Resumo em Inglês:

Abstract This work reports a study on the effects of firing temperature on the technical properties of clay ceramic incorporated with blast furnace sludge (BFS) waste. For this, three clay ceramic pastes were formulated, partially replacing plastic clay with up to 10 wt.% of BFS waste. The clay ceramic pieces were shaped by pressing and fired in a muffle furnace between 900 ºC and 1100 ºC. The effect of firing temperature was evaluated by monitoring linear shrinkage, water absorption, apparent porosity, apparent density, and flexural strength. The BFS waste consists mainly of iron oxide (Fe2O3) and coke fines. It was also found that the firing temperature influenced the technical properties, resulting in relevant repercussions on the quality of the clay ceramic pieces incorporated with BFS waste. The results allowed us to conclude that sealing and structural ceramic blocks for masonry can be produced at firing temperatures between 900 ºC and 1000 ºC, while roofing tiles can be made at 1100 ºC.

Resumo em Inglês:

Abstract In this work, a comprehensive study was conducted to examine the impact of ammonium bicarbonate (NH4HCO3) content, a porogenic agent, on the development of the microstructure, compressive strength, and Young’s modulus of the porous silicon nitride ceramics using the sacrificial method. The porous ceramics were obtained by pressureless sintering at 1650 oC and characterized by scanning electron microscopy and X-ray diffraction. The findings demonstrated that all samples developed a microstructure with β-Si3N4 grains, but α-Si3N4 and wollastonite were also identified. Moreover, grains with a high aspect ratio are predominant in the pore inner structure. The pore morphology was changed from spherical to irregular when the highest NH4HCO3 content was used. Under this condition, interconnected pores were also present. The values of compressive strength and Young’s modulus decreased with increasing porogen content. The reduction was more pronounced for the ceramic prepared with the highest NH4HCO3 content.

Resumo em Inglês:

Abstract The ornamental rock industry is known for producing a significant amount of marble waste. In this investigation, a study was carried out on the formulation of ceramic masses for red wall tiles (BIII group) using marble waste as an ecological alternative to traditional limestone. The raw materials used (clay, quartz, limestone, and marble waste) were characterized in terms of chemical and mineral compositions. The formulation of the wall tile masses was guided by the triaxial diagram method. Tile pieces were produced by pressing and firing in the range of 1100 to 1180 °C. The influence of the incorporation of marble waste in the red wall tiles was evaluated through the gresification diagram. The results showed that the marble waste exhibited good chemical compatibility for use in red wall tile formulations. It was also found that all formulations incorporated with marble waste presented typical gresification behavior for the production of red wall tiles (BIII group of ABNT NBR ISO 13006). Thus, the ceramic tile industry could offer a sustainable alternative for the valorization of marble waste.

Resumo em Inglês:

Abstract The use of cisterns for water storage has been an alternative to supply water in regions with low rainfall, such as the Brazilian semi-arid region. Several studies have been conducted, proposing the use of different materials for the construction of cisterns. This research analyzed some quality parameters of water stored in cisterns. Two prototype cisterns were built, one with conventional mortar and the other composed of mortar with tire rubber residues, expanded vermiculite, and sisal fibers. The evaluated water quality parameters were: pH, alkalinity, conductivity, turbidity, true color, and apparent color at ages of 24 hours, 7 days, 30 days, 60 days, and 90 days. The results were compared to those obtained from a plastic bench cistern and indicated an increase in pH, alkalinity, and conductivity, which indicates and confirms the formation of salts caused by the cementitious material.

Resumo em Inglês:

Abstract This work aimed to evaluate the valorization potential of mollusk shell waste as a renewable source of calcium carbonate to produce calcium titanate ceramic through a solid-state reaction method. The calcium titanate ceramic powders synthesized from the molar ratio CaCO3:TiO2 (1:1) between 900 and 1200 ºC were characterized regarding the X-ray diffraction (XRD), thermogravimetric-differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FTIR), and electrical resistivity. The results indicated that the mollusk shell waste was primarily composed of calcium carbonate in the form of aragonite. The results also showed the formation of an orthorhombic-structured calcium titanate (CaTiO3) at different synthesis temperatures. Additionally, it was found that the calcium titanate powders had an average crystallite size in the range of 43 to 49 nm and volume electrical resistivity in the range of 3.80 - 4.89 x 109 Ωcm. Therefore, the mollusk shell waste is highly promising for obtaining calcium titanate ceramic for electroceramic applications.