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|Keywords: ||韌性;混凝土;纖維;自癒合;應變硬化;ECC;Fiber;strain hardening;self healing|
|Issue Date: ||2014-10-15 14:22:42 (UTC+8)|
|Abstract: ||本研究以發展高韌性混凝土(Engineered Cementitious Composites，之後簡稱ECC)之本土化材料設計為出發點，討論水膠比之變化與製造流程的創新，探究其對ECC重要力學性質之影響，包含：拉力、壓力、撓曲性質、以及流變性質。成功利用本土化材料如水泥、飛灰、矽砂、以及強塑劑等，研發出兼具高流動性、高韌性、以及高強度之ECC材料，其抗壓應力超過50 MPa、抗拉應變量可達1-3%、且坍流度可達65公分。進一步，研發出五種高礦物摻料(Mineral Admixtures)的Green ECC配比，並探討其力學及流變性質之變化。結果顯示，提高飛灰量能增加Green ECC的韌性，但是會降低力學強度及工作性；相較於僅使用高量飛灰的配比，複合爐石粉於配比中，能改善流變性質，增進工作效能，提高早期強度，並保有優良的拉力應變及撓曲變形韌性。|
最後，探討ECC自癒合能力，以共振頻率(Resonant Frequency Test)、拉力試驗(Uniaxial Tensile Test)、以及SEM(Scanning Electron Microscope)來評估並觀察Green-ECC受到兩種不同程度破壞(Pre-Crack 0.5% and 1%)後，放置於三種不同環境下(包括水中、自然環境、以及乾燥環境)的自癒合程度。研究發現，所有配比在水中以及自然環境中皆有自癒合的行為發生。其中，共振頻率恢復程度方面，以高飛灰量的配比表現較好。而複合爐石粉的配比，其拉應力及勁度恢復程度較佳。
;The objectives of this research are to develop Engineered Cementitious Composites (ECC) using locally available materials, and to evaluate the self-healing behavior of ECC. The study starts by designing the mixture proportions using locally available materials in Taiwan. The effects of water binder ratio and mixing method on the mechanical and rheological properties (including tensile properties, compressive properties, and flexural properties) of the developed ECC are studied. The study successfully used the locally available materials such as cement, fly ash, silica sand, and superplasticizer etc., to develop the ECC with high flowability, ductility and strength. In particular, the compressive stress is over 50 MPa, tensile strain is up to 1-3%, and the slump flow can reach to 65 cm. Furthermore, five different mixture designs of Green-ECC with high volumes of mineral admixtures are developed. Experiments are carried out to evaluate their mechanical and rheological properties. The experimental results show that while Green-ECC with high volume of fly ash can enhance the tensile strain capacity, the compressive stress and workability are decreased. Compared to using only high volume of fly ash, the mixtures containing fly ash and slag can enhance the workability, early strength while maintaining excellent tensile strain capacity and flexural deflection capacity.
Investigations are carried out on self-healing capacities of ECC specimens with two different degrees of pre-crack (0.5% and 1%) and three different storage environments (including water, natural environment, as well as dry conditions). To quantify self-healing behavior of Green-ECC, the resonant frequency test and uniaxial tensile test (UTT) are conducted. In addition, Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS) are used to observe and analyze the self-healing products. The test results reveal that all specimens of Green-ECC show self-healing behavior under water and natural environment. The specimens of high volume of fly ash exhibit the best self-healing performance in terms of the recovery ratio of the resonance frequency. The mixtures incorporating fly ash and slag show the best recovery with respects to tensile stress and stiffness.
|Appears in Collections:||[土木工程研究所] 博碩士論文|
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