| Summary: | 碩士 === 國立中央大學 === 應用地質研究所 === 87 === A series of AAR tests was performed in this study to investigate different kinds of rocks and Hualienhsi aggregates in Taiwan , the testing results were further compared with local case studies.
It was found that matachert and mylonite from Central Range in eastern Taiwan, green porphyritic andesite, red porphyritic andesite and andesite from Coastal Range, and glass-rich andesite from Linshanpi in nortern Taiwan which belongs to Tatun volcanic system, revealed significant AAR features. Furthermore, green porphyritic andesite and red porphyritic andesite showed a typical ASR product which consists of Si, Na, Ca, K and Fe during reaction. Therefore, those materials can certainly be confirmed deleterious. On the other hand, basalt from Penghu； gneiss, mylonitic gneiss and marble from Central Range in eastern Taiwan, are safe to be used.
Among the deleterious aggregates, the andesitic aggregates caused the first cracking, in which green porphyritic andesite, red porphyritic andesite and andesite perform similar characteristics with larger cracks and local distribution. Glass-rich andesite caused uniform cracks with equal width. Mylonite, slate and metachert caused the latest cracking, the cracks were very thin and fragmentary distributed. In addition, the cracking of mortar bars are irrelevant with the expansion and content of gel.
The petrographic examination result showed that size and grain boundary of quartz in aggregates are the important mechanism of AAR, and it is easily to react with cement to cause damage when aggregates contain a lot of glass and quartz microcrystalline meterials. In general, the aggregates contain glass lead to more AAR expansion than contain quartz did.
The X-ray mapping result showed that the more Si and K ions contain in groundmass of andesites, the more AAR expansion, but the contents of Ca and Al ions are irrelevant to AAR.
As for Hualienhsi aggregates, the results from AAR tests showed a significant AAR potential, in which metachert, green porphyritic andesite and red porphyritic andesite are deleterious. Comparing the testing results with the results measures from local case studies, it is found that the concrete block which is made up of Hualienhsi aggregates show significant AAR characteristics. Therefore, we shall pay more attention to apply those aggregates in future construction work.
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