| Summary: | 碩士 === 國立交通大學 === 土木工程系所 === 104 === Pozzolans materials contain CaO, which varies in content as a result of different sources, producing processes and varied types of composition. This research is aim to discuss the impacts of different CaO content on the engineering properties and the slump-flow loss of underwater self-compacting concrete, utilizing various proportions(5% 10% 15% 20% 25% 30%) of CaO in substitution for Pozzolans materials(fly ash) to make underwater self-compacting concrete with properties of underwater self-compacting and underwater anti-segregation, measuring the slump-flow value every 15 minutes until reaching 90 minutes to compare the slump-flow loss in different content of CaO. The specimens are kept in different related humidity(RH80% RH100%) after the concrete harden; the mechanical properties, volume stability and durability are tested in order to assure the quality of the concrete as well as to compare diversities among different proportions of substitution, including pressure resistance, cleavage strength(mechanical properties), shrinkage(volumetric stability), resistance(durability) and weight loss. According to the test result, regardless of the amount of CaO added,the underwater anti-segregation capacity(pH value and turbidity which have passed the L-test) is able to maintain the quality as without adding any CaO. Nevertheless, the flowing length slightly decreases as the addition level of CaO is increased, yet the scale of slump-flow loss raises as the content of CaO is increased until the variations gradually close up after 60-75 minutes. Thus, it can be seen that varied proportions of CaO content in underwater self-compacting concrete indeed has effects on the slump-flow loss which grows to larger scale as the content of CaO increases.
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