飛灰水泥乾拌料之蒸汽水化現象及其混凝土抗壓強度之測試

Abstract

依據行政院國家科學委員會81年度「蒸汽催行水泥材料的水化機理及物理 性質之研究」報告，乾拌╱蒸汽工法將蒸汽熱能轉移至水泥顆粒，提高水 泥內能，縮短超越能障時間，並迫使水份進入水泥顆粒內部，提高水化程 度，在短時間內製造高強度之混凝土。台灣電力公司火力發電的副產物─ 飛灰，每年的產量相當多，而飛灰係波索蘭材料，惟反應速率較緩慢。本 研究利用乾拌╱蒸汽工法的特性，激發飛灰加速反應，以製造混凝土。試 驗結果證實，此工法鑄造薄尺寸的試體，能增加飛灰取代普通水泥之比例 、縮短工期並提高試體強度等優點。例如10cm立體之混凝土試體，飛灰取 代40%的水泥，以200℃□溫進行13.5小時後，其抗壓強度達641kgf/cm2。 本研究亦提出蒸汽催行改善方法，以備將來發展實足尺寸結構構件之參考 。以熱重量儀（Thermogravimetry）分析乾拌╱蒸汽水泥漿體，發現漿體 燒失分解溫度比濕拌者高，由此可推，其抗火性能可能優於濕拌者。飛灰 水泥漿體之波索蘭反應產物，在試燒至溫度 105∼440℃時，其分解現象 特別顯明，容易測定飛灰之波索蘭反應程度。 In 1991 the National Science Council of Republic of China funded a research program, entitled"Hydration Mechanisms and Physical Properties of Cementitious Materials Hardened through The Dry-mix/Steam-Injection Process". The test results indicate that the transfer of heat energy from steam to cement particles at the moment of contact triggers a repid hydration reaction when the activation energy reaches the energy barrier. Concrete thus made developed high strength in relatively short period of time, about one day. It was envisioned that the Pozzolanic materials such as fly ash may have similar behavior as that of the portland cement under the effect of steam. Fly Ash, a by- product of power plants, requires an adequate study for reuses. It generally reacts slowly in Wet process, may however, react rapidly in a pressurized steam condition. The objective of the program is to verify the concept of hydrating the dry fly ash cement by steam. The test results reveal that fly ash concrete made through the dry-mix/steam injection process substantially shortens the hydration time and increases the concrete strength as well. For example, it developed 641 kgf/cm2 strength with a 40% fly ash substitution under a 13.5 hour exposure to 200℃ steam. This report suggests ways to optimize the diffusion mechanisom during the steaming period. The hardened paste of steamed fly ash concrete was examined by the ignition loss process. The result shows that the decomposition phenomenon is quite clear in the temperature range of 105 to 440℃.