier, G., Antico, F. C., Burbano-Garcia, C., Concha-Riedeld, J., Norambuena-Contreras, J., Concha, J., et al. (2021). Experimental evaluation of adobe mixtures reinforced with jute fibers. Constr. Build. Mater., 276(2021), 122127.
Abstract: 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 (JFs), 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.
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Norambuena-Contreras, J., Arteaga-Perez, L. E., Guadarrama-Lezama, A. Y., Briones, R., Vivanco, J. F., & Gonzalez-Torre, I. (2020). Microencapsulated Bio-Based Rejuvenators for the Self-Healing of Bituminous Materials. Materials, 13(6), 16 pp.
Abstract: Asphalt self-healing by encapsulated rejuvenating agents is considered a revolutionary technology for the autonomic crack-healing of aged asphalt pavements. This paper aims to explore the use of Bio-Oil (BO) obtained from liquefied agricultural biomass waste as a bio-based encapsulated rejuvenating agent for self-healing of bituminous materials. Novel BO capsules were synthesized using two simple dripping methods through dropping funnel and syringe pump devices, where the BO agent was microencapsulated by external ionic gelation in a biopolymer matrix of sodium alginate. Size, surface aspect, and elemental composition of the BO capsules were characterized by optical and scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermal stability and chemical properties of BO capsules and their components were assessed through thermogravimetric analysis (TGA-DTG) and Fourier-Transform Infrared spectroscopy (FTIR-ATR). The mechanical behavior of the capsules was evaluated by compressive and low-load micro-indentation tests. The self-healing efficiency over time of BO as a rejuvenating agent in cracked bitumen samples was quantified by fluorescence microscopy. Main results showed that the BO capsules presented an adequate morphology for the asphalt self-healing application, with good thermal stability and physical-chemical properties. It was also proven that the BO can diffuse in the bitumen reducing the viscosity and consequently self-healing the open microcracks.
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Norambuena-Contreras, J., Gonzalez-Torre, I., Vivanco, J. F., & Gacitua, W. (2016). Nanomechanical properties of polymeric fibres used in geosynthetics. Polym. Test, 54, 67–77.
Abstract: Geosynthetics are composite materials manufactured using different types of polymeric fibres, usually employed as anti-reflective cracking systems in asphalt pavements. Materials that compose geosynthetics can be damaged due to mechanical and thermal effects produced during the installation process under hot mix asphalts. In this paper, different polymeric fibres extracted from geosynthetics have been evaluated using nanoindentation tests. The main objective was to evaluate the effect of installation process (dynamic compaction and thermal damage) on the mechanical behaviour of individual polymeric fibres at nano-scale. To do this, elastic modulus (E) and hardness (H) of three different polymeric fibres commonly used in geosynthetics (polypropylene, polyester and polyvinyl-alcohol), in two testing directions and under two different states have been studied. Main conclusions of this work are that mechanical properties of geosynthetics individual fibres can change after installation, producing changes in the behaviour of geosynthetics at macro-scale with consequences in the pavement functionality, and that these changes are different depending on the material that composed the fibres. (C) 2016 Elsevier Ltd. All rights reserved.
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