Browsing by Author "Silva, Joaquim Pedro"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Manufacture of Ceramic Bricks Using Recycled Brewing Spent KieselguhrPublication . Ferraz, Eduardo; Coroado, João; Silva, Joaquim Pedro; Gomes, Celso; Rocha, FernandoIn the brewing process, kieselguhr performs as a filtration medium and one generated by-product is a sludge containing kieselguhr, which is mainly composed of fragmented diatom frustules associated to organic material retained during the clarification process. The physic-mechanic tests were performed on assemblages with brick composition and brewing spent kieselguhr containing 3, 9, and 15 wt% incorporation levels of sludge, being extruded and dried (105ºC) before being submitted to slow firing at 900ºC, 950ºC, and 1000ºC. The obtained results showed that, even when at its maximum incorporation level, the spent kieselguhr for all firing temperatures do not cause important losses on the properties exhibited by the clay paste without kieselguhr incorporation and the best incorporation levels are 4.2 wt% when fired at 900ºC, 9.8 wt% when fired at 950ºC, and 13.4 wt% when fired at 1000ºC. When fired at 950ºC, 15 wt% addition of spent kieselguhr increased by 27% the open porosity and decreased by 10% the bulk density of the brick paste. Furthermore, physic-mechanic tests and ecotoxicity evaluation on semi-industrial brick manufactured with 9 wt% of brewing spent kieselguhr were accessed. The results do no show any constrain concerning mechanical properties, and the ecotoxicity evaluation shows the safety of the brewing spent kieselguhr incorporation in ceramic products.
- Spent brewery grains for improvement of thermal insulation of ceramic bricksPublication . Ferraz, Eduardo; Coroado, João; Gamelas, José; Silva, Joaquim Pedro; Rocha, Fernando; Velosa, Ana LuísaOne by-product of the brewing process is a waste containing spent grains (barley malt and maize grits). In the brewing process, this cake is composed mainly of organic matter containing high fiber content, provided by the separation of suspended particles through wort filtration. The study presented here was carried out to assess if the spent brewery grains could be recycled through their incorporation in a paste used in the manufacture of ceramic bricks, and how such incorporation affects some of the physical properties, namely mechanical strength, porosity, and thermal conductivity of the ceramic material. The main objective of the study was to decrease the thermal conductivity of the ceramic paste without significant losses of the mechanical strength of the final product. Spent brewery grains (SBG) characterized by powder X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, thermogravimetry, differential scanning calorimetry, and heat of combustion were used as an additive (pore-forming agent) to a brick paste, characterized by powder X-ray diffraction, particle-size analysis, mechanical strength, plasticity index, and thermal conductivity determinations. Powder mixtures obtained by addition of 5, 10, and 15% by weight of dry SBG to brick raw material (SBG-to-brick paste weight) were assembled. The powder mixtures were extruded and the green probes were dried (105°C) before slow firing at 900, 950, and 1,000°C. Drying and firing shrinkages and mechanical bending strengths were investigated in addition to bulk density, open porosity, water absorption, and thermal conductivity of the fired samples. The mixture of ceramic paste with SBG fired up to 900°C with an incorporation of SBG of 5% by weight was found to reach a compromise between the highest mechanical bending strength (15 MPa) and the lowest thermal conductivity (0.46 Wm−1K−1). When compared with the ceramic paste without SBG incorporation, a diminution of 12 and 28% of the values of these properties, respectively, was obtained.