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Title |
Tensile Behavior of Hybrid Fiber Reinforced Cement Composite According to the Hooked Steel Fiber and Polyvinyl Alcohol Fiber Blending Ratio and Strain Rate
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Authors |
손민재(Min-Jae Son) ; 김규용(Gyu-Yong Kim) ; 이상규(Sang-Kyu Lee) ; 김홍섭(Hong-Seop Kim) ; 남정수(Jeong-Soo Nam) |
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DOI |
https://doi.org/10.11112/jksmi.2017.21.6.098 |
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Keywords |
변형속도 ; 섬유 혼합비 ; 인장거동 ; 동적증가계수 ; 시너지 효과 Strain rate ; Fiber blending ratio ; Tensile behavior ; Dynamic increase factor ; Synergistic response |
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Abstract |
In this study, the fiber blending ratio and strain rate effect on the tensile behavior of hybrid fiber reinforced cement composite was evaluated. Hooked steel fiber and polyvinyl alcohol fiber were used for reinforcing fiber. The fiber blending ratio of HSF+PVA were 1.5+0.5, 1.0+1.0 and 0.5+1.5vol.%. As a results, the tensile strength, strain capacity and fracture toughness of the hooked steel fiber reinforced cement composites were improved by the increase of the bond strength of the fiber and the matrix according to increase of strain rate. However, the tensile stress sharply decreased after the peak stress because of the decrease in the number of straightened pull-out fibers by micro cracks in the matrix around hooked steel fiber. On the other hand, PVA fiber showed cut-off fracture at strain rate 10-6/s with multiple cracks. However, at the strain rate 101/s, the multiple cracks and strain capacity were decreased because of the pull-out fracture of PVA fiber. The HSF1.5PVA0.5 shown the highest tensile strength because the PVA fiber suppressed the micro cracks in the matrix around the hooked steel fiber and improved the pull-out resistance of hooked steel fiber. Thus, DIF of strain capacity and fracture toughness of HSF1.5PVA were greatly improved. In addition, the synergistic response of fracture toughness was positive because the tensile stress was slowly decreased after the peak stress by improvement of the pull-out resistance of hooked steel fiber at strain rate 101/s
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