Examinando por Materia "Auto-combustion"

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    Assessment of sugar cane straw ash (SCSA) as pozzolanic material in blended portland cement: Microstructural characterization of pastes and mechanical strength of mortars
    (Elsevier, 2015-09) Moraes, J. C. B; Akasaki, Jorge Luis; Melges, J. L. P.; Monzó Balbuena, José Mª; Borrachero Rosado, María Victoria; Soriano Martínez, Lourdes; Paya Bernabeu, Jorge Juan; Tashima, Mauro Mitsuuchi; Departamento de Ingeniería de la Construcción y de Proyectos de Ingeniería Civil; Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos; Instituto Universitario de Investigación de Ciencia y Tecnología del Hormigón; Ministerio de Educación, Cultura y Deporte; Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brasil
    The aim of this paper is to assess the pozzolanic reactivity of sugar cane straw ash (SCSA) obtained through an auto-combustion process and the mechanical properties of SCSA-containing systems. Characterization of SCSA (X-ray diffraction, chemical composition, particle size, and microscopy) and reactivity studies on hydrated lime/SCSA and Portland cement/SCSA pastes through infrared spectroscopy, thermogravimetric analysis, and microscopy demonstrated the high pozzolanic activity. This reactivity made it possible to achieve good mechanical properties in mortars in which 15 30% of the cement was replaced by SCSA. After 90 days of curing, the SCSA fixed 100% of the lime present in lime/SCSA pastes, and the compressive strength of mortars containing SCSA reached 44 MPa, a value similar to those found for control mortars after the same number of curing days. The results for the microstructural and mechanical properties showed that SCSA is a good pozzolanic material.
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    Auto-Combustion of Corn Straw: Production and Characterization of Corn Straw Ash (CSA) for Its Use in Portland Cement Mortars
    (MDPI AG, 2024-09) Paya Bernabeu, Jorge Juan; Escalera, Alejandro; Borrachero Rosado, María Victoria; Rosello Caselles, Josefa; Monzó Balbuena, José Mª; Soriano Martínez, Lourdes; Departamento de Ecosistemas Agroforestales; Departamento de Ingeniería de la Construcción y de Proyectos de Ingeniería Civil; Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos; Instituto Universitario de Investigación de Ciencia y Tecnología del Hormigón
    [EN] Agricultural waste availability implies the possibility of recovering energy as biomass. The collateral effect is the production of ashes that, in some cases, have the potential to be reused in the manufacture of cement, mortar, and concrete. This article presents the study of the auto-combustion (unlike all previous studies) of corn (maize) straw (stems and leaves). The auto-combustion temperature was monitored, and the obtained corn straw ash (CSA) was characterized by means of X-ray fluorescence, X-ray diffraction, thermogravimetry, and scanning electron microscopy. Finally, the behavior of ground CSA was analyzed in both the fresh state by measurement of workability on the spreading table and the hardened state by compressive strength measurement on mortars in which 10% of ordinary Portland cement (OPC) was replaced with CSA. These values were compared to both a control mortar (OPC) and a mortar in which OPC was partially replaced with 10% limestone filler. Ashes showed adequate pozzolanic reactivity because, at 90 curing days, the compressive strength of the mortars with 10% replacement of OPC with CSA was practically equal (98% of the strength) to the control mortar without pozzolan replacement. The auto-combustion of biomass is a process that can be easily available, and the results on pozzolanic reactivity of CSA are satisfactory. The auto-combustion could be used by low-income communities to reduce Portland cement clinker use and to recover waste.
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    Production of bamboo leaf ash by auto-combustion for pozzolanic and sustainable use in cementitious matrices
    (Elsevier, 2019-05-30) Moraes, M.J.B.; Moraes, J.C.B.; Mitsuuchi Tashima, Mauro; Akasaki, J.L.; Soriano Martínez, Lourdes; Borrachero Rosado, María Victoria; Paya Bernabeu, Jorge Juan; Departamento de Ingeniería de la Construcción y de Proyectos de Ingeniería Civil; Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos; Instituto Universitario de Investigación de Ciencia y Tecnología del Hormigón; Fundação de Amparo à Pesquisa do Estado de São Paulo
    [EN] In the context of world concern with the environment, this study aims to characterize an auto combustion produced bamboo leaf ash (BLA) by its pozzolanic behaviour, reactivity and its influence in the total porosity, pore size distribution, tortuosity and mechanical behaviour of cementitious matrices. The chemical and physical characterization of the BLA was carried using X-ray fluorescence, determination of amorphous silica content, X-ray diffraction, Fourier Transform Infrared Spectrophotometry (FTIR), laser granulometry and field emission scanning electron microscopy (FESEM). The assessed BLA is a siliceous material (74.23%) with an amorphous nature due to the amorphous silica content, which represents 92.33% of the total silica. The BLA was classified as highly reactive by assessing its pH and conductivity in a saturated calcium hydroxide (CH) medium for different proportions and temperatures. Frattini analysis, the study of CH:BLA pastes (Thermogravimetric analysis and FTIR) and Portland cement (OPC)/pozzolan pastes (Thermogravimetric analysis and FESEM) are in agreement with this classification. The replacement of OPC by BLA improved the mechanical behaviour of the cementitious matrices, as well their durability. All the mortars containing BLA presented very similar compressive strength to a control mortar (100% OPC) after only 3 days of curing and at the following tested curing ages: 7, 28 and 90 days. In the mercury intrusion porosimetry analysis, the pastes with 20 and 30% BLA content presented higher tortuosity or fewer connected pores than the control paste. Thus, the auto-combustion method proved to be successful and BLA is a suitable alternative for sustainable high-performance matrices. (C) 2019 Elsevier Ltd. All rights reserved.