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Rehabilitation of corrosion damaged reinforced concrete beams with recycled nylon fiber reinforced sprayed polymer cement mortar
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| Title: | Rehabilitation of corrosion damaged reinforced concrete beams with recycled nylon fiber reinforced sprayed polymer cement mortar |
| Other Titles: | リサイクルナイロン繊維を混入したポリマーセメントモルタルによるコンクリート部材の補修効果 |
| Authors: | Orasutthikul, Shanya Browse this author |
| Issue Date: | 25-Sep-2017 |
| Publisher: | Hokkaido University |
| Abstract: | In recent decades, the world has been suffering from the dumping of wastes, especially plastics left in seas and oceans.Waste fishing nets account for some of these wastes: 640,000 tons of fishing nets are disposed of in the ocean annually.As the nets become totally entangled, separating them for disposal is impractical.These nets can be harmful to marine life, such as turtles, seals, and other marine mammals, which can become entangled and suffer injury or drowning. In addition, the marine food web could be disrupted.As abandoned nets and plastic garbage tend to gather at or near the surface of seas and oceans, they keep sunlight from reaching small creatures such as planktons and algae.Therefore, the animals that feed on these small creatures are also directly affected.Although the storage of such nets has not caused a serious safety hazard to date, it is important to find suitable recycling solutions.Therefore, it is important and urgent to find suitable way to recycle them. In the first stage, the author discussed the utilization of recycle waste fishing nets in fiber reinforced mortar.Experimental test results compared the mechanical properties of such mortar made with recycled (R-) nylon fiber to those of such mortar made with recycled polyethylene terephthalate (PET) and polyvinyl alcohol (PVA) short fibers.Two types of R- nylon fiber were investigated: straight fiber and fiber with a knot at each end.The straight R- nylon fibers were obtained by manually cutting waste fishing nets to the lengths of 20 mm, 30 mm, and 40 mm, and adding them to mortar at the volume ratios of 1.0%, 1.5%, and 2.0%.The 40-mm-long knotted fibers were added to mortar at the volume ratios of 0.5%, 0.75%, and 1.0%.The addition of R-nylon fibers improves first-crack strength more than that PVA fibers do.However, the compressive strength decreases with increase in fiber fraction, and decreases with increase in fiber aspect ratio. In the second stage, the author discussed whether R-nylon fiber can be used as an additive to sprayed polymer cement mortar (SPCM) to improve the structural performance of SPCM repairs.In this study, a novel R-nylon fiber SPCM was compared with two common types of SPCM: polyethylene (PE) fiber SPCM, and plain SPCM (without fiber).The experiments involved the removal of concrete to three depths, to represent three repair methods: removal to a depth of 10 mm, removal of all the cover concrete, and removal to a depth of 20 mm over the tensile reinforcements.Four-point bending tests were conducted on 38 reinforced concrete (RC) beams whose flexural behaviors (load carrying capacity, flexural stiffness and ductility) were investigated.SPCM containing R-nylon fiber was found to afford increases in load carrying capacity for the beams whose tensile reinforcement was reduced by 10% to 18% from corrosion, and it was found to provide higher ductility than the two common types of SPCM.The beams repaired with SPCM containing either of the fibers showed higher stiffness than those repaired with SPCM without fibers.It was found that, for the beams whose tensile reinforcement was reduced by 10% from corrosion, removing the whole concrete covering is suitable for improving flexural behavior and can be a better choice in terms of economic efficiency.Furthermore, for beams that have lost 10% to 18% of their tensile steel mass, it is recommended that concrete over the tensile reinforcements be removed to a depth of 20 mm and replaced by SPCM containing either type of fibers. |
| Conffering University: | 北海道大学 |
| Degree Report Number: | 甲第12905号 |
| Degree Level: | 博士 |
| Degree Discipline: | 工学 |
| Examination Committee Members: | (主査) 教授 横田 弘, 教授 上田 多門, 教授 杉山 隆文 |
| Degree Affiliation: | 工学院（北方圏環境政策工学専攻） |
| Type: | theses (doctoral) |
| URI: | http://hdl.handle.net/2115/70617 |
| Appears in Collections: | 課程博士 (Doctorate by way of Advanced Course) > 工学院(Graduate School of Engineering)
学位論文 (Theses) > 博士 （工学）
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