Sulphate attack resistance of mortar containing spent bleaching earth ash
In this study, the spent bleaching earth ash (SBEA) was used as partial cement replacement to determine its effects on the sulphate resistance of mortar. Sulphate attack resistance of concrete containing SBEA has been studied previously and acknowledged to enhance the sulphate resistance of concrete...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/39112/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/39112/2/FULLTEXT.pdf |
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| Summary: | In this study, the spent bleaching earth ash (SBEA) was used as partial cement replacement to determine its effects on the sulphate resistance of mortar. Sulphate attack resistance of concrete containing SBEA has been studied previously and acknowledged to enhance the sulphate resistance of concrete. However, the knowledge on the effect of particle size and level of replacement of SBEA on sulphate attack resistance of mortar is still limited. The physical, chemical, mineralogical and microstructural properties of unground spent bleaching earth ash (USBEA) and ground spent bleaching earth ash (GSBEA) were characterized by using laser particle analysis, X-ray fluorescence (XRF), X-diffraction (XRD), and scanning electron microscope (SEM). The use of USBEA and GSBEA as cement replacement at 10, 20, 30, 40, and 50% were prepared for mortar mixture in this study. The pozzolanic activity of SBEA was evaluated through strength activity index (SAI) test at 7, 28, and 90 days. The effect of USBEA and GSBEA on the expansion of mortar bar after being immersed in 5% sodium sulphate solution was evaluated according to ASTM C1012 by measuring the length change of mortar bars at 1, 2, 3, 4, 8, 13, 15 weeks and subsequent length change was measured at 4 and 6 months. The grinding process of GSBEA resulted in smaller particle size (704 m2/kg) and higher specific surface area than USBEA (390 m2/kg). It was found that 40% of GSBEA showed the highest SAI with 135.16% and 136.17% at 28 and 90 days compared to other specimens. The expansion of mortar bar containing 40% GSBEA also showed the lowest expansion value (0.01%) at 6 months. Lower amount of calcium hydroxide (CH) was determined on mortar containing 40% GSBEA showing that it was consumed through pozzolanic reaction to form additional calcium silicate hydrate (CSH). Based on the SEM analysis, CSH was found in mortar containing 40% of GSBEA. This study also discovered that replacing cement with 40% of GSBEA reduced the expansion of mortar due to sulphate attack. Therefore, 40% of GSBEA as partial cement replacement has the potential to improve the sulphate resistance of mortar. |
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