氧化鈣含量對水中自充填混凝土坍損與工程性質之影響

Abstract

卜作嵐材料皆含有氧化鈣但由於來源、製作過程和成分種類等的不同其氧化鈣的含量有所不同。本研究以探討混凝土中氧化鈣含量的多寡，對水中自充填混凝土在坍流度損失及工程性質上的影響為試驗目標，使用不同比例的氧化鈣來取代(5% 10% 15% 20% 25% 30%)卜作嵐材料(飛灰)除了製作出具有自充填、水中不析離特性之水中自充填混凝土，並每間隔15分鐘量測其坍流度值一直量測到90分鐘，比較各種不同氧化鈣含量坍流度的損失。在混凝土硬固後放置相對濕度(RH80%、RH100%)的環境中，測試其力學性質、體積穩定性及耐久性，以確保混凝土之品質並比較取代量不同之差異，比較內容包括抗壓及劈裂強度(力學性質)、乾燥收縮(體積穩定)、電阻值(耐久性)及重量損失。由試驗結果得知，添加氧化鈣的含量多寡其水中不分散能力(通過L型流度測試之pH值與濁度值)能保持不添加之品質但流動的長度方面隨著添加量增加有略小一些，而坍流度損失的方面亦會隨著氧化鈣含量的增加而變大，直到經過60-75分鐘後變化漸相近。由此可以得知水中自充填混凝土中氧化鈣的含量確實會對其坍流度損失造成影響並隨著含量的增加而變大。

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.