The total eight clay brick samples including five archaeologically importance samples from different historical sites and three samples from more than a century old buildings of Kathmandu valley were collected and their mineralogical phases were characterized using X-ray diffraction and Fourier transform infrared spectroscopic methods in this study. Mineralogical phases existed in these archaeological and ancient clay bricks are identified as quartz, feldspars, spinel, muscovite, margarite and hematite in accordance with the powder diffraction standard files. The degree of the disappearance of feldspars phase and appearance of the spinel phase in all the brick samples is found to be different indicating that the firing temperature applied to produce these brick specimens should not be same. The firing temperature applied for the production of the eight clay brick samples should be in the range of 900°-1000° C. Most of the archaeological clay brick samples used in this study should be produced by firing at the high-temperature comparison with those brick samples used in old buildings of Kathmandu valley.
Present research work was focused to investigate the firing temperature effects on mineralogical phase composition of nine clay bricks collected from the brick factory of Kathmandu valley using X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra analyses. Main mineralogical phases of quartz, feldspars, spinel, mullite and hematite in the brick specimens fired at different firing temperatures including muscovite type of mica mineral in the sun-dried brick specimen are identified from XRD and FTIR analyses. Disappearance of the muscovite type of mica clay mineral with feldspars enhanced to form alumina rich spinel phase at firing 900° to 1000° C, and finally the primary mullite phase in the fired clay brick samples is clearly observed at 1100° C firing temperature.BIBECHANA 16 (2019) 122-130
The mineralogical phase of eight different types of contemporary and historical ceramic tile samples used in Kathmandu valley of Nepal was analyzed using their X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra to assess their quality. Mineralogical phases existed in these eight different tile samples, i. e., three wall, three floor and two ancient tile sample specimens, used in this study are identified as quartz, feldspars, spinel, mullite and hematite including paragonite with the help of the corresponding Joint Committee for Powder Diffraction Standards (JCPDS) database files. The firing temperature applied during the time of these ceramic tiles production should be 1000° C or slightly more. The mineralogical compositions of the contemporary tile samples are found to be comparable with those of the ancient brick samples of the historical temples and monuments of Kathmandu valley of Nepal.
Usages of various ceramic products have been recently attracted more attention than the counterpart of metallic and polymeric materials in scientific community [1,2], because the ceramic products have advantageous physical, chemical, refractoriness, strength retention at high temperature, high melting point and good mechanical properties [3-5]. Early evidence of the uses of the clay-based ceramic products was found in Harappan, Chinese, Greek civilizations, etc. [3,5]. For example, it was reported that the glazed tile was used to decorate the wall of the famous Tower of Babel and the Ishtar Gate in the ancient City of Babylon about 562 BC [3]. Clay tiles are generally used as coverings for floor, wall, facade or roof and can ranges from simple square tiles to complex mosaics and they are generally classified into six different types depending on their water (moisture) absorption capacity as well as their shaping or production methods. They are fully vitrified also called porcelain tile, semi-vitrified, terracotta, glazed porous, glazed vitrified and mosaics tiles [6]. However, all types of these clay tiles should be durable, rigid, hygienic, non-combustible and fire resistant with
Effect of firing temperature on some physico-mechanical properties of ten brick samples, those were composed by feldspars, quartz, alumina-rich spinel, primary mullite and hematite phases, was investigated in accordance with ASTM standards. The brick samples fired between 700° to 1100° C showed 11-23 % water adsorptivity (WA), 19-37 % apparent porosity (AP) and 1.50-1.65 g/cm3 bulk density (BD) indicate good physical properties. The maximum compressive strength (CS) of the fired-bricks at 950° to 1000° C was found to be between 15.6 and 17.1 MPa. At 700°-1000° C firing temperatures, the CS of these bricks is found to be increased exponentially with decreasing of both WA and AP, however it is found to be increased with increasing the BD. Consequently, it can be said that there is good correlation between mechanical and physical properties of the fired-brick samples up to the firing temperature of 1000° C.
Bangladesh J. Sci. Ind. Res.55(1), 43-52, 2020
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