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| Study on chlorine ion washing and cement solidification in MSWI fly ash |
| NING Huayu |
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Abstract The elution influence of the washing pre-treatment process with deionized water on soluble chlorine in MSWI fly ash and the optimum processing were studied. Moreover, the strength (3 d and 28 d) and microstructure (morphology and distribution of crystal phase) of blended cements with different content of the treated MSWI fly ash were researched. The results showed that associated with the washing process in the liquid-solid ratio of 10, most of the chloride ions in MSWI fly ash could be removed. The improvement of the liquid-solid ratio could also increase the amount of chlorine removal, but with a limited impact. There was not directly relationship between washing time and the washout rate of chloride ion. The washed and unwashed MSWI fly ash as a cement mixing material, involved in the cement hydration process, would generate expansion and cracking phenomenon, and with the addition of fly ash and the phenomenon is more obvious. The early strength of cement block that adding 10% fly ash close to that non-doped fly ash, but the latter strength should be decreased intensity. The early strength and latter strength of cement block that mixing 20%, 30% and 40% fly ash were very close, but strength was only about half of the block non-doped fly ash. According to the SEM and XRD analysis, compared with the blank sample, the cement block that adding fly ash had less Ca(OH)2 crystal and crystal size was smaller, and containing more unhydrated SiO2.
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Published: 04 December 2018
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2018, Vol. 0 
