| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 104 === High strength materials have been widely used because using high strength concrete and reinforcement can further reduce the member section, which lights the weight of the elements and increases the available space of buildings, and save materials. To solve the brittleness of high strength concrete, the addition of the steel fibers can provide more confinement and shear capacity to enhance the ductility and toughness. It also prevents the early cover spalling and solves the congestion of the transverse reinforcements in the plastic hinge region of buildings.
Although the addition of the steel fibers provides good benefit on mechanical behavior of high strength concrete, Taiwan is an island surrounded by sea with the subtropical climate, made the structures easily deteriorated by salt damage. Worried about the chloride ion may penetrate into the concrete from the interfacial transition zone (ITZ) between the steel fibers and cement paste, and therefore reduce the durability of the structures. The other hesitation is the steel fibers may easily corrode so that the steel fibers lose its advantage, inducing the steel-fiber concrete structures become weaker.
This study investigates the addition of the steel fibers influencing the durability of the high strength concrete. The experiment divides into two parts. One is using the ponding test to discuss the ITZ of the materials. According to the result, the diffusion coefficient doesn’t change between the content of steel fibers. The other is using salt spray test to simulate the structures exposing outside several years. Finally, doing mechanical experiments, such as compressive test and flexural test to evaluate the mechanical behavior after the deterioration process. According the result of the mechanical test, the strength doesn’t worsen after the deterioration by the salt spray test.
In summary, the addition of the steel fibers doesn’t reduce the durability of high strength concrete.
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