煤灰製作控制性低強度材料之研究

台灣混凝土學會 2009 年混凝土工程研討會
TCI 2009 Concrete Technology Conference
Paper No. N-02

煤灰製作控制性低強度材料之研究
The Study of Using Fly Ash and Bottom Ash in Controlled Low Strength Concrete
郭麗雯1、鄭瑞濱2、邱暉仁3、許讚全1、賴正義4
1台灣電力公司綜合研究所化學資深研究專員
2財團法人臺灣營建研究院所長
3財團法人臺灣營建研究院助理工程師
4國立台灣科技大學營建工程系博士後研究員

摘要

台電公司目前所使用之控制性低強度材料係依據台北市政府的材料規範，其配比材料主要包括水泥、爐灰，以及粗、細骨材。近年來，台電已陸續改採淡水替代海水做為燃煤電廠出灰系統冷卻輸送之用，為提高燃煤電廠煤灰利用率，本研究採用台中火力電廠煤灰，於實驗室拌製多組配比之含煤灰控制性低強度材料，探討其流動性、初凝時間與抗壓強度等工程性質，另於施工現場採用四組配比，進行示範工程。
本研究試驗結果顯示，在坍度大於40公分下，以90%之底灰與10%之飛灰完全取代細骨材可以產製一般型控制性低強度材料，其初凝時間小於6小時，12小時抗壓強度約為5 Kg/cm3，28天強度不高於70 Kg/cm3。另在早強型控制性低強度材料的產製中，以底灰取代20%細骨材、飛灰取代10%細骨材及20%水泥，並配合5%早強劑，其初凝時間小於5小時，12小時強度高於7 Kg/cm3，28天強度約70 Kg/cm3。另在現場示範工程中，以50%底灰取代開挖之黏土，對工作性與攪拌均勻性有很顯著的改善。


關鍵字：底灰、飛灰、控制性低強度材料、初凝時間、抗壓強度

ABSTRACT

Currently, controlled low strength material used by Taiwan Power Company is made following the material specification of Taipei city government and its main ingredients are cement, slag, coarse and fine aggregates. Recently, freshwater has been gradually adopted to replace seawater in ash delivering system of coal-fired power plants at Taiwan Power Company. To enhance coal-fired ash utilization, the ash from Tai-Chung power plant is used in this study to fabricate several mixes of controlled low strength material at laboratory to study their engineering properties such as flowability, initial setting time and compressive strength. Then, four mixes are adopted for site demonstration construction.
The test results show that, under slump greater than 40 cm, ordinary controlled low strength material can be fabricated by using 90% bottom ash and 10% fly ash to completely substitute fine aggregate, by weight. The relevant initial setting time is less than 6 hours, and 12-hour and 28-day compressive strengths are respectively around 5 Kg/cm3 and within the range of 65-70 Kg/cm3. Moreover, early-strength controlled low strength material can be fabricated by using bottom ash to substitute 20% fine aggregate, fly ash to substitute 10% fine aggregate as well as 20% cement, and using 5% accelerator. The relevant initial setting time is less than 5 hours, and 12-hour and 28-day compressive strengths are respectively higher than 7 Kg/cm3 and around 70 Kg/cm3. As to site demonstration construction, the replacement of excavated clay by 50% bottom ash can significantly improve workability and mixing uniformity.
keywords: controlled low strength material, fly ash, bottom ash, initial setting time, compressive strength