| dc.description.abstract | 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.
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