| dc.description.abstract | Solid Recovered Fuel (SRF) co-firing fly ash which is produced by paper mills by using Circulating Fluidized Bed (CFB) have achieved the goal of waste recycling. However, some of SRF co-firing fly ash encounter the problems while back-end processing: (1) The instability of recycled products quality, (2) some cement products occurs expansion and cracking reactions. Therefore, this study aimed at the SRF co-firing fly ash (SRF-J and SRF-C) which have expansion tendency while mixing with cement, and carried out relevant pretreatment tests to provided a preliminary evaluation, offering the basis of judgement on the way of co-firing fly ash reuse.
In the initial results of study found that the expansion only occurred before hardened when co-firing fly ash maxing with cement, this phenomenon caused by the incomplete combustion of metallic aluminum in the CFB, a large amount of hydrogen will be generate when metal aluminum mixing with cement, and leads to expansion and cracks on specimen.
In addition, the gas release test was used establish a gas emission conversion function to estimate the metallic aluminum content in both of co-firing fly ash, and adopt un-treatment and pre-treatment to evaluate the potential of co-firing fly ash reuse. Un-treatment part select Controlled Low Strength Material (CLSM) test , and the pre-treatment part included water treatment, heat treatment, alkali solution treatment, and alkali-
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activated treatment. Among them, the alkali-activated treatment use slag blender material, and the other treatment use cement.
The test results show that it is invalid to make a sample as CLSM without treatment; the effect of water treatment is limited, cause the phenomenon of the specimen expansion cannot be completely removed; In heat treatment test found that treatment temperature 950℃℃is better than 750℃℃, 950℃℃can remove metallic aluminum in both of fly ash sample, and increase compressive strength of cement mortar; alkali treatment solves the expansion problem, but significantly lower both of fly ash sample’s compressive strength; Alkali-activated treatment also improve expansion problem, however, it do not improve the performance in high metallic aluminum content of fly ash, limited improvement in compressive strength of mortar, and even cause serious slow-setting in low concentration of alkali condition. The performance in low metallic aluminum content of fly ash can be improve significantly with alkali-activated treatment, the compressive strength under different alkali concentration, the strength can still be maintained at an acceptable level (higher than 40 MPa)When the fly ash content is as high as 50%. | en_US |